64 Valiant charging and lighting/gauge issues

[jedrattle]

I have a ‘64 Valiant that is having some weird electrical issues. I’m trying to get everything worked out so I can drive it to Tucson for the Roadkill Ziptie drags.

The electrical system pulses.
None of the dash lights work but fuses are good.
None of the gauges work expect for the amp (sometimes)

I’m thinking it’s a ground issues but want opinions/suggestions/ideas.

 

[67Dart273]

The ground "catch all" is over used LOL

The electrical system pulses.

This can be a number of things. It is often a bad connection in the harness causing the thing to form a slow oscillation or feedback. It can be a bad (going bad) original mechanical/ relay type voltage regulator. In rare cases can be the battery


None of the dash lights work but fuses are good.

The dash light circuit is a "trick." The power for the dash lamps comes from the tail / park circuit so they must work "first." That power is routed in the headlight switch through the dimmer control (twist to the left) and then fed down to the inst fuse in the fuse box. So the lights must be on, the tail circuit must be working, and the dimmer must be "some to the left" for that fuse to have power. If it has power and the lights still don't work, it's in the cluster............bad connections, bad bulbs, bad sockets/ connections


None of the gauges work expect for the amp (sometimes)

Ammeter: This could be because the gauge is "sticky" or it might be that the charging system is not working correctly. Normally, when the battery is charged/ normalized, the amp gauge should pretty much remain centered

Other gauges: I BELIEVE that year had the instrument voltage limiter/ regulator INSIDE the fuel gauge. Start by doing a search on this board there is hundreds of posts on gauges.

Go to MyMopar and download the closest year you can find for a service manual, and the aftermarket wiring diagrams there.

 

[RedFish]

Take the amp gauge out to visually inspect. It has a little round magnet in the middle that may have a collection of iron dirt on it. Compressed air to clear. Sad part is source of that debris. It pretty much had to come from the speedometer.

 

[jedrattle]

Thank you for the info.

The amp gauge goes from the center to the right. When it does this, everything flickers...the back ground in the stereo, the lights, etc..

I had no idea there was a regulator just for the gauges. I looked it up and it claims that it drops it to 6v for dimming the gauges. Does that sound right?

I did the headlight relay/wiring upgrade. That was a nice improvement. The taillights work and the turn signals but the flasher is kinda weak. I will check the connections on the bulbs for gauges.

 

[RedFish]

Does sound like a failing system voltage regulator.
The thermal gauges, temp, gas, oil, always were designed for 6 volts. So back when all the vehicles changed from 6 volt to 12 volt systems, most every mfgr simply added a mechanical voltage limiter for the same gauges ( GM is one exception ). Most cases this limiter is a small metal can thingy attached to the back of the inst' panel, Chrysler, Ford, VW, etc...
There are exceptions, including models where this limiter is housed inside a gauge. Early Imperials and others had it in their temp gauge. Other models have it inside the gas gauge. So....
Any gauge should require 2 electrical contacts, current in and out. If you find a gauge that has more than 2 contacts, it has something more in it. If your A-body fuel gauge has 3 contact posts, one of those is 12 volts going into the limiter. That 12 volts is chassis grounded via a small piece of metal on the back of the gauge,,, and like most everything else about the car, The instrument panel must be attached/grounded to the dash for it to work ( completes the ground path). Quite a few wires to a inst' panel and not one of them is a chassis ground wire. It's a good idea to add one, Comes in handy if/when you want to test bulbs, limiter, and such while the panel dangles from its harness connectors.

 

[Mattax]

The amp gauge goes from the center to the right. When it does this, everything flickers...the back ground in the stereo, the lights, etc..

The ammeter is not like the other gages in an important way. It directly measures the current flow to or from the battery. All the others measure change in resistance or voltage in a remote sender using the reduced regulated voltage.
When the ammeter swings to the right, it indicates battery charging.

(If the stereo was wired to the battery or starter relay, then the ammeter will show battery charging and stereo draw from the alternator.)

I had no idea there was a regulator just for the gauges. I looked it up and it claims that it drops it to 6v for dimming the gauges. Does that sound right?

No. Where did you read that? The factory service manual, and the Chrysler Tech Service info are good sources. 67Dart273 provided an accurate overview of the instrument illumination light circuit.

I did the headlight relay/wiring upgrade. That was a nice improvement. The taillights work and the turn signals but the flasher is kinda weak. I will check the connections on the bulbs for gauges.

The relays are on the headlights themselves. Markers are still fed through fused power feed into the headlight switch. Turn signals are powered from the ignition switched fuses.

 

[Mattax]

Soft flickering, just dimming a little - not on/off, could be ripple voltage from the alternator.

 

[jedrattle]

Soft flickering, just dimming a little - not on/off, could be ripple voltage from the alternator.

Thanks for the replies. I didn’t have the car when I posted this. I got it back from the shop on Thursday last week. I had to order a new voltage regulator (still waiting for it). I installed a new stereo on Saturday. When I installed the stereo, I discovered some wiring hack stuff. The constant power for the stereo was tapped to the horn power wire. Ground wires leading no where, loose wiring just laying there, etc.. I cleaned up that stuff and I drove it about 80 miles after that. At speed I don’t get a fluxuation on the amp gauge. It only happens at idle. I still need to pull the gauge panel out and look at things. I’m going to replace the voltage regulator, the belt and have the alternator rebuilt to 100amps (to help keep up with stereo system, when it’s finished). Along with a few more grounds. I think I know why gas gauge isn’t working but lost on the temp gauge.

 

[RedFish]

I'm going to guess "constant power to stereo" is memory of aftermarket head unit.
The horn power goes to the horn relay first. Another horn wire ( typically black ) is hot coming back inside to the horn switch. That switch grounds the wire which closes the relay and the horn blows. A ground path on this wire inside is supposed to close the relay and blow the horn. So if this is the wire that is tapped,,, Maybe there isn't enough current path through the stereos memory circuit to energize the relays coil.
It just doesn't seem right to me. I would sooner tap the 12V to cig' lighter well.
As for the temp gauge, both thermal gauges are supplied by the same inst' voltage limiter whether its inside the fuel gauge or plugged into the backside of inst' panel. If that limiter doesn't function, neither gauge functions.

 

[jedrattle]

You are correct on the stereo wires function. I didn’t do it, someone else did it. I ran a new wire for it. I’m thinking the voltage regulator for the gauges is shot. Trying to save some cash but it probably needs to be changed out. I have some more wiring stuff to do for the stereo later, so I’ll check that gauge stuff then.

 

[jedrattle]

Thank for the help so far!

I changed out the voltage regulator and hooked up my subwoofer amp. Now the amp gauge isn’t moving at all. I drove it around and ended up with a low battery. Got it back home and started looking at it. I tried disconnecting the sub amp...no change. I put the old regulator back in...no change. I’m thinking the sub amp killed the alternator by pulling too many amps.

So with all of that...I want to have the alternator bumped up to 80-100amps. I understand that’s a bit much for the stock wiring. I know I need to run some heavier gauge wiring to compensate for the increase in amps. My question is what wires? I feel I should bypass the factory amp gauge at this point, right?

 

[Mattax]

My question is what wires? I feel I should bypass the factory amp gauge at this point, right?

Seems like it already has been.
If everything was running on battery, the ammeter should have shown discharge.

Basic power feed and distribution:

Alternator feed provides power when the engine is running.
Battery feed provides power when the alternator is not running or the battery voltage is higher than the alternator's output voltage.

Alternator output goes to the main splice and then directly to whatever is drawing current.
Charging current then goes from the main splice to the ammeter and on to the battery until its satisfied.
-> When the battery is charged the ammeter shows zero because there is no current flowing through.

-> The ammeter shows discharge when equipment is drawing on the battery for power.

Its possible the ammeter is broken, its at least as likely the ammeter has been bypassed.
If the ammeters connections to the internal shunt fails, power will not flow through - nothing will run. The shunt is just a big metal plate. The studs are the connections.

 

[jedrattle]

With some help, I got it figured out. Yesterday I put in a 100amp alternator. No change. I was driving around and decided to stop by a friends house and out in the old voltage reg to see if that changes anything. The two of us were talking and I was explaining the issue to him. He starts trouble shooting it with a meter and discovers that the alternator is not charging. It was not being excited by the ignition wire. I installed a Mopar electronic ignition setup 2 weeks ago and that’s when the problem really started. What happened is, I unhooked the ignition wire for the voltage regulator. We found that out, hooked it up and it works! The amp
meter is showing charge. I’m still going to elimate the amp meter in the next couple of days but at least I got a new alternator, voltage regulator and no more problem!