Okay, before anyone else says it, yes, I'm an idiot. Now we have that out the way...
I've been trying to troubleshoot to figure out why my horn isn't working. Last night I thought I'd narrowed it down to the switch and then as I was looking at the wiring diagram my brain had a bright idea.
I figured if I jumped a wire from 30 to 87 on the horn relay base it would bypass the need for the solenoid to be triggered thus bypassing the need for the switch, and if everything else in the circuit was working the horns should sound.
So I just tried it and they didn't. (Was I wrong?)
Then, and now I've stopped to think about it I have no idea why, I decided to take that wire out and instead jump it from 85 to 86 and... puff... a cloud of smoke wafts from under my dash and I quickly turn off the ignition.
On closer inspection I've melted the brown wire (that haynes says should be brown/white) and the red/white wire that both go into the relay base. And I also noticed a brown wire attached to the ground by the fuse box has a blister in it too, although I'm not sure how those two things are connected?
So, what did I do and what do I need to do next? And why didn't fuse 8 pop and save me from myself?
Any advice much appreciated.
Thanks
John
the wire going to the horn button has battery on it from the horn relay. . the horn pad in the steering wheel grounds that battery when pushed. . that operates the horn relay. . the relay passes battery to the actual horns. . grounding the brown/white horn wire in the steering column horn pad should operate the horn relay. . even is the horns didn't operate, you should have heard the relay on the fuse panel click
No clickie then the circuit from the horn pad to the relay is bad. . . if you hear the relay click, then the wiring from the relay to the horn is bad. .
This is assuming no DAPO made wiring changes. .You might want to change the relay with a know good one first
When you jumped 85 to 86 you shorted out the coil of the horn relay. Same as shorting battery + to ground! With expected results, max amps and burned wires. There is another problem in your horn circuit that you need to find.
Fuse #8 didn't pop because the power to the horn relay #86 comes from the "hot" side of fuse #8, not the fused side.
When you jumped 30 to 87 on the horn relay, the horn should have sounded. If not, there is a problem with the wiring to the horn or the horn itself. It may be an open or a bad horn.
Tom
Thanks guys.
Before I engaged my brain incorrectly and hooked 86 to 85 these are the things I knew that made me suspect the switch:
1. The horns are new, I've tested them across the battery and they work.
2. The relay works - I switched it out with fog relay and the fogs still worked.
3. The relay base was getting 11.5V at terminal 30 with the ignition off and 30 and 86 with the ignition switched to ACC.
4. When I press the horn I do not hear the relay click.
I didn't check the hot wire at the horn, but from what you're saying it should read 11-12V even with the ignition off, right?
I haven't tried grounding the brown/white horn wire into the switch, I'll give that a try once I've fixed the frazzled wiring. Which leads me back onto the frazzled wiring...
Will the damage be localized around the relay or do I need to check the entire length of each of the wires - brown/white and red/white?
And how the hell do you get into the rubber relay bases that hold the female terminals to check the wire connections? Is it even possible, mine seem to be a single piece of molded rubber.
John77,
No, you won't get power to the horn hot side with the ignition switch to off. J-13 needs to be energized. Turning the ignition switch to on should energize J-13. It must be working if you have had power to #86 of the horn relay.
As to the damage being local, really hard to tell without seeing it first hand.
I have never had one of these sockets apart, but sockets like this usually have a special tool to release each contact from the socket, usually used from the front and the contact releases to the back side.
Tom
Attached thumbnail(s)
Tom, thanks for posting those diagrams, really appreciate it.
I checked the fried wires this morning and two things became apparent. Firstly, that I'm actually a bigger idiot than I thought - who knew? The relay I was attempting to kill wasn't even the horn relay After tracing and pulling the melted wires I discovered it was actually, as the Haynes manual calls it, 'Relay for fresh air fan.' So that would explain why the horn didn't sound when I jumped 30 to 87
And secondly, as far as I can see, the wiring gods were smiling and the two wires only melted to each other and didn't damage anything else. The brown just went straight to the ground next to the fuse panel, so that was simple enough to check. The red/white was fused to the brown in 4 or 5 places where they were touching, but so far I've traced at least another 6 inches of it up behind the dash where there's no visible damage.
Does anyone know where that wire terminates? It disappears into spaghetti behind the dash and I'm finding it difficult to follow it. In the Haynes manual the red/white comes out of the 86 on the relay and immediately stops with a number 14 at the end of it, but I have no idea what 14 means.
Also, I have no heater as my car's a 6 conversion and the exchangers have been swapped out for headers so I'm a little confused as to why it's wired up. Could I just cut and tape off the end of the hot red/white wire and leave it without it effecting any other circuits?
Look on the other page of the diagram for a little number 14 with a red/white wire.
Basically, it carries switched power. It's probably coming from the ignition switch.
The relay in question provides switched power to a bunch of things up in the dash, not just the fresh air blower. It's best to get the circuit fixed.
--DD
Jumping 30 to 87 on J-13 should not have resulted in what happened. Check 87 to ground and I expect you will find it grounded. You will need to trace out the wires that 87 feeds to find out why. Try pulling fuse 8 and see if the ground lessens. If so, the problem is probably down that track. If not, try removing J-4 and see what that does to the ground.
Tom
Even jumping 86 t0 85 on the horn relay should not result in fried wires UNTIL the horn button was pushed. It may be that the wire from J-4 pin 85 is grounded all of the time. Probably at the steering wheel.
When I first got my car, the horn would work sometimes. I finally found that J-13 was not always operating. Cleaning the socket and prongs and slightly spreading the prongs on the relay fixed that intermittent problem. Somehow my radio is hooked into that circuit also and it would not work when the horn would not work. That became my check to see if the horn was going to work, just turn on the radio.
Tom
Yes, if you jumped 86 to 85 on J-13, that would short key switched + to ground. In other words, if the jumper were there and one turned the key switch to ON, a direct short ( un-fused ) would happen. So no fuse to blow and the wire becomes the fuse.
Sorry if I also misunderstood, and hope you find the problem soon. Sounds like it is fairly localized. With our cars that is a very good thing.
Tom
Just had a chance to start troubleshooting my non-working horn again. I grounded the brown/wire on the back of the switch and the horn blasted, so that means the problem's with the switch, right?
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