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Switch heating up, ammeter going crazy. Help!

cruiser

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Hi Guys/Gals. Just ran into a problem with my 69 Charger last night. The car has been restored and is very stock. I was driving for about an hour just before dusk. I had the headlights on, with high beam selected. 35 minutes into my drive, I noticed the ammeter needle dancing around, varying rapidly between plus or minus 10 amps. It would do this for several moments, stop and then start again. I also noticed that the headlight switch was noticeably warm, almost hot to the touch. It's usually not warm or hot to the touch. The moment I turned off the headlights, the ammeter read normally and stayed that way as long as the lights were off. The instrument cluster has been rebuilt with a solid state voltage limiter, and the engine has the electronic ignition conversion with an electronic voltage regulator. The foot dimmer switch was replaced several years ago. The headlight switch is a NOS one installed about 25 years ago. So what's going on? Any and all ideas are welcome. Thanks!
 
Hi Guys/Gals. Just ran into a problem with my 69 Charger last night. The car has been restored and is very stock. I was driving for about an hour just before dusk. I had the headlights on, with high beam selected. 35 minutes into my drive, I noticed the ammeter needle dancing around, varying rapidly between plus or minus 10 amps. It would do this for several moments, stop and then start again. I also noticed that the headlight switch was noticeably warm, almost hot to the touch. It's usually not warm or hot to the touch. The moment I turned off the headlights, the ammeter read normally and stayed that way as long as the lights were off. The instrument cluster has been rebuilt with a solid state voltage limiter, and the engine has the electronic ignition conversion with an electronic voltage regulator. The foot dimmer switch was replaced several years ago. The headlight switch is a NOS one installed about 25 years ago. So what's going on? Any and all ideas are welcome. Thanks!
Check the terminal housing under the foot switch....I had one melt a few years ago....full current passes through that switch, and they get damp, hence potential problems.

Also check the terminals on the back of the headlight switch....heat normally points to a loose terminal - maybe one of the female receptacles is a bit loose.....can be closed up easy with needle-nose pliers for a tighter fit.
 
Better call Scotty! Sounds like she's gonna blow anytime, Keptin.
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you can jump out the green wire to the violet ( low beams ) or the red ( high beams ) wires to check for heat on the jumper wire conection or anywhere else along the circuit. That bypasses the dimmer switch as a posible problem, such as an internal contact failure.

With engine running and as far alt gets a good power rate ( into the stock specs ), the ammeter could read a slight discharge at iddle, but no 10 amps. that's too much for just two headlights ( lows ). But a contact failure could increase the discharge being sucked/dissipatted as heat on the bad contact.

Highbeams could be close to that reading thought, once again depending on alt capacity. This is the critical point. With engine off high beams being 4 sits close to 10 amps and ammeter will correctly register that, but with engine running, the alt should feed totally or partially that, so the ammeter shouldn't show 10 amps discharge on that stage. This doesn't mean the high beams are not sucking 10 amps, but just all that load is being sucked just from batt being discharged, when the alt should cover that and amm show as far as posible zero or minimal discharge. The ideal stage.
 
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Need to correct myself... I was thinking on a floor dimmer switch failure... if headlight switch you could also jump out the thick black wire ( 12 gauge as far I recall ) reaching the switch with the light green wire. That will bypass the switch itself, just to check if reading remains the same.

You could find also the headlight switch plug burnt/melt if so. I have seen many of them melted down at the black wire cavity.

these both replies are just an idea to track the problem, not saying or stablishing THERE is the problem.

Another place to check... black alt wire at bulkhead, burnt, melt etc... A failed conection there could get you on discharge stage anywhere/anytime
 
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You might want to consider running the headlights direct from the battery via a relay. That way the electrical load will be taken off the switch.
 
You might want to consider running the headlights direct from the battery via a relay. That way the electrical load will be taken off the switch.
Cars with ammeter NEVER must get any accesory/device feeded from batt. Everything MUST be sourced from alt.

Ok on the relay upgrade but not from batt.

then ppl wonders again, and again, and again why ammeters and bulkhead failures, blaming the system.

Know the system before proceed with upgrades is the most important part here

Still with the relay, charging system/wiring must be checked now the failure floated on.
 
Cars with ammeter NEVER must get any accesory/device feeded from batt. Everything MUST be sourced from alt. WHY ?? WHAT IS THE DETERMINING FACTOR ??
Ok on the relay upgrade but not from batt. WHY?

then ppl wonders again, and again, and again why ammeters and bulkhead failures, blaming the system. PLEASE EXPLAIN YOUR THOUGHT PROCESS

Know the system before proceed with upgrades is the most important part here WHO OR WHAT MAKES THE DETERMINATION OF HOW TO PROCEED?

Still with the relay, charging system/wiring must be checked now the failure floated on.
HOW OR WHAT IS MEANT BY "FAILURE FLOATED ON"? Sounds like an intangible aspect.....how do you fix an "intangible"?
Perhaps, you can supply some calculations or specific examples to support your position rather than something unsubstantiated. Inquiring minds want to know.....
BOB RENTON
 
What is the ammeter designed to measure?
Does the battery run the car with the engine on? That might help with why the alternator source and not the battery with an ammeter. If you want to see excessive charge on ammeter with headlights on while driving, battery it is. Taxing the ammeter and bulkhead (second pass) with that load.

JMO for the OP. Turn the switch to the on position, disconnect the plug at your dimmer switch, drive around for a hour or so... is the switch hot? Helps narrow the area of your issue.

Relays are the best way to protect the OEM headlight switch and harness from damage from heat and resistance in the circuit.
 
Hi Guys/Gals. Just ran into a problem with my 69 Charger last night. The car has been restored and is very stock. I was driving for about an hour just before dusk. I had the headlights on, with high beam selected. 35 minutes into my drive, I noticed the ammeter needle dancing around, varying rapidly between plus or minus 10 amps. It would do this for several moments, stop and then start again. I also noticed that the headlight switch was noticeably warm, almost hot to the touch. It's usually not warm or hot to the touch. The moment I turned off the headlights, the ammeter read normally and stayed that way as long as the lights were off. The instrument cluster has been rebuilt with a solid state voltage limiter, and the engine has the electronic ignition conversion with an electronic voltage regulator. The foot dimmer switch was replaced several years ago. The headlight switch is a NOS one installed about 25 years ago. So what's going on? Any and all ideas are welcome. Thanks!
Any update on this?
 
On the first link posted I'M NOT recomending the amm bypass, just right the opposite saying you can live with it, but just save the bulkhead path. And explain what the reading means on every stage.

And WHY NOT the batt must be used as a main source for CONSTANT power sourcing, causing an "unreal" amm reading and unnecesary stress to the gauge. ( and bulkhead paths )
 
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