m1008 no power to horn fuse

[Wintergreen 86]

Im trying to get my m1008 inspected and registered. Im up in canada and one of the things they need is a horn. i have a new horn and relay, but horn doesnt sound, relay just clicks.

no power on the orange wire and dont seem to have power to the horn fuse. i have power at the ignition fuse.

Does this have something to do with the blackout system? Been looking to see how the black out system cuts power to the horn in my TMs but havent figured this out so far.

 

[MarcusOReallyus]

Welcome aboard, ya dumb kanncuck! (I have an uncle who was an RCMP in your town, and I was born near Toronto )

If your other lights are working, the BO system is probably not the culprit. Since you aren't getting power TO the fuse, that's the place I'd start looking. I've been looking in the TMs and I don't see any help there. The -20 just says to trace it back to the fuse box, and gives no further help.

Proably a good idea to pull the fuse box out and see what's going on behind.

You may have a problem with the connector through the firewall. It's a good idea to pull that apart and give it a good cleaning. It's probably gunked up with a black, gooey preservative that GM used. Kerosene does a pretty good job of cleaning it, and doesn't seem to hurt the plastic. It's a tedious job, but it needs to be done. I'd follow up the kerosene with some quality contact cleaner, then a contact lubricant.

This probably won't help, but just in case, here's the horn wiring diagram. By the way, you can lose the horn relay diode and the suppressor. They are not needed, and have been known to cause problems.

 

[Wintergreen 86]

thanks, pulling off the fuse box was my next step. black out lights work, service lights work.

diode is probably still there as the factory wrap appears to be intact, but i think the suppressor is gone already. least i didnt see it. this had no horn and gutted horn contact when i got it.

 

[porkysplace]

thanks, pulling off the fuse box was my next step. black out lights work, service lights work.

diode is probably still there as the factory wrap appears to be intact, but i think the suppressor is gone already. least i didnt see it. this had no horn and gutted horn contact when i got it.

You might want to read through this ;
[h=1]CUCV Helpful Threads[/h]

 

[cucvrus]

I am thinking the horn is bad. Best thing to do is remove the left headlamp/bucket and get in there and unplug the horn. Check that resistor in the horn wire also. Could be as simple as a ground. The horn is grounded thru the mounting bolt on the core support. If it is making the clicking sound it is getting a signal. Check to see if it is sending power out to the horn. Seems easy enough. Good Luck.

 

[Wintergreen 86]

You might want to read through this ;
CUCV Helpful Threads

thanks, i have found those already though and have been looking at them.

I am thinking the horn is bad. Best thing to do is remove the left headlamp/bucket and get in there and unplug the horn. Check that resistor in the horn wire also. Could be as simple as a ground. The horn is grounded thru the mounting bolt on the core support. If it is making the clicking sound it is getting a signal. Check to see if it is sending power out to the horn. Seems easy enough. Good Luck.

horn is good. it is brand new and i have jumped it with direct 12v and it works. i am not getting any power from the horn fuse.

 

[Wintergreen 86]

Cleaned the firewall connector and reassembled. Most of the fuses were wrong so I changed them out. That got me power to the circuit.

Still didn't work. Turns out my new relay was bad or wrong. Changed that and it is working now.

 

[MarcusOReallyus]

Nice work! This is a classic example of good troubleshooting. Doing the basics (cleaning connections, checking fuses) was needed before you could get to the other problem, the relay.

Also a good lesson in assumptions - new parts are always good, right? Yeah, right!

Thanks for closing the loop on this.

 

[Wintergreen 86]

well now my brake lights stopped working. also missing half of a reverse light socket. here we go again. guess it isnt getting inspected tomorrow. oh well time for a beer

 

[porkysplace]

well now my brake lights stopped working. also missing half of a reverse light socket. here we go again. guess it isnt getting inspected tomorrow. oh well time for a beer

Did you bump the blackout light switch ?

 

[Wintergreen 86]

Did you bump the blackout light switch ?

if you mean the wiring connector, it is very possible. ill make sure it is secure later. but the switch itself is on the service light setting, i was driving around with my headlights on, signals etc, worked.

 

[Wintergreen 86]

And that was exactly what it was. black out switch being finicky. getting closer now.

 

[cucvrus]

Now wait a minute here. The relay would not be clicking if the black out switch was the issue. With the switch in B/O the relay gets no signal. I am not an electrical genius but I do know the signal goes from the clicking relay to the horn. Not back thru the B/O switch. Come on you have other issues. obi wan Kenobi where are you?

 

[Wintergreen 86]

Now wait a minute here. The relay would not be clicking if the black out switch was the issue. With the switch in B/O the relay gets no signal. I am not an electrical genius but I do know the signal goes from the clicking relay to the horn. Not back thru the B/O switch. Come on you have other issues. obi wan Kenobi where are you?

You may have misunderstood. These were 2 different things. Horn is fixed now. The black switch was causing issues with the brake lights.

Still have some thing s to deal with but the truck was inspected yesterday and passed. It is now registered, insured, and on the road.

 

[cucvrus]

The brake lights are the other fuse that is on the 30 amp fuse that runs the lights. If you have a hot 30 amp fuse midway up in the fuse box the only other fuse on that leg of the fuse box is the brake lights. Without being there I am guessing but I had that issue in the past. I was at the inspection station feeling all happy and they came out and said no brake lamps. I was pulled from the list and my vehicle was set aside. I quick went out and messed with a few wires and jacked 12 volt into the fuse blade and called the mechanic back outside. I showed him it had brake lights. He applied a sticker and I drove home removed the fuse box and tapped an in line fuse into the fuse box. My 30 amp leg was just crumbling slag from being overheated may times and I was pushing barbed spade connector in both sides of the outside fuse leg. Made heat more and more over time. I was so good at knowing when the fuse blew I could put my foot up there and just push around on the right side of the fuse box top correct the lighting issue. Worked for a long time then one day. No good. Good luck. I like to share and brain storm issues. It helps. Anything is possible given the right conditions.