Charging system problem

[VetteVet]

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[quote=mr.precision;8751497]Thank you for the detailed information.
The brown wire coming off the ignition switch was, indeed, disconnected. The odd thing is that it was connected to the two green wires at the base of the ignition switch plug. According the wiring diagram, that is for the temp idiot light. I don't have an idiot light for temp indicator.
[B][COLOR="Magenta"]

This was probably done by a previous owner. He may have changed the dash cluster to gauges from the light cluster. Connectiong the brown wire to the greens would make a path to ground through the sending unit, except that the resistance of the sending unit would prevent a direct short and burning of the wires.There should be two brown wires on the key switch for the brake warning light that check it when the key switch is placed in start. The key switch grounds them to turn on the light when the key is placed in start.

I checked continuity for this brown wire at both ends, disconnected from the regulator. All good. I also installed a new ignition switch plug as the old one was in really bad shape.

Years of having all the trucks current running through this connector will do that, it is very common and is the reason newer cars and truck use the ignition switch to turn on relays for the electrical circuits


Concern now is that the regulator connection for the brown resistance wire is showing a chassis ground. Not the wire itself....just the terminal at the regulator.

You are probably reading through the points wiring to ground, are you showing a small resistance?






If that terminal is grounded, does this indicate the regulator is bad? Perhaps manually closing the points with this wire hooked up fried something in the regulator.
No- See above

[mr.precision]

Problem finally solved.
Thanks to VetteVet for his patience in walking me through this.

The regulator terminal to brown wire is indeed grounded. Resistance is 4-5 ohms.

I went back over everything to check continuity and proper connections. I even took the new (Made in china) alternator off for an inspection. The ground stud on the back was loose in the case. It had not been snugged down during fabrication. This created an intermittant disconnect to the case, and therefore the ground. I had been checking all ground points, including the stud, but never the case.
This was verified using my meter to test for resistance to ground.
Didn't expect this discovery to be a solution, but put the alternator back in and tested the system. 13.5 volts at idle with a maximum charge rate of 14.8v.
Wish I had kept the old AC Delco core exchange alternator as there was probably nothing wrong with it.
As with many repair mysteries, it's a combination of several things that makes a fix difficult to diagnose.
Again, thanks for the help.

[VetteVet]

Thanks for the feedback and I would like to thank all the guys for input as well.