Ground Problems

[Roger Friedrich]

Does anyone have any ideals about grounds on the M37? I replaced with new items the circuit breaker, the dimmer switch, new headlights, the 3 lever headlight switch and today I removed the ground wire from the front radiator support sanded it to bear metal as well as the solderless connectors then installed a new ground wire that tied into a ground from the battery. Still the headlights don't work. If I take the headlights to the batteries and touch the wires to the battery post then the headlight lights up. I never been good with electrical and it must be my continued jinx. Any ideals would be appreciated.

 

[JH1]

You can chase the problem ground with a test light. Put one terminal (point or ground clamp. Makes no difference if it is an incandescent bulb) on the ground side of the headlight and the other on the grill. If no light, then put one terminal on the grill and one on the frame. If no light, then put one terminal on the frame and one terminal on the negative battery terminal (not the clamp, but the central lead terminal of the battery, itself) and see if it lights. There should be no light anywhere, but if there is, it indicates that you have voltage between those two points. Wish we were closer. I'd just come over and do it.
JH1

You can also check for voltage between the actual battery terminal and the clamp on it. There could well be corrosion and no conductivity. Does anything else on the truck work right? Will the motor start? If it will start, your battery terminal clamps are fine.

 

[nattieleather]

Though Grounds on an MV can drive a man to drink you need to do a mythotical trouble shoot on your electrical. Like JK1 asked does the motor turn and start? Yes then batteries are good no fix battery issues. Do you have 24v on the the main lead to the headlights? Using a Volt Meter or 24V test light check the voltage at the light with a know good ground. If yes then check the ground on the headlight bucket make sure it's good. If no then you need to see if you have a wire problem and where do you loose the voltage. Is it a new wire harnes or and old one that might have breakes etc in it? Sometimes fixing these problems is like eating an elephant. One bite at a time.

 

[Roger Friedrich]

The M37 starts and runs good and the generator and voltage regulator has been checked. I get 24 volts at the plug in at he fender but when I plug in the headlights they don't work. When I attached the wires to the headlight spades is there one for the ground one for the low beam and one for the high beams?

 

[Stan]

Yes

 

[foxtrk2]

there are two separate connectors fop rhead lights in the orig wire harness on my 37 there was a bad connector under the wire harness cover under the front fender I found the second connector points so to confirm check those you should have one in the head light bucket one under the fender cover and one on the iner fender wall fo rthree total

 

[Roger Friedrich]

Good news I took the switch back out of the dash the removed the wiring harness fro the switch, unwrapped some of the black tape from the wire harness and what did I find The wire number 15 that feeds power from the circuit breaker was weaken with age and corrosion I replaced the bad section of wire and the head lights worked. I'm not sure what caused the section to develop corrosion but my problem is solved.

I want to Thank everyone who replied to my post and gave me suggestions