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Light Contoller non functional (no lights)

Posted: Tue May 19, 2020 2:13 pm
by mrvtwin95
Team, I was installing some new gauges and removed the instrument panel. I am not sure what happened but when I buttoned everything up none of my lights work (headlights, turn signals etc.) I am thinking its one of the circuit breakers bolted to the inside of the dash . From top to bottom can somebody provide the info indicating what breaker is for what? Thanks in advance.

Re: Light Contoller non functional (no lights)

Posted: Tue May 19, 2020 4:44 pm
by hambone
Check to see if you have power on # 15 coming into light switch, A1 or A2?

Re: Light Contoller non functional (no lights)

Posted: Tue May 19, 2020 5:33 pm
by Rickf
Those breakers do not power the headlight switch. The headlight switch gets power directly from the starter switch. The #5 wire that powers the whole system also powers the headlight switch. There is a breaker inside the switch. Hold the switch lockout in the lockout position and run the selector switch back and forth through the entire range a few times. Not real slow, up-down, up-down. These are mechanical switches with slide contacts and sometimes the contacts get dirty and this will clean them off.Do you have power to the volt meter? or the ignition? Will it start?

Re: Light Contoller non functional (no lights)

Posted: Fri May 22, 2020 12:10 am
by mrvtwin95
First, it is an A1 but, I must also tell you all that I have the push button light switch that you see on the M998. The truck will start just no lights. I am going to check the wires specifically number 5 and 15. Thanks guys.

Re: Light Contoller non functional (no lights)

Posted: Fri May 22, 2020 5:49 am
by svramselaar
hi

the wire no 5 (thin one at the starter switch ) is at the switch no 15 power for all
it is a open door bud have you set the switch at serv drive
have you the extra wire at the ground
https://olive-drab.com/images/push_butt ... itch_3.jpg
https://olive-drab.com/images/push_butt ... itch_4.jpg

let us know the answer

george

Re: Light Contoller non functional (no lights)

Posted: Fri May 22, 2020 7:31 pm
by mrvtwin95
I have to start by saying that at one time the push button light switch was working. I took out the instrument panel and reinstalled. Everything went south right after that. The whole front harness has been fooled with by whoever I suppose 40 plus years ago so things appear not to be wired like they should. The horn is wired directly to the battery and so on. I am looking to focus on what's behind the instrument panel....and go from there.

Re: Light Contoller non functional (no lights)

Posted: Sat May 23, 2020 1:19 am
by markrdje
I can remember reading along time ago the push button light switch goes bad alot, I bought 1 a long time ago, never did work.But maybe now they are better.

Re: Light Contoller non functional (no lights)

Posted: Sat May 23, 2020 6:12 am
by Rickf
You need to get the wiring diagram for the A1 and follow that and get things straightened out according to that.

Re: Light Contoller non functional (no lights)

Posted: Sat May 23, 2020 11:46 am
by Fil Bonica
Sounds like you may have basic problems with the harness.
Not to say you dont also have a defective light switch also but as Rick says study the wiring diagram to see if you can find any glitches first before you lay it on the light switch.
Been running the digital light switch in two A2s for al least 15 years and no problems.

Fil Bonica

Re: Light Contoller non functional (no lights)

Posted: Sat May 23, 2020 5:50 pm
by Rickf
So according to the diagram that George showed that light has to have a separate ground added to it. It is possible that people are getting by with the mounting screws making the ground but if they loosen or corrode then the switch will quit from what I see. Digital is very sensitive to grounds and resistance.

Re: Light Contoller non functional (no lights)

Posted: Sun May 24, 2020 4:41 am
by D Pizzoferrato
When these switches first came out, they did not have a ground wire and were very prone to failure, sometimes like a Lucas product releasing the magic smoke. There was a bulletin or MWO put out to add an external ground wire connection to alleviate the failure problem. Subsequent production had the ground wire as part of the kit.