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Discussion Starter #1 (Edited)
Horn issue - RESOLVED! (see pg 2)

Hey guys,

So I bought the car last summer and have a few things to fix on her.. first off is the horn which is all I need to get it inspected/insured/on the road. Horn is not working, (not stuck on or intermittent like many others have had).

I have also pulled up the service manuals to look at horn specs and wiring diagrams, but not sure what else I can get from them.. unless it has something to do with the alarm (but the rest of the alarm functions fine).

Anyway I have searched the forum and tried a bunch of things... Any help would be greatly appreciated! Maybe I'm missing something obvious, but here is where I'm at:

1-Horns themselves work fine (disconnected from the car and hooked directly to 12V)

2-Cruise and Hazards work (well I have some issues with cruise but it powers up, so I don't think is a clockspring problem)

3-Alarm works (minus the horn) when I lock the doors, then reach through window and open the door. Headlights pop up and hazards blink

4-swapped fuse and relay with working ones. (relay worked for the fog lights for example)

5-pulled off the airbag and tested the horn buttons and continuity between the 2 buttons and where they connect into the clockspring. All good connections there

6-have continuity from the battery (pos) to the relay, and to the fuse.

7-Don't have continuity between the relay connector (bottom half) and the horn wires (end where the horn connects). Shouldn't there be? /does this mean that connector itself is bad? (it looks fine/no corrosion etc and seems unlikely to just break?)

Really looking forward to getting this fixed/inspected/back on the road!
Thanks for any help!
 

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The alarm horn is completely separate from the main horns and is located under the throttle cable box next to the driver side engine mount.

The main horns are located in the front center grill (assuming someone hasnt moved them). The wiring for them is extremely simple. Assuming you have power at pins 1 & 5 of the horn relay, try pulling the relay and jumping pin 5 to pin 4 and then checking for voltage at the horns. If you do, test for continuity to ground on the other (black) wires.
 

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Discussion Starter #3
Thanks for the reply striker.
I know where the horns are located (removed them and tested them separately, as well as the alarm horn (though I didn't remove that one to test yet come to think of it). I have not tried jumping the pins yet, so I can definitely try that next.

Wouldn't the issue have to be somewhere else though considering that both the normal horns AND the alarm horn aren't working? (didn't think the alarm horn goes through the same relay). or are they both going through that relay connector?
 

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Thanks for the reply striker.
I know where the horns are located (removed them and tested them separately, as well as the alarm horn (though I didn't remove that one to test yet come to think of it). I have not tried jumping the pins yet, so I can definitely try that next.
Lots of people arent aware that there is a separate alarm horn and it wasnt totally clear that you were so I figured it was worth noting just in case.

Wouldn't the issue have to be somewhere else though considering that both the normal horns AND the alarm horn aren't working? (didn't think the alarm horn goes through the same relay). or are they both going through that relay connector?
They do have different relays, however the only thing they have in common on the power side is fusible link 6 (large 40A in the under-hood junction box) which provides power for several other things so you would have more than horn issues if that were bad. On the trigger side, both relays can be triggered by the ETACS system but that wouldn't keep the horn switches in the steering wheel from working.

All the horns ground in the fender wells (main horns in the passenger side and alarm horn in the driver side) which can sometimes get pretty corroded so it may be a grounding issue.
 

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Discussion Starter #5 (Edited)
I thought about the ETACS, and I recently got BlackStealth's ScanTool (which is awesome) so thought that may help, but it only shows pulses, no codes or wave forms for that system.

I did not know where the grounds were, not easy to trace wires in this engine bay >:S ... so thanks! (are they easy to get to? I'll try that tomorrow). Seems weird for 2 separate spots to be bad.. but I guess if it's a common area for corrosion it could be the case. Will try and give an update here, Cheers!

edit: found the diagram in the service manual (showing grounding locations) so I should be able to find it with that
 

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5-pulled off the airbag and tested the horn buttons and continuity between the 2 buttons and where they connect into the clockspring. All good connections there
But did you check for continuity to ground from clockspring connector when horn buttons where pushed.

7-Don't have continuity between the relay connector (bottom half) and the horn wires (end where the horn connects). Shouldn't there be? /does this mean that connector itself is bad? (it looks fine/no corrosion etc and seems unlikely to just break?)
Don't completely understand your question here. If "(bottom half)" means relay plug socket, there should be two large and two smaller plug points in socket. With relay removed, one large and one small should have 12volts on them, the other smaller socket (without voltage) should have continuity to ground only when horn button is pressed.
 

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Discussion Starter #7 (Edited)
But did you check for continuity to ground from clockspring connector when horn buttons where pushed.
hmm I'll have to double check this.. but the buttons were clean/contacting well, and isn't the main steering wheel (metal part inside) a ground? I guess I'll have to confirm that's working by touching to another ground somewhere eh.

Don't completely understand your question here. If "(bottom half)" means relay plug socket, there should be two large and two smaller plug points in socket. With relay removed, one large and one small should have 12volts on them, the other smaller socket (without voltage) should have continuity to ground only when horn button is pressed.
Yes by "bottom half" I meant the socket, sorry. I did confirm 12V on those parts, but did not check for continuity to ground (with button pushed), so that at least gives me another thing to test.

Thanks for the help so far guys, I'm hopeful that between checking the grounds in the fenders and these last 2 tips I'll get a better answer tonight when I get home!
 

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hmm I'll have to double check this.. but the buttons were clean/contacting well, and isn't the main steering wheel (metal part inside) a ground? I guess I'll have to confirm that's working by touching to another ground somewhere eh.
Yes that would be the ground point for steering wheel horn buttons. Basically buttons just grounds control side of relay causing it to close, which then passes power from larger 12v socket plug point thru relay to other larger socket plug point and on to horns causing them to blow.

If you check smaller plug socket (one without power) to ground and it shows continuity when horn button pushed, steering wheel buttons are working correctly and no need to check in steering wheel.

Yes by "bottom half" I meant the socket, sorry. I did confirm 12V on those parts, but did not check for continuity to ground (with button pushed), so that at least gives me another thing to test.
OK… then your #7 question in first post sounds like you’re questioning if larger socket plug point (without power), should have continuity to horn connectors. If so answer is YES, there should be continuity from there to both horn connectors on the Green wire with red stripe. That’s the only way power can get to horns when relay closes.


Edit: Just for clarity we’re talking about horn relay in junction box under hood between engine air filter and head light, NOT horn relay at fuse box inside of car which is for alarm horn.
 

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Discussion Starter #9
I finally got a chance to go check this sorry for the delay on follow up (busy weekend!) Really aiming to get this figured out before the end of the week/next couple of days now.

Yes that would be the ground point for steering wheel horn buttons. Basically buttons just grounds control side of relay causing it to close, which then passes power from larger 12v socket plug point thru relay to other larger socket plug point and on to horns causing them to blow.

If you check smaller plug socket (one without power) to ground and it shows continuity when horn button pushed, steering wheel buttons are working correctly and no need to check in steering wheel.
I did get continuity when checking between smaller plug socket (one without power) to ground when the horn button was pushed.. but it still had continuity WITHOUT the button pushed too... I thought that would mean the horn would be stuck on... (which is not the problem so not sure what I'm missing here!). Is something cross wired or what else could it be?

So to be clear, this is what I got: Good continuity between one large socket plug and the horn black wires, and also good continuity between one small socket plug and the horn black wires. Makes no difference if the horn buttons are pushed or not. :confused:
 

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Discussion Starter #10
*UPDATE*

Ok, so I've narrowed down some more things and think it's down to a spotty ground connection from the steering wheel..? Looks like I'm not getting solid/constant continuity from the metal part of the wheel to a known ground. Where would be the weak point of this be?.. should I pull the dash under the steering wheel out to chase a ground wire or is there an obvious point?

Basically how I came to this:
Grounds in the wheel fenders were pretty corroded so that was a spotty connection.. cleaned up, still doesn't work. Tested wiring from relay to horns and all seem good. Horn works when I jump the relay socket, so I've now narrowed it to the control side (ie somewhere between the steering wheel button and the relay). Buttons work well and good continuity/contact from the buttons to the metal steering wheel.
 

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Basically how I came to this:
Grounds in the wheel fenders were pretty corroded so that was a spotty connection.. cleaned up, still doesn't work. Tested wiring from relay to horns and all seem good. Horn works when I jump the relay socket, so I've now narrowed it to the control side (ie somewhere between the steering wheel button and the relay). Buttons work well and good continuity/contact from the buttons to the metal steering wheel.
There’s a plug C-57 under dash near steering column (4 pin straight plug). It should have Green wire with black stripe on one side of connector and Gray wire on the other side of pin #2 which goes to clock spring. Try grounding that connector pin with short jumper wire and see if horn blows.

If it doesn’t blow when grounding pin2, that would indicate problem is between that plug and relay ground control socket.

If it blows problem is in clock spring assembly or poor ground with buttons thru column shaft. To test unplug that connector and take continuity reading between Gray wire at open plug to same wire going to buttons under air bag. Basically trying to eliminate clock spring as the problem
 

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Discussion Starter #13
Ok, I've removed the knee protector, followed the wire from the horn buttons (mine is a green/red wire) to the plug (C-57 I believe). Unplugged and grounded Pin#2 (green/black wire) with a jumper to a known ground.

No horn sound. (12V confirmed at the battery, and as said before the horns and relay all tested good).

So if I've tested this correctly, my issue is between plug C-57 and the relay correct? (good because that rules out the clock spring area, but bad because that seems like a pain in the @$$ to trace from there:S... I've attached pictures here to show what I was looking at/testing.
 

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....So if I've tested this correctly, my issue is between plug C-57 and the relay correct?........
Yeah, that's what that indicates (you did have relay in place, Right?). Prints show that Green/black wire running back to relay plug for grounding control side to close it and blow horn. It does pass thru C-02 connector (large 19 pin) somewhere near or above fuse box.

I can't recognize C-57 by sight, just have to go by schematics. If your wire from C-57 plug to clock spring/buttons is Green/red, that indicates another error with prints, not the first found by the way. That wire is shown as "GR" which indicates Gray wire by legend. Green wire with red tracer should be "G-R", only difference is the "-" an easy mistake and is what got me a little confused at first causing edits.
 

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Discussion Starter #16
hmm. Yep relay was in and 12V was all connected. And yep definitely Green/red wire going from C-57 plug to horn buttons. I'm at work right now (with a few min to spare) so trying to wrap my head around things before I get back at it

I'm attaching the wiring diagram in this post to keep things clear.

According to what I've tested and what I see on the diagram, this only leaves the wires between the relay and C-57 (which includes one other connector C-02) to test right?

Unless there is something to check that goes in between the theft alarm horn and the regular horn.. On the wiring diagram it makes think there could be especially since the alarm horn also isn't working... but not sure I understand that part of the diagram since there is no connector between C-57 and C-02. Thoughts?
 

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.....
According to what I've tested and what I see on the diagram, this only leaves the wires between the relay and C-57 (which includes one other connector C-02) to test right?......
That’s correct, also could be break in Green/black wire between C-02 and relay socket or even bad connection at relay socket itself.

Unless there is something to check that goes in between the theft alarm horn and the regular horn.. On the wiring diagram it makes think there could be especially since the alarm horn also isn't working... but not sure I understand that part of the diagram since there is no connector between C-57 and C-02. Thoughts?
Horn circuit with alarm.png Another problem found in many of theses prints is incomplete lines, requiring some interpretation. The junction of lines circled in red should look same as where circled in yellow. That line allows ETACS to ground and blow regular horns at same time it does alarm horn, while the diode in that line doesn’t allow any current flow to other leg between C-02 & C-57 keeping horn buttons from blowing alarm horn. At first impression you would wonder why have an alarm horn if regular horns are also used, I suspect it’s a backup feature so some horn will work during alarm with either dedicated fuse #3 or multi-purpose fuse #14 blown or failure of either relay (Probably more than you wanted to know :) ). But I can’t imagine any problem on alarm side keeping regular horn side from working.

Edit: An after thought, C-02 connector not plugged together properly could disable both sides as wire from both are shown passing thru that connector (indicated by dashed line). Also that dashed line shows connections at pin 7 & 18, looking at plug layout at bottom of page shows those two pins are above/below each other (coincident maybe :confused: ).
 

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Discussion Starter #18 (Edited)
thanks for this info, and appreciate your input! definitely helps decipher the diagram (I realize it's explained at the beginning of the document but still, these take awhile to realize what you're looking at!).
Not really understanding the diode in the diagram though.. looks like it's allowing power right to left and blocking left to right, but what does that accomplish? allows ETACS to power all horns?

Anyway, I'm going to try ground pin 7 and 18 within C-02 and see if that makes the horns blow.. hopefully it does, then it's just a short wire to replace that I have access to at this point. ..I think.. lol
 

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.....Not really understanding the diode in the diagram though.. looks like it's allowing power right to left and blocking left to right, but what does that accomplish? allows ETACS to power all horns?.....
That is correct about direction of flow and no flow, which does allow regular horn relay coil (control) to be energized closing that relay so those horns will blow along with alarm horn, which is energize by the Blue/green wire (L-G) so as you said blows all horns. While not allowing steering wheel buttons to cause flow left to right keeping relay coil for alarm horn from being energized and keeping alarm horn from blowing when steering wheel buttons pushed.

Edit: If above is confusing… simply put, diode does allow ETACS to power all horns and Steering wheel buttons to only blow regular horns.

Anyway, I'm going to try ground pin 7 and 18 within C-02 and see if that makes the horns blow.. hopefully it does, then it's just a short wire to replace that I have access to at this point. ..I think.. lol
Grounding pin 7 should cause regular horns to blow. But grounding pin 18 won’t do anything, because if you look at diagram closely pin 18 is on power delivery side of relay for alarm horn not the control side ground for the relay.
 

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Discussion Starter #20 (Edited)
FIXED! :D

I got to the point of narrowing it down to a bad wire between the relay (engine compartment) and the first plug/connection the wire goes through (C-02 as shown in wiring diagram). Essentially decided I had to run a new wire because the wire joins the harness/clump of hundreds of other wires going in the engine bay... so definitely not worth ripping that apart at risk of damaging another wire(s).
I forgot to take pictures of where I ran the new wire, but I stuck one end in the bottom of the relay socket (where the current non-functioning ground wire is), ran around the back of the engine then through the firewall (used the grommet on the driver's side as shown in the Stealth316 link below), then joined it into plug C-57 pin #2 as in the pictured above.

Then just put everything back together and voila! Horn finally works as it should using the normal buttons on the wheel:)
What a massive pain in the A$$ that turned out to be... but was necessary for getting the car certified, and well, I learned some about our electrical wiring diagrams and a few other annoying things along the way lol. Hopefully someone else can skim through this thread and get something from it if they have a horn issue down the road!

Thanks a lot to white93gt, striker3, and Stealth 316 for plenty of help/info. Cheers!

http://www.stealth316.com/2-dashpanelaccess.htm
 
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