'97 horn blows constantly

In the '95, you pull the IP/1 fuse in the rear fuse panel. If you do that in the '97 you lose the tach and heater as well. My '97 manuals are in the mail so I hope the answer will be in them. The problem is the security system which is activating the horn relay. This '97 is brand new to me and came with just a few problems, this being one. Both horns were shot and the 20 amp horn fuse was blown. My replacement horns came today and the left side (the first one getting attention) started to blow as soon as I connected it. I then pulled the relay and fuse and began to do the right side. I'll keep checking. I REALLY want to disable the entire security system permanently. I do not live in or visit cities. The manuals will NOT tell me how to do more than the single fuse (which just might have more than one function like the '95), so, some genius here has probably figured out how to disable the entire system and will kindly tell that to me. Thanking you ahead of that,....

Is the horn pulsing or blowing? If simply blowing, the problem may actually be the contact pad under the airbag cover. Just saying.

A friend is going to get me the security screw bit that I need to remove the airbag/horn button today. HE thinks that it is the horn button as well. BUT my interior lights go on and stay on even after I drive away for many minutes. Can't find that in the owner's book either. When I got to the right side horn yesterday I realized that the left side one had already been replaced (aftermarket type instead of original) and it had burned out again.STILL want to disable the security system. I did so in my '91 Mercedes after the 3rd time IT went a-horn blowing without any provocation. That was easy, only disconnecting the module under the right-side footrest.

"BUT my interior lights go on and stay on even after I drive away for many minutes. "

Short answer: Unrelated Problem.

Longer answer: That's likely a defective microswitch in one or another door latch, or a short in the wiring - typically where the wire bundle passes from drivers door jamb into the door itself, on the A pillar. I don't know how to replace that microswitch; typically one simply replaces the latch mechanism. They may still be available from GM dealers. If not - junkyard.

"STILL want to disable the security system. I did so in my '91 Mercedes after the 3rd time IT went a-horn blowing without any provocation. That was easy, only disconnecting the module under the right-side footrest."

Short answer: This isn't a Mercedes (although the Riv's Bosch fuel injection is like that on one or another Merc and I think an Audi), and you're making good progress.

Better answer: If your security system is working 100% then it is easier to diagnose a no-start; I would repair things and not disable it. Key reason is that if you bypass it, you can have a no-start that is attributable to the security system but not be able to diagnose it as easily because you've disabled the audible part. Some security no-starts are silent, some trigger the pulsing horn. None trigger a steady horn.

"Can't find that in the owner's book either."

Short and only answer: if you don't have one already, get a factory service manual set (pronto).

Oh, I ordered the '97 set as soon as I realized that my '95 set (for my other 2 Rivieras) had differences. Hmmmm. eBay says that it was delivered TODAY and so "was" a rather large item. Something is funny but I'm not laughing.I'll get back to you. Thanks for the long answers.
OK, they WERE delivered, just to the wrong part of the property. Substitute mailman. There IS a test for courtesy lights staying on too long but is very confusing. It's OK for the first page but then goes all Oldsmobile Aurora on the 2nd, asking to open and close rear doors. It also indicated that I have to remove door panels to get at latch switches. I ALSO have to use the remote which I HAVE on order but did not come with this Riv. The one I have from the Platinum Beige Metallic obviously won't do the job. This company sending the (two) fobs tells me that their procedure can program the fobs to my new ride. Hope so. AN-other confusing part, right at the beginning, talks about the number of chimes you hear when it enters the diagnostic mode (after holding down lock button and cycling the headlights 6 times then releasing lock button, reveals some past history but does not tell me where to FIND the information. I'll keep this up to date after I get my new fobs.

I removed the steering wheel hub - carefully- and measured the resistance of each of the 2 horn "buttons". Complete open until touched then 1.6 ohms when pushed. So, clearly not a horn button issue. BTW, my OBD2 connector is NOT like what is in the book. I have contacts at 1, 3, 6 and 8, upper row. Number 4 (not there) is simply ground, so, I can program my new fobs (different issue not posted about).

JohnBoanerges wrote:

I removed the steering wheel hub - carefully- and measured the resistance of each of the 2 horn "buttons". Complete open until touched then 1.6 ohms when pushed. So, clearly not a horn button issue. BTW, my OBD2 connector is NOT like what is in the book. I have contacts at 1, 3, 6 and 8, upper row. Number 4 (not there) is simply ground, so, I can program my new fobs (different issue not posted about).

Down to a certain serial number, the Riv was OBD1 wired into an OBD2 connector.

If the horn is steady and not pulsed, consider checking the wiring from/thru the steering column. Look for splices under the dash, as well as chafing on the insulation on the wires under the clamshell. When my steering column tilt mechanism was repaired I had to go back in to affix the wiring, the tech didn't reroute the wires correctly. Eventually they would have chafed against metal parts and done all sorts of silliness. You may need a small hex/torx socket to get the bolts out of the clamshell - use a flashlight & look up in the holes, it'll be obvious.

Which reminds me, if that steering hub cover was misinstalled (removed/reinstalled for some reason) it could pinch the horn pad(s) and they'd work ok when out but be continuous when installed.

Today I fixed my horn blowing problem. The issue was never a fault in the pad switches. I tore 2 horn button/ su[supplemental restraint systems apart, the 1st from my donor green '95. I buzzed off the 8 rivits holding all together then pulled the remains out througth the bottom of the steel plate. I then tapped the holes M4. These pads tested perfect and the ones in my new red '97 were suspect. Next I removed the assembly from the '97 and broke it down and tested the pads. Perfect again. Putting it BACK together it just kept blowing the horn. Then I did the switch and installed THAT. It blew the horns. Back apart and adjusted the side switches in case they were exerting pressure to cause the horn to blow and re-installed. Still blowing. My final and successful solution was to cut from the inside of the cover about 1 mm of plastic that contacts the pad switch, just the raised "X" parts. I figure that as the plastic ages, it contracts and gives the fatal pressure to the pad switches. Mine is now all good. This solution should make the record books. When I got my Platinum Beige Metallic '95, the horn switch was a red button screwed to my dash. I will now take a look at that in case I can solve it for that car as well

Regarding the OBD 1 vs OBD 2 issue, I will check after dinner. The figure in the '95 set of books is upside down to the figure in the '97 book and that may be throwing me off. All I care about next is programming my new fobs and I only need 8 and body ground to do that.

JohnBoanerges wrote:

Regarding the OBD 1 vs OBD 2 issue, I will check after dinner. The figure in the '95 set of books is upside down to the figure in the '97 book and that may be throwing me off. All I care about next is programming my new fobs and I only need 8 and body ground to do that.

You're making great progress.  That horn short, that had to be really a pain. Yes this is one for the FAQ/Write-ups.

And thanks again for your continued help. It does inspire.

Yep, I re-looked from an upside down perspective and I DO have the pins that the book states.