I was wondering if anyone could point me in the right direction.

I have an 82 F150 that I recently aquired. The charge light stays on all the time, even though with my multimeter the battery voltage reads approx 12v and I'm getting right around 14v with the engine running at idle.

I've replaced the voltage regulator and redid some horribly bad stereo and accessory wiring done by the previous owner, as well as unwired and removed a similarly terribly installed trailer brake actuator. I also replaced the wiring to the dome light after a small electrical fire (!!!!!) happened because someone riveted a patch over a rust hole in the driverside floorpan, and just happened to smash the wires under the patch (genious in motion). Of course, they also had a 20amp fuse on the interior light, so it took a minute to pop. (voltage reg was replaced after this dead short) As far as I can tell, I've undone anything wierd that the previous owner did. I'm pretty sure I have everything back to factory as far as the electrical goes.

I'm not having any electrical problems anymore, and the charging system seems to be working fine. Battery charges when running and holds charge, voltages look good, truck starts well. The only thing that I see at all is a slight pulsation in the interior light/dash lights/and stereo display when at idle. But this doesn't seem out of the ordinary on an older vehicle.

Any ideas on what could be wrong?

Thanks for any help,
UglyCoyote

 

Assuming your alternator and regulator are functioning properly, the next procedure is to check for a loose connection or short to ground between the battery feed and the voltage regulator terminal "l".

 

Thanks

I will check that tomorrow. Also, when I replaced the regulator, i noticed a small cylindrical thing connected to one of the wires. It was mounted directly below the regulator. It was too dirty/rusty for me to be able to tell if there was any labeling on it. Any idea what that may be?

 

That rusted small cylindrical thing connected to one of the wires was most likely the radio noise capacitor...

 

I think there is a difference in the alternators and/or voltage regulators used on trucks with gauges and those without (idiot lights) and are not interchangeable. Maybe somebody put in the wrong unit.
Piffery1

 

The connector that plugs into the regulator is different between the gauge and the light versions. I know this. Have owned trucks with both gauges and lights.

Best of luck. As you know, there is no better truck than a 80-86 Ford.

 

It wouldn't be the first vehicle I have seen with the charge light on and no problems to be found. Double check your grounds though, may have something to do with your lights dimming at idle. My wifes 79 Capri used to do that and I had accepted it until I took it in for some electrical repairs, and it didn't do it anymore when I got it back.

 

According to my '83 Ford shop manual the warning light is fed from the ignition switch run terminal and is turned "off" by an indicator switch internal to the voltage regulator. The indicator switch is "closed" (provides a ground) when the alternator is not charging, thus turning "on" the indicator and the switch is "open" (ground removed) when the alternator is charging. Wire 904 (Light Green with Red stripe) is routed from the instrument cluster connector to Terminal "I" on the Voltage Regulator. A ground or "short" any where on this wire will cause the indicator lamp to illuminate any time the ignition switch is "on" but should not have any effect on the charge circuit.
Piffery1

 

Double check that lite green/red tracer wire. It caused me to suspect my '84 charging system for awhile. Turns out that the small black connector near the regulator in the green/red tracer wire circuit was intermittent and caused the light to flash, usually at night.. I cleaned the contacts, and it never acted up again.

 

Another thought: With the ignition switch "off", unplug the regulator connector from the regulator; turn ignition switch "on", if charge indicator still illuminates-then the problem is a "short" in the LG/R wire circuit. If it doesn't illuminate-the problem is in the regulator itself (i.e., the internal indicator switch portion).
Piffery1