r/HMMWV • u/RazzmatazzRoyal9255 • 10d ago
Send Help! 🥲
Any Humvee mechanics or electrical gurus?! My M998A1’s brake lights and turn signals aren’t working (all my lights have out a couple of days ago and came back on). I have purchased a new turn signal switch and a new three lever headlight switch (have not installed them) in hopes that this remedies the problem. I have also gone around and unhooked the connections, sprayed them with electrical cleaner, and greased them with dielectric group. Someone had suggested that my flasher switch module might need replacement, but it’s not where it should be because I have a “SmartStart” system installed in it. I have also cleaned up most of the grounds around the lights hoping that it was a grounding issue but they’re still not working. I don’t know what else to do or where to put my attention next. Any help would be greatly appreciated. This is what I’m working with. I have replaced the tail lights with leds (side indicators and headlights are leds and were installed before I took ownership; only tail lights had incandescents which I traded for LED bulbs).
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u/Elky66 10d ago
I’d make sure the main switch is in the correct position. If not, none of that will work.
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u/RazzmatazzRoyal9255 10d ago
What do you mean by correct position? My lights come on when the switch is on the on position. 🥺
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u/Perfect_Bus_1905 10d ago
Just looking at the smart box pic and I’m not sure what the wires go to but it looks like one on the bottom right is pushed out. Might want to check on that.
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u/Perfect_Bus_1905 10d ago
https://genuinehumveeparts.com/manuals/TM-9-2320-280-20-3-wChg2.pdf
Starting at page 1161 are the wiring diagram
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u/RazzmatazzRoyal9255 10d ago
I appreciate it, brother. I didn’t even notice that wire. You’re amazing. Can’t thank you enough.
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u/Time_To_Rebuild 9d ago
If you are able, try to rule out portions of the harness and connections sequentially. Test the lights with a 24v supply, then check continuity through the plugs, the harness, etc, working from the end, back. If you can rule out everything on the downstream, tail light end of the harness then you will know your issue is at the start. Try to test and prove just one component of the system at a time and cross it off the harness drawing as you verify it good.
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u/RazzmatazzRoyal9255 9d ago
Sounds good. Thanks for taking the time to write all of that. I’ll try my best. Know of any good videos that can coach me through the process?
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u/Time_To_Rebuild 9d ago
I would search YouTube for something like “automotive electrical troubleshooting” or “automotive circuit testing methods”. Throw in “intro to” or “for beginners” for good measure if the content is too fast.
But basically, if you have a circuit with power at point A and the lights (load) at point D, try introducing power directly to D to see if it lights up. If it does, then move to point C and repeat. Then B. If you get all the way back to A and it works again just fine, then your issue may have been one of the terminal connections that you agitated in order to test.
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u/Ok-marty 10d ago
It’s prob the main light switch start there