dskupi01
Member
- 39
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- 8
- Location
- Detroit, mi
Here’s my experience with no headlights. All other light settings worked for me except the service light setting, specifically headlights. I had power at pin F in the lamp switch (obvious since other light settings worked).
I then pulled the lamp switch. I checked the switch from F to M (headlight) pins with the service light setting. No continuity. Lamp switch bad.
With the plug side sitting there, I shunted the F to M plug holes (female side) with a piece of thick wire to get the headlights to light up. Mistake. I found the root cause of the problem. The wire turned red hot instantly. A short to ground at pin M, when it should have fed the headlights. This short was what melted the lamp switch (a secondary failure). From my view of the wiring diagram, I see no fuses. I guess the Humvee doesn't have them.
I then began the process of finding the short between pin M at the lamp switch connector and the headlights. Took out high beam switch to start. There was a short to the switch housing (ground) on the switch from two of the three connectors. Cut open, it was a melted mess. Cut open lamp switch, it was melted also.
Now, I need to prepare for the new switches, so I don’t melt them. I tested high-beam output wires for short to ground with the hood connector removed (if not you’d short through the headlights). No short. Okay. Disconnected headlights, tested for short to ground with hood connector attached. No short. Okay.
I’ll replace both switches tomorrow. To be safe, I will feed the headlights prior to installing the switches with 24V wire with a low amp fuse to start. If it blows, more work to ID the short, and I will post a follow up. For now, I think the high beam switch was the primary failed part.
Any other recommendations prior to replacing the switch. I also still don't understand why there are no fuses? Am I wrong on this?
I then pulled the lamp switch. I checked the switch from F to M (headlight) pins with the service light setting. No continuity. Lamp switch bad.
With the plug side sitting there, I shunted the F to M plug holes (female side) with a piece of thick wire to get the headlights to light up. Mistake. I found the root cause of the problem. The wire turned red hot instantly. A short to ground at pin M, when it should have fed the headlights. This short was what melted the lamp switch (a secondary failure). From my view of the wiring diagram, I see no fuses. I guess the Humvee doesn't have them.
I then began the process of finding the short between pin M at the lamp switch connector and the headlights. Took out high beam switch to start. There was a short to the switch housing (ground) on the switch from two of the three connectors. Cut open, it was a melted mess. Cut open lamp switch, it was melted also.
Now, I need to prepare for the new switches, so I don’t melt them. I tested high-beam output wires for short to ground with the hood connector removed (if not you’d short through the headlights). No short. Okay. Disconnected headlights, tested for short to ground with hood connector attached. No short. Okay.
I’ll replace both switches tomorrow. To be safe, I will feed the headlights prior to installing the switches with 24V wire with a low amp fuse to start. If it blows, more work to ID the short, and I will post a follow up. For now, I think the high beam switch was the primary failed part.
Any other recommendations prior to replacing the switch. I also still don't understand why there are no fuses? Am I wrong on this?
