Repair and Diagnosis of Problems with Your Imperial's Voltage Regulator

Imperial Home Page -> Repair -> Electrical System -> Charging System -> Voltage Regulator

How to change your voltage regulator (1967 model shown), contributed by Leslie.

Tip from Mikey and Bruno:

It is not only possible but it is very, very easy to change an Imperial, or any other pre electronic voltage regulator Chrysler product over to electronic regulation.  There are a couple of ways.........the first one, and possibly the easiest is to get a VR1001 regulator at NAPA or your favorite parts place.   It replaces the old points style unit but uses the same wire connections as the points unit.  The other option is to install a later Chrysler alternator ( known as the dual field, because both field terminals are positive as opposed to early stuff where one was grounded ) and later style regulator.  You have to add 1 piece of wire and also get the harness plug for the regulator, but its just as easy and effective.  The end result is that you still get the 14.2-14.5 volts charge voltage and whatever amps that your system is demanding at the moment, but it greatly reduces voltage spikes and the needle on the ammeter seems much more smooth in its motion on my 62.  One thing for sure, if you have the Chrysler electronic ignition, they recommend it.    

From Bruno:

The newer style regulator is called an Isolated field not a dual field. One field terminal goes to the ignition switch, and the other connects to the green lead on the regulator. The regulator controls the voltage potential across the field and thereby controlling charging voltage and current.

Conversion from mechanical to electric - by Frank:

The difference between the electronic regulator and the mechanical one is the electronic regulator is in  the field coil's GROUND circuit and the mechanical regulator is in the field coil's HOT circuit. (The electronic regulator was moved to the ground circuit since a short would not cause the regulator to self-destruct.

You need:
1) Electronic regulator (all are the same)

2) New or rebuilt alternator - or convert brushes to new style where BOTH brush sets are insulated from  the alternator frame. (Use an alternator from the 70's or later, but NOT one from the FWD cars since some had different mounts. Don't use the 45 amp alternator, it does not
have enough power, and the 100 
amp requires a different mounting bracket.)

3) length of wire. 18Ga or greater (lower number = high (thicker) gauge)

4) Electronic regulator connector. (Salvage from junk yard.)

To convert from the old mechanical to the newer electronic regulator you need to:

1) Remove the mechanical regulator from the car and mount an electronic regulator. Make certain that the regulator has a GOOD GROUND connection.

2) The field coil is grounded inside the alternator on the mechanically regulated alternators. This must be changed. I think that it is possible to use the newer style brushes that insulate both field wires from the alternator housing. Since my alternator's bearing were shot, I replaced the '68's alternator with a later model one.

3) Connect the one field wire to one of the field terminals. The new alternator has two field terminals, as opposed to the one field terminal on the old alternator.

4) There are two wires at the mechanical regulator. One is from the ignition circuit and is hot when the key is "on". The other connects the regulator to the alternator. Connect these two wires together with a new wire (so that you have a connection of 3 wires.) The new wire goes to the DARK BLUE wire on the salvaged regulator connector.

5) Run a new wire from the second field terminal on the alternator to the DARK GREEN wire on the regulator connector.

6) TEST. Ignition off. Using a meter check that there is no connection between ground and either terminal of the regulator's connector. Check that there is also no connection between ground and either field terminal on the alternator. Check that there is zero ohms between the body and the regulator's case.

7) Test. Ignition on. DO NOT START ENGINE. Remove new wire (that connects alternator to regulator's GREEN wire.) Using a meter check that there is +12V on the regulator's center terminal ONLY. Check that there is +12V on the two terminals of the alternator. Re-connect
alternator field wire removed at the beginning of this test. There now should be +12V on both regulator terminals. Ignition switch off.

8) Connect regulator connector to regulator.

9) Connect voltmeter to the battery terminals. A fully charged battery should be 13.2 volts. (2.2 volts/ cell of a lead-acid battery X 6 cells.) Voltage maybe a bit less depending on the condition of your battery. Start engine and run at fast idle (1200 RPM or so). Voltage should now be 13.8 to 14.5 volts. 

Regulation should be stable, with no large voltage fluctuations. If there is a problem, recheck your connections and the regulator's ground. Remove voltmeter from battery.

10) Finished!

Question from Philippe (1957):

I have known for several weeks that the voltage is a little high in my Imperial: I checked the voltage at the battery posts with the engine running at idle and it's between 15.5 and 16 V.

First question: what should be the correct voltage?  The FSM says that: - the "voltage setting" of the regulator must be between 14.3 and 14.9 at 70 F, a little lower if t increase. - The regulator cut-out relay must close between 13 and 13.75 V. So what is the measurement I should be reading on the battery posts?

Second question: is the voltage setting adjustment (bending lower hanger of the voltage regulator spring up) an easy adjustment and is this setting the first thing I'll have to make?  I have a voltmeter, some knowledge about electricity but no special tools or equipment like "carbon pile rheostat" or 50 Ampermeter ..


From Dick:

The voltage at the regulator is the important item. If the regulator is set to the correct voltage, your battery will also be at the right voltage. It is difficult to tell you what you should measure at the battery post, because it depends on too many variables. To list a few, the battery condition and materials used in construction both contribute to its internal resistance, plus the charging rate at the instant you make the measurement all affect the battery voltage.

If your voltage regulator is allowing the battery to charge up to over 15 volts at idle, when the car has been running long enough to be certain the battery has recovered from the starting drain, then the voltage regulator is definitely in trouble, but if you measure this voltage shortly after starting the car, especially on a cold day, and with a possibly less than perfect meter, it could be normal.

To get around all this variation, measure the voltage at the regulator "A" terminal directly, with the engine idling fast enough that the battery is charging, and after the battery has recovered from the starting drain (by this I mean that the charging rate has dropped back toward the center of the gauge, just as if you had driven 10 miles in daytime use). If the voltage is within the specified limits (14.3 to 14.9), then you can relax. If it is higher, you probably should replace the regulator, but if you are brave, you can try bending the return spring hanger. My experience is that this usually leads to more troubles. As I'm sure your manual tells you, you need to measure this voltage at particular conditions of charging rate, and the cover must be in place as it affects the magnetic circuit of the regulator. As you point out, you are not going to have the proper devices to measure this accurately, so I'd advise just replacing the regulator.

Before you go to all this trouble, verify that your voltmeter is accurate. If you take it to a radio repair shop, they should be able to check it for you against a known standard. If you measure the battery voltage on a modern car, when that car has not been run for 12 hours or so and there are no drains on the battery, your meter should read around 12.8 volts. If it does, probably your meter is close enough to trust.

From Adam:

I had a "flashing" (dancing alt. gauge - flashing lights) situation on my '64 and with Dick's advice went to NAPA and replaced my mechanical regulator with an electronic one. Its about $50 and works great. The electronic replacement mounts on the inner LF fender just like the OEM unit, even lines up with the original mounting holes. At first the "youthful" counter person at NAPA didn't believe there was an electronic replacement, but then I gave him the part # I got from Dick - he was surprised.  Of course, this is a car with an alternator...

Follow-up from Philippe:

About my battery, it is new and fully charged.   The generator (GGA 6001 : 40 A) has the correct regulator (VAT 6201 : 40 A).  What could happen if I replace the regulator with some spare I've but which are 30 A (VRX 6201 or 2095341, the last seems in very good apparent conditions)?  Damages to my regulator or generator?

Where could I find a new 40 A regulator which replaces VAT 6201 ? NAPA ? Too bad that I couldn't put an electronic regulator ...

Reply from Dick:

Don't change the regulator until you verify that the old one is bad. Have you verified the accuracy of your volt meter?

Putting on a 30 Ampere regulator won't hurt anything, but it will take longer to recharge your battery after a drain, and may not keep up with your cars needs for nighttime or heavy traffic driving. Do you have traffic in France? I'd think you could just mow down the 203s and CV-2s, and not even slow down for traffic, so your battery would stay up fine with a 30 AMP regulator. If, on the other hand, you have to deal with slow driving in winter months will heater, headlights, radio etc. on, you'd better replace it with a 40 Amp regulator.

Question from Bryan (1959):

I have several collectible cars and have been an avid proponent of upgrading to electronic ignition; enough so that I did it to my 59 Imperial coupe.  Initially, I was somewhat wary, given the fact that the 59 has a generator and that the instructions called for an upgrade to an electronic voltage regulator.  However, a friend who owned an auto repair shop had done the same with his 59 Desoto with no problem.  Anyway, it has been about 8 years.  It runs great, BUT, I had ignition problems last year and ended-up replacing the distributor.  I have also noticed that any battery installed begins to leak.  Do I just have a bad voltage regulator?  Or is the electronic ignition causing the regulator to fail.  Again, this is not the electronic voltage regulator called for by Mopar, but rather the original type regulator.  I do remember repeatedly "frying" the points with the old conventional distributor.  Evidently, this also "fried" the pick-up coil and reluctor in the electronic distributor.

Reply from Brad:

I'd vote for voltage regulator.  The distributor/coil are "slaves" to the voltage regulator as is the battery.  The surest way to boil a battery is over-charging.  Test the voltage regulator.  It should calm down to +13V SOON after starting.  The voltage regulator (internal w/ alternator) in my wife's Bonneville fried the battery and it only tested to +15V (after a lengthy stabilization from near +20).  I'd check that first.

Question from Greg (1961):

The battery indicator on my '61 is on the discharging side constantly. It's worse if the air conditioner is on. Do I try replacing the voltage regulator first, or go ahead with new alternator AND voltage regulator?  


From Mac:

Some of the auto parts stores will check your charging system for free, I know that Checker will and Auto Zone. They can check your Alternator and Voltage Regulator as well as your battery, and that would give you something to go on before you spend money on parts you may not need.

From Mark:

You might also check Sears Auto Centers.

From Bob:

I'm not a mechanical ace by any stretch, but my first step would be to find a car book with a section "Troubleshooting the Charging System" (or maybe it's on the Internet) and look for some step-by-step advice. Or take it to a shop that can perform some basic tests. Should save time & money rather than replacing parts without knowing the cause(s) of the problem.

Question from Carl (1965):

I had a problem with my car charging, so I changed the regulator and it didn't correct the situation. In fact, the car is now discharging and never moves to the right portion of the gauge. Any suggestions?


From Jeff:

One time I was jumping my 1965 Brand T with my 1965 Brand L-C and reversed the polarity. Didn't blow up the battery, but the L_C was discharging. Replacement of voltage regulator was no remedy, it turns out I had damaged a diode in the alternator. I would suggest having the alternator checked- if it's not outputting, there won't be enough to regulate.

From Greg:

I had trouble with my 66 Imp horn too. The problem turned out to be the connection at the steering column isolator. The horn ring gets its ground through the steering column, that column is jumpered across the rubber isolator where it makes contact to the frame through the steering gear box. You might check it out the isolator is on the engine side of the firewall.

From Elijah:

I had some difficulty last year in getting the horn working on my '71 Imperial. In the case of my car, the fault was in the steering column -- there's a small metal spring inside the column (spring is inside the column beneath the steering wheel, and turns with the wheel -- touches a metal plate that is stationary in the column) that acts as a contact when the horn ring is depressed, and this spring had collapsed. I replaced it with a spring from a ballpoint pen, and the horn works perfectly now.

From Jay:

The horn relay on the '66 is either near the battery or just forward of the radiator wall on the driver's side forward of the battery. Rectangular and about 2" long and 1" wide and has three prongs coming out of it into two connectors to the wiring harness. Should be the same on your '65. If in doubt, trace the wires coming directly off the horns back down the wiring harness and the first component you will come to will be the horn relay.

Question from Jay (1966):

I finally got around to checking into the voltage regulator for my '66 Crown.  The voltage regulator sits on the left wall of the engine compartment, right next to the starter relay. The '66 shop manual shows the two different kinds used and what they look like. I checked the voltages during engine off and fast idle conditions. The numbers were 12 1/2 and 15 respectively. Just to be safe, I decided to replace the 33 year old unit.  Pep Boys had one in stock for only $12.99. NAPA wanted $34.00!  The new voltage regulator looked like an exact match for the one pictured in the shop manual right down to the resistive coils on the back side. The old voltage regulator did not have these coils.  Perhaps the old voltage regulator is not the original (incorrect replacement by a previous owner?)

Reply from Dick:

The 15 volts is not outrageously high, but whether or not it would damage a battery depends on how long it stays that high, and what condition your battery was in when you made the measurement.  I'd also like to know the under-hood temp.  If the battery was warm, and the voltage stays that high (I assume you are measuring it right at the battery terminals), then I understand why your battery blew up or nearly did.  The 12.5  volts with the engine off sounds like your battery was already fully charged, so the regulator should not have been pouring that much current into it, unless the battery had to crank a long time to start the car, and the temp was quite low.  I assure you the regulators both have the resistors, they just must be hidden inside on the one (I have never seen this, usually the designers want the resistors exposed to air currents,  that's why they are on the outside of the regulator).  It is true that Pep Boys sell their merchandise much cheaper than NAPA.   NAPA does have a low cost line also, called "Silverline", but not all stores stock it.  Be warned, though, you get what you pay for.   The NAPA premium line is made by Echlin, and is equal or at least very close to OEM quality.  Probably something like a regulator is going to work as well even if it is cheaply made, as long as it is OK out of the box.  It won't have the durability that the original did, though.  Just keep an eye on that Ammeter for a while, until you build up confidence in it.   The car should charge the battery at a high rate of charge after each start for about 10 times as long as you had to  crank it to start the engine - in other words, if you crank for 5 seconds to start it up, it should show a Max charge for about 1 minute, then drop back almost to zero charge in incremental steps.

Question from Spence (1967):

My '67 has the old, pulsating light symptoms.  Am I correct in assuming that I can replace the old regulator with an electronic one with no other alterations? 


From Frank:

I replaced mine without changing anything else.

From Ken:

Last fall I spent a lot to replace everything that could possibly be causing the "pulsating lights", alternator, regulator, etc.,etc.. When all of this was done and I still had the problem, I was in the process of cleaning and checking EVERY electrical connection on the car when the subject of the electronic voltage regulator came up on IML. I was skeptical, since my mechanical one was now brand new, and I figured that if it really was the cause of the problem, replacing a 35 year old regulator would have had <some> effect. But I bought the electronic one anyway, since it was relatively cheap (~$20.00), and I was amazed. 

Question from Mac (1968):

I have a 68 Crown that seems to have this problem it discharges when at an idle. The meter shows it charging when I take off but when I'm at a stop light or at an Idle it shows a discharge. I replaced the alternator after having it tested. They tested it while it was still on the car. It would charge above 2000 RPM but not at an idle, so I put a new alternator on it. It starts okay but if I have to do a lot of stop and go it will discharge more that it charges and I have to get it jump started. I have thought about replacing the voltage regulator, my local parts house has one in stock and it's only about $10. Any ideas...

Reply from Dick:

Unless your idle is really slow, it should charge at idle. I suspect the voltage regulator, if the wiring is all clean and tight on the alternator and the regulator. By the way, verify that when everything is off in the car (like when you disconnect one battery cable) that the ammeter really returns to dead zero. If not, you need to adjust your thinking to realize the true zero point, maybe you are charging at idle, but the gauge is off a tad.

Question from T.D. (1969):

I am need of info or advice on troubleshooting a recurring electrical anomaly. I replaced the voltage regulator about a month ago, and it seemed to resolve my turn signal indicator light staying on steady, and the volt meter moving back and forth. But, the problem seems to have returned and I can't for the life of me find this elusive poltergeist. I have spent much time @ Advanced Auto Parts, really helpful people and they have about 90 to 95 % of anything I need, except experience with older vehicles. I would really like to find a solution to this situation before Carlisle next month. I am considering selling this BEAUTY of a vehicle, mainly because it doesn't fit in my garage and my wife won't let me build a new garage for it. 

Reply from Roy:

At some point Ma Mopar went to electronic regulators and if your car already has an electronic regulator you have a more serious problem. However, after the ATC on my 67 was fully functional with a refrigerant charge, I went through three mechanical regulators because the points would get fried. There were no symptoms other than no charge and once when the regulator was stuck to cause the alternator to put out full charge (I thought I had halogen headlights!). I was unable to find anything wrong and chalked it up to the extra load put on the charging system by the AC compressor clutch was a bit too much for the 60 amp alternator to handle. I decided to try a Mopar electronic regulator since it didn't have mechanical points that could get fried and sure enough it has held up nicely.

Question from Ed (1981-1983):

I just changed the voltage regulator on my 81, and I am concerned that it is not properly calibrated.  Voltage should read between 13.8 and 14.8 at 70 degrees. When I first started the motor with the new regulator installed, ambient temp. about 80 degrees, it was reading about 15.2 volts. After a few minutes, it had come down to about 14.7-14.8 volts, right at the top of the acceptable range. I figured that perhaps the battery was slightly discharged when first started and so the v. r. was commanding more volts to charge it. So I loaded the system up at idle, with headlights, full fan speed, and turn signals/cornering lamps on, and the voltage dropped to about 12.3, as expected. Then when I turned the accessories off, the voltage returned to about 15.2 volts again, presumably to recharge the now slightly weakened battery. Eventually it dropped to about 14.8 volts again. Does this seem ok?

Reply from Dick:

I think you have analyzed the situation correctly, your regulator seems to be working just fine, and it is probably set near the top of the optimum range, but I doubt this is going to hurt anything. Enjoy the bright lights! Especially if you have the original Halogens, you'll be right up there with modern cars, or better, in seeing where you're going. You have probably already checked this, but if not, make sure the regulator mounting tabs are clean and making good contact to the body, and that the large wire from the alternator to the battery is in very good condition and making good contact. Resistance in this wire will make the alternator run toward the high side as to voltage. Are you measuring the 15.2 volts at the battery or at the alternator? If the former, your battery has somewhat high internal resistance, which means it may not be in the best of conditions. Does the starter crank with great alacrity, or is it a little sluggish? If you are measuring this voltage at the alternator directly, drop in the wiring accounts for some of the higher voltage (due to the resistance).

Question (1981-1983):

When driving from Minneapolis to Tulsa, the voltage light illuminated on my 1982 FS. After rebuilding the alternator, the problem went away. Until last week.  After about twenty minutes of driving, the light came on (on  2 consecutive short trips). It got a new voltage regulator last year.  What is wrong now? Could the diode in the instrument panel be bad? I  have a spare alternator I may install for troubleshooting. Any ideas?

Reply from Frank:

The light illuminates when system voltage (measured by the dash computer) falls below 11.2 volts. First, check voltage at the battery with the engine running. Run at 1250 RPM. Voltage should be as below: 

Temp near regulator       Voltage range 

-20F                                14.9 - 15.9 

80F                                 13.9 - 14.6

140F                               13.3 - 13.9 

above 140F                     less than 13.60

My 83 Imperial, charges at about 13.4 when the engine compartment was hot. 

If voltage is low: ALL CHECKS are IGNITION ON and ENGINE NOT RUNNING, unless otherwise noted. 

1) Check regulator has a good ground. (grounded by mounting screws.) 

2) Check that there is full battery voltage available between ground and the DARK BLUE wire from the regulator's connector.

3) Check that there is battery voltage at the DARK BLUE wire on the alternator.

4) With the engine running check the voltage @ the battery while QUICKLY connecting the DARK GREEN wire from the regulator's connector. 

5) Check that there is near zero resistance from the battery's POSITIVE connector to the output stud on the alternator. 


1) Bad regulator ground. Clean ground connection around mounting screws and re-test. 

2) Lower voltage at regulator than at battery. Check for faulty wiring. 

3) Lower (or no) voltage at alternator blue wire - wiring fault 

4) Voltage does not rise to 14+ volts, alternator / wiring fault. Connect DARK GREEN ALTERNATOR wire briefly to ground. If voltage at the battery does not rise to 14+ volts, alternator failure. If it does charge, wiring fault. 

5) Resistance in this wire is a wiring fault. 

If the voltage is not low at the battery, check the wiring to the dash cluster. Ignition voltage is on pin 3 (Dark Blue wire). Battery voltage is on pin 1 (Pink wire). Ground is on pin 2 (Black w/ Light Green tracer). Check voltages and ground.

Question from John:

Does anybody know of what electronic voltage regulator would replace the mechanical unit that is originally on these cars? Is this electronic  regulator available from Chrysler only or can normal parts stores have  them?  I also noticed that my charging gauge fluctuates but only under electrical loads, as in headlights being on. 


From Jeff:

I think Napa has an electronic replacement Voltage regulator. They did for my 68 Chrysler and I think it is the same on the 67 Imp.

From Elijah:

NAPA should have the correct voltage regulator. I'm not sure if you'll need to make any modifications to the wiring to make it work -- Dick, or somebody else, any ideas on that one? If you do buy the electronic voltage regulator, I recommend asking for a "heavy duty" one. NAPA carries a light duty version, but I found that the loads carried by my '71 tended to be too much for the light duty version. And what NAPA calls the heavy duty version is much closer to the original capacity of the voltage regulator.

Follow-up from Dick:

Nope, should interchange with no other adjustments, although I personally have never had a problem with the original type either, on my 67 or 68's.

From Bill:

Any parts store will have them.  Most Mopar products switched to electronic ignition in 1971, so look after this year to get one.  They are very easy to install... in less than an hour! Instructions included!

From Ron:

The electronic regulator that Chrysler offers is the best available and priced well below the chain stores. It's featured in their Performance catalog. It is blue in color, (good way to identify) and fits right in the old mounting spot. It was developed to regulate a constant/minimum of 13.4 vt's and eliminate the needle rattle. I paid approx. $16.00 @ Pitre Chrysler in Phoenix and felt that was a great deal against buying the same old design @ $8.00.

Question from Tony:

I noticed that my headlights have an odd pulsating low-bright pattern, around twice per second. If the car is at rest, there is no pulsing, but at acceleration the effect is most noticeable. I'm sure it looks odd to the folks ahead of me on the freeway at night, throbbing in their rear-view mirror.  Any clues on what would cause this and how I would be able to stop it?  


From George:

1. check the voltage regulator at fast idle (or higher), it may be "cutting out"...but then your charging gauge would be doing the dance as well.   

2. Likewise with the main ground strap. 

3. Alternator output (with the engine 'turning' above 1200-1500RPM), versus what's coming out of the regulator. 

4. The circuit breaker for the lights (although it doesn't sound like they are going off all the way). #2 would be the likely culprit (at idle the generator doesn't put out more than the battery, which is why they don't flicker then....but they will {or should} dim) The lights suck a lot of power, so for them to dim off and on would suggest the charging system is having an on/off event, the voltage regulator has a point setup to tell it when to open and close (the bright=charge, dim=battery). OR your alternator/battery output is going to something else. Something else (take your pick as long as it is electrical) could be borrowing the juice, or worse shorting to ground. If the lights do their thing while parked (and the engine running above idle) pulling a few fuses one at a time might be a wise hunt.  Feel that light switch, see if it is warm (the dash rheostat will be a little warm after a while, be it shouldn't be too hot to touch), likewise with the wires under that dash!

From Jay:

The alternator could be attempting to charge a full battery and tripping the regulator. One solution is to just put an electronic voltage regulator in the line.

From Elijah:

Try a new voltage regulator. This fix solved a similar problem for me a few years back.

From Frank:

Chryslers, earlier than '69 (I think) use mechanical voltage regulators. I'll bet that the relays in your unit are not calibrated or working correctly. I only vaguely remember what they looked like internally, so I can't really help too much. I replaced the mechanical regulator on my '68 with the better electronic one. It requires a slight re-wiring of the charging circuit, but results in better voltage control. Put a voltmeter in the car and watch the value. Should stay between 13.8 and 14.5.


Is there anything I can do to avoid the regulator getting stupid, other than pray each time before I start the car? Right now, I'm scared to death to drive this thing!


From Marcus:

I have a standard stock regulator on my '67 I also had the alternator rebuilt to its original specs. Periodically I take the cover off the regulator and clean it but good w/ contact cleaner, it looks new on the inside. I also replaced all the rubber mounting bushings. I recently installed a Mopar electronic distributor w/ module and have had no problems with any of it.

From Carmine:

The tech support people at Mopar Performance do not condone this! They recommend switching to the later regulator with the electronic ignition conversion.

The "modern" transistorized electronic ignition isn't tolerant of the occasional voltage spikes associated with mechanical regulators. There is a Mopar solid-state voltage regulator made for this conversion. Under $20.

Question from Gary (voltage limiter):

I got a cluster voltage regulator for my gauges... My car is a 66 Imperial coupe, and my question is. Where is this thing located, and how do I get to it..


From David:

I had to take mine out in the 66 it started to smoke. Its actually an amp meter and it was a pain in the ass to get out. I had to drop the steering wheel remove the chrome piece of the dash then the plastic piece then get up underneath, behind the amp meter and find the connections. There 2 large wires red and black in my case I just cut them, masked them off and put everything back together. The amp meter is tied into the sentry signal and the ignition so watch what you do.

From Gen:

According to the 1966 Chrysler/Imperial (factory) Service Manual, Section "Instruments-Indicators--Electrical, Pg 8-51 through 8-55, the "Voltage Limiter" which regulates the current to the instrument cluster is located INSIDE the fuel gauge itself. In the specific section that describes testing the Voltage Limiter to see if it is working, the manual says that if it IS NOT WORKING: "On Imperial models, the fuel gauge should be replaced." I couldn't find any info regarding replacing the voltage limiter ONLY; apparently the factory position was that you simply replaced the fuel gauge --which included the limiter. It *may* be possible to swap out the limiter only--if you remove the fuel gauge and can get into it without breaking it but I don't know anything about that, personally.

 Question from Cary:

Would anyone know what a fluctuating ammeter is indication of?  Not being an electrical whiz, I can only guess. I am thinking that perhaps my alternator is going bad--however it is barely 4 years old.  The gauge only fluctuates to the charging position--never to discharge.  The needle swings to "C" and is pegged there for quite a while.  This happens in my 70' LeBaron esp. in the cool morning air. Then once  she warms up on the road it hardly happens at all, although it is starting to be more frequent. I would hate to get stuck somewhere because of this. AND would doubly hate to have to leave her on the side of the road in search of a parts store.

Reply from Joe:

It sounds as though you have a bad voltage regulator. There are several things you should check before replacing it though. Trace the positive lead from the battery which has the fusible link in it. This is the smaller of the two wires coming from the + or positive terminal of the battery. You should find a small plastic (usually white nylon) connector which has latches which must be opened in order to unplug the connector. Unplug this connector and check the condition of the contacts inside. It should be free of corrosion. If there is corrosion, use a good contact cleaner spray lubricant such as that sold at TV service wholesalers for cleaning volume controls etc. on radios and TVs. Plug and unplug the connector several times and see if it cleans up sufficiently. Then when clean put back together with some yellow axle grease or some silicone grease if you prefer to keep out moisture. Also examine the heavy wire which exits the alternator on the other side of the engine. You may find a similar connector on that side of the engine. On some models the connector will be on the driver's side and on others it will be on the passenger side. This is the wire which the alternator output uses to charge the battery. If there is a poor connection anywhere along this conductor back to the battery, the voltage regulator will see low voltage and tell the alternator to increase its output. 

Another source of erratic charge indication is if the heavy black and red wires which go through the firewall at the large bulkhead connector get corrosion at the firewall plug. The symptoms are the same as noted before. Someone else mentioned loose connections at the ammeter. That should not be nearly as common unless the ammeter has been replaced. The large firewall bulkhead connector has several plugs and each has a latch associated with it. Be careful to unlatch it properly before tugging on the plug. Due to the age and heat it experiences under the hood the connector plastic becomes quite brittle. If it breaks when you unplug it, then the only easy repair is to visit a wrecking yard and try to find a similar connector on a somewhat newer car and get that and use it to replace the broken one. 

Each contact and wire in these connectors can be unlatched and pulled out the back side for detailed cleaning or replacement. A very tiny screwdriver is usually OK for depressing the contact latch so that it can be removed. Some experience with soldering and crimping wires is helpful in doing repairs to any of these connectors. If you don't feel confident about doing this find a good electrician or mechanic who is willing to tackle the job. Sometimes you can isolate a bad connector by starting the car and wiggling the various wires to different suspect connectors while someone watches the ammeter gauge. When you touch a wire or plug which causes a reaction that is the one at fault. 

As I said earlier, most of the problems develop because of age, heat and moisture. Another factor is that the largest heavy wire (such as to the ammeter) are going through the same size contacts as ones for much lower current flow. This often results in the contacts getting quite hot in operation. Over time this helps contribute to corrosion of the contacts. Sometimes after the process starts it accelerates to the point that the plastic connector body melts due to the heat. At this point it is almost ready to start a fire!! 

Most of the 69 and up Chrysler products all fall subject to these type problems. The older designs used connectors which had larger contact surface area and in many cases the connection was rubber sealed to the air helping prevent corrosion. Also some of the older designs had feed-through grommets for the charging current wires to the ammeter to pass through so there was no connection to go bad except possibly at the ammeter. Sometimes newer is not always better. Especially when the cost accountants dictate cheaper connectors over the objections of good electrical engineers.

This page last updated November 21, 2003.  Send us your feedback, and come join the Imperial Mailing List - Online Car Club