Gremlins afoot-1997 M1078 A0

[rafique_edwards]

back on the crazy train

Having an issue :

symptoms are horn not working when you press the button. I can hear the relay click
headlights dont turn on
directional dont illuminate outside but on dash it flashes. can hear relay click
wipers work
Check relays- looks good
i swapped the stalk with no luck
thinking it may have something to go the 3 level light switch I swapped with no luck.

point me in the right direction before i go Captain Caveman

 

[hike]

I don't know what a 3 level light switch is. It looks like all you describe may run through P18 connection in the steering column?

 

[rafique_edwards]

I don't know what a 3 level light switch is. It looks like all you describe may run through P18 connection in the steering column?

Type-o. Meant lever not level. The 3 lever light switch

 

[GeneralDisorder]

Start cleaning grounds. Replace all CB's with fuses. Replace all relays with new ones. Pay attention to 12/24, 5 pin / 4 pin, and integrated resistors, etc.

30 years is a bridge too far for the military grounding system. Remember CARC is not particularly good at shedding water from getting into electrical connections because the military way is to use a star washers to pierce the paint and then *maybe* cover it with silicone or paint. Or not. Regardless, corrosion and poor connections are the result and they cause basically ALL of these rando electrical issues people have. When there's a lack of ground, circuits will FIND a ground through something else - often causing unpredictable behavior like when my alternator would drive itself to 32v and shut down. That was a ground problem causing LBCD capacitors to discharge into the field circuit - driving the voltage high and causing the VR to shut down.

 

[Ronmar]

30 minutes was a bridge too far for the way S&S did these grounds

When i get home I can put up a 1 page drawing of the A0 lighting system that may help you look for clues/answers...

Pay attention to the 4-5 pin relay differences General alluded to. If i recall there is one of those in the lighting circuitry and if a 4 pin gets put in that socket, it won't work right... Don't know who the knucklehead was who didn't simply make them all 5 pin, but he should have been used as a speedbump during testing... easy way to tell is if the socket actually has 5 spade terminals in the holes, it requires a 5 pin relay... but you can put 5 pin relays in any socket, so only buy 5 pin relays...

Clicking and dash arrows are good as those are near the end of the circuit, and also indicate the flasher is operational. The clicking are relays K30 & K31 if I recall. They are not used for the basic truck signals and provide 24V commercial trailer signal lighting(powered by 12v flash sig and switch 24v to trailer) to the commercial 10 pin trailer plug. You can pull them if you don't plan on pulling a commercial trailer(not many of us ever will)...

 

[GeneralDisorder]

But sir! 4 pin relays are $0.50 cheaper!!

Still fired..... To the suspension testing room with you!