OK, finally have truck running good, thanks to MANY folks on this forum. I still need to clean out the gas tank; cleaning the filter every few days is getting old fast.
Anyway, here's my issue. This truck has an idiot light for the alternator, but a PO also installed an aftermarket voltmeter. The idiot light in the dash turns on and off at seemingly random times, but the voltmeter holds solid at just under 14 volts. I have verified it's reading with a DMM. All of the wiring diagrams I have (emailed to me by some gracious folks on this forum) all show the schematics for a truck with an ammeter. My question is, what turns on the idiot light? Granted, I can always use my voltmeter, but I like having the idiot light to call my attention to it, in case I'm not paying attention, and I'd like to have it working correctly.

Also, how is the switch in the door wired into the dome light circuit? There is only a single positive lead going to the dome light, and the switch in the door seems to only provide a ground.


Thanks!!

 

Bueller? Anybody?

 

The idiot light is connected straight to the "I" terminal on the voltage regulator (I believe the red/green wire).

If alternator is good, and all connections & grounds are good, I'd replace the voltage regulator... the last one I bought was about $10 and it solved a problem where my idiot light was flickering on.

 

Tracing electrical gremlins can be a pain in the backside, that being said, the 65 Ford Truck Wiring Manual does not show there's a dome light switch at the door, not to say one does not exist, am sure another member will point it out if there is. Diag. shows the dome light circuit consist of a single wire running from headlight switch to the dome light and is either grounded thru the mounting screws, or a separate ground wire. Sounds like prior owner may have installed the door switch and since I have not clue posting a link to 65 Falcon wiring diag. that includes the door switch, not sure if it will be helpful, would seem for the dome light switch, and door switch to work independent they would have to have a common ground, likely member familiar with the application can advise.

http://www.tocmp.com/tOCMP/wiring/57...re5765-190.jpg

Not familiar with the 'volt meter' circuit, but since the 1 indicator is steady and the other fluctuates, as jmf66 noted, check the circuit for breaks or poor ground, and if this does not correct problem then replace regulator. Would also include cleaning connectors and connections at regulator and lamp. Recently purchased an expensive wiper switch to find only needed to clean connection at the switch.

For info purposes: Small section in shop manual: with Ign switch on, current flows thru indicator light and 15-olm resister thru the regulator voltage limiter contacts to the field coil. When alt. builds enough voltage to close the field relay contact then full voltage is applied to the field and indicator light goes out. Anyhow, if isolate problem to regulator would not fiddle with it, just replace.

 

OK, it was a loose connection at the I terminal on the regulator that was making the Alt light come on...Thanks JMF.
Thanks for the link, Dve! That is what I would expect it to look like, and I figured like you figured, that they'd have to tie together, but not on this one. I can't figure how they'd do it by only providing a ground from the door, and only providing a positive lead to the light. The switches look factory, but maybe like you said, somebody started to modify it, but then couldn't figure out how to do it. If I need to, I'll just wire in a relay and be done with it.

Anybody else know if a 66 F100 came with door jamb switches?