Assistance needed with a short or who knows what

[Bucolic]

My son has an '86 Chevy K-5 Blazer (CUCV), V-8 diesel, 24volt system. He had what we thought was a grounding problem as there were sparks showing up when he cranked the starter. Come to find out the starter was bad, the grounding strap from the solenoid to the starter body was not making good connections. We found this when we were installing a new starter.
The new starter works great, no sparks and it starts up immediately, just bump the starter and it's running. The problem now is, if you turn on the lights the horn honks. Black-outs work fine, but if you move the military switch up, into the service lights position, that's when the horn honks. We did NOT change anything. We disconnected the batteries to install the new starter and then reconnected them. NOTHING was changed, the truck was driven into the driveway an hour before all this work was started.
With it in this condition, he can't drive it as he has no brake lights or headlights for that matter.
After printing up the wiring diagrams and comparing what we've got to the print-out, no luck.
We spent a couple of hours unplugging stuff to try and find a short with no luck.
Anyone got any ideas??? We're going to leave it parked until we find out what's wrong.

 

[Warthog]

Remove the capacitor/noise suppressor at the horn.

 

[cpf240]

Bad diode on the horn relay, would be my guess...

 

[dmetalmiki]

That sounds like a faulty light switch unit. I would take out the switch and check it it out. You could whilst it's out take a hot wire wire to the plug ( sockect/connector ) and see what works one at a time. CHECK the earth wire first with a meter. You don't want to put a hot wire to that one. If you dont have an electrician handy to help just check one item at a time. Did you (allready) check fuses links and relays? Isn't it weired how motor vehicles break something else when you fix something else...maddening! keep us informed. others hopefully will step in with advice.

 

[Bucolic]

Ok, we found out if we left the light switch in the "OFF" position, toggles in neutral and the Chevy light switch pushed in, the horn didn't honk. With the key on, as soon as you turn on the lights, the horn honked. We replaced the horn relay, no change. We pulled the fuse for the horns, turned the key on and turned on the lights, no horn honk. All lights worked fine, the engine started and ran fine. No horn. As soon as the fuse was replaced, the horn would honk if the lights were on or got turned on. (The lights won't come on unless the key is in the "ON" position. This is normal)
Now what??

 

[Gottlos]

Well it wasn't the horn relay. Pulled the horn fuse and relay. Installed the new relay and was rewarded with a honk when the fuse made contact. Moving to the headlight switch and horn button area.

 

[doghead]

Read posts 3 & 4.

 

[MarcusOReallyus]

Read posts 3 & 4.

Why? Where's the fun in that? Spray and pray is so much more rewarding!

 

[Gottlos]

Read posts 3 & 4.

Now that I've read comments 3 & 4 several times I still don't know what the capacitor noise supressor or diode looks like. Got any pictures that might be of use?

 

[cpf240]

Now that I've read comments 3 & 4 several times I still don't know what the capacitor noise supressor or diode looks like. Got any pictures that might be of use?

http://www.steelsoldiers.com/showth...-Diodes-Relays&p=575716&viewfull=1#post575716

 

[doghead]

It's in the stickies, TMs and forums. All easily found with a search.

57 search results for "horn diode picture", here's just one. http://www.steelsoldiers.com/showthread.php?104746-Why-is-my-headlight-fuse-melting/page5

 

[Gottlos]

OK. I have now searched, looked around and read some. I will try cutting out the diode. After I put the horn button back together.