Total Recall

Hi, its a 92 lt1 coupe.

My horn does not work. I`ve checked things that ppl have posted on the forum but still can`t figure it out....

The alarm works, and the fuse is good.

I checked the steering wheel switches - and found that both sides of both switches were constantly earthed/grounded - though in theory that should mean that the horns sound all the time right?

Even holding the switch contacts miles appart from each other both sides of the switch/wires are grounded.

So i thought maybe it was getting a ground from a fault in the wiring itself or even a feed back from the relay.

Disconnected the relay - and no more grounding (except when you press the horn switch as it should). So I think that eliminates the wiring between the horn switch and relay.

Tried another relay and still the same problem - grounding all the time - but no horn sounding. So that eliminates the relay.


What else can it be? - it`s a bit hard to check the wiring after the relay as it goes way up behind the dash.

Does anyone have any idea what wires that go to the relay could be faulty to just cause it to feed back a ground to the relay and back to the horn switches terminal? (other than the 2 black steering wheel switch to relay wires which I`ve checked above).

for example if the relay itself didnt have power could that cause this?

There`s 5 terminals on the relay - where do they all go? I figure there must be 1 from thre alarm module, 1 from the horn switch, a power for the relay to work and a power wire to switch the horn - so that`s um 4, where does the 5th wire go?

Hope all that makes some sense. I always seem to get the non standard problems

Thanks for reading,

Dom

65Z01

On my '88 the alarm and horn switch drive the same horn relay.

If your Vette is the same and the alarm works, the problem is in:
- the horn switch,
- the slip ring or
- the wiring between there and the relay's black wire.

BTW, my horn relay has only three contacts:
-one with a pnk wire
-one with a grn wire
-one with two blk wires

Powersmokin

make sure you have a good ground on the steering column.

pipe

I also have a post going about this. The guy's on here tell me it's the connector behind the steering wheel. The steering wheel must be pulled. Pipe

Total Recall

Hi thanks, for the replies.

Going to do some more testing 2day.

The system must be a little different on my 92 then as my relay does have 5 terminals - my relay is under the RHS dash in the middle of a block of 3 relays.

I think the alarm works through the same relay though as on yours.

Thanks for the other replies, hope you get yours sorted out. I don`t use my horn much but I need it working to pass our yearly MOT test.

Will post back what I find out 2day.



Thanks,

Dom

toptechx6

My 93 wiring diagram shows a 4 terminal relay, terminals 30 and and 86 are the power wires from the fuse to the switching and load sides of the relay (green wire) always 12 volts.
Terminal 85 is the ground wires (black) from the horn switch and CCM (central control module)
Terminal 87 is the relay output wire to the horns (dk. green)

pcolt94

Two additional points of attack.

1) Check the horns for resistance or put 12 volts to them to make sure that they function.

2) Disconnect the horn wires and measure the voltage on it as you try to blow the horn from inside the car. Connect the red lead of the meter to the wire, and the black to engine ground and set the meter to DC volts. This will check out to see if the horn circuitry is working.

I just replaced the switches for the horn in the wheel for my 94 and was about $22 from GM.

Total Recall

Thanks so much for the wiring info - I can test and eliminate the wiring at the relay next

I have tested the wiring at the horn to c if it lights a test light which it didn`t - but didn`t think to check via a meter to c if it is giving any voltage at all - so will check that as well.

Didn`t get chance to do nything else 2day so will be 2moz now.


Thanks again,

Dom

65Z01

Very likely.
All the alarm or the horn button does (on my '88) is to ground the relay coil to activate the relay and apply power to the horns.

Ray Quayle

Hey Dom,
I can help you out. Where exactly are you? I'm near Harrogate.

Total Recall

Many thanks for the offer Ray - but I have just sorted sorted it!

I`m about 15 miles west of Hull. I see the odd Vette round here from time to time but never manage to meet up with any of them.

Do you go to the Leeds meet (2nd Sat of every month, Junction 1 M621 at Burger King?). Theres a gr8 selection of all American cars there when it`s nice weather.

Thanks again guys for your help. I ended up going through your advice and back to the start - turns out it was the horn connector behind the steering wheel after all!

Would have been sorted a few days ago if it hadn`t been for me confusing myself when testing it all out.

One thing that confused me was the horn wire being grounded even with the switch appart - turns out the other end of the wire had popped out of the connector and grounded on the steering columnl - which is why it had ground at the horn button - but not at the relay.

The other dumb thing b4 that was when I thought that removing the relay solved the problem of the horn switch being grounded all the time.

However I tested for ground/earth at the relay connector using the interior light power for my test bulb. Ofc what I didint realize was that the interior lights turn off after a while even with the doors open - which just coincided with me taking the relay out - and me thinking it had stopped grounding!

The dumbest thing of all though was that I couldn`t see to put the relay back in so I actually pressed the door button in and out to bring the lights back on so I could see where to put it - without even realising it would affect my test bulb - so when I put the relay back in and double checked the wire for ground again - the test bulb light again. Doh!

Well that`ll teach me to use a lead from the battery next time to my test bulb.

If anyone is a bit worried about taking their airbag out to fix this - as long as u follow the procedure for disarming it - it`s prolly the easiest job I`ve ever done on a car. 2 torx screws, bag off, horn connector back in and put it all back in 10 mins.

Just one last question though. Does anybody know what this connector is - and if it should have a relay in it - or is it redundant?

It`s under the steering colum - well just to the right of it. - 1 of two relay connectors. There are 3 more relay connectors on the left of the column - but these two are on the right. The larger wire is orange irl not red.



Cheers,

Dom

Ray Quayle

Good job getting it sorted Dom. I've never been to the Leeds meet. I occasionally get the the CCCUK Yorkshire Region meet though. Do you ever go to the CCCUK Corvette Nationals?

DWC4

Horn on '92 - the ADLS Code procedure shows and running power direct to them both shows my built in horns are bad but a test horn wired to the horn lead up front honks when I run the codes test (section 1.4 test 14), but won't honk the test horn using steering wheel buttons so, it's something in the steering wheel and I need to pull it, righ? thanks!

stoydido

if it's like 91 with thumbs you pull air bag to get to contacts. easy. torx 27 bolts, that come loose, not all way out of steering wheel.

yes, sounds like it is in the thumbs, button, whichever.

DWC4

THANKS, will do.

stoydido

left out this: pull air bag fuse. when bag is loose, let it hang by yellow wires, maybe tape it in place.

BUT...if you think the button contacts are loose, whatever, gently pry the thumbs out with a puttly knife, move button to one side then rotate it out. that gets to the contacts. they may have slipped out of their bay, picture frame.

on mine, 91, I had to remove air bag, then secure the grounding wire. can send you the details of what I did -won't be in the fsm, but works- if you want.

jc

DWC4

Hey thanks, I like the idea of checking behind those thumbs before I pull the wheel a LOT, good chance the problem is in there. So they'll just pop out if I pry gently/evenly on my 92. . I'll see if FSM shows that for mine, hate to damage it but doubt they changed something like that from 91 to 92. THANKS much for the followup and tips!