Cadillac Toots Its Own Horn

“Hey neighbor, was that your Caddy’s horn I heard blasting at three 3 a.m.?” I asked, peering over the fence through sleep deprived eyes. “Yeah sorry,” he said. “Its been doing that a lot lately, and its really intermittent. But if I smack the steering wheel, it quits for a while. Do you know someone that can fix it?” “Sure,” I replied. “I can.”

Although my shop specializes in Import vehicles, I have ALLDATA Online, which gives me access to diagnostic and repair information for Domestic vehicles as well as Imports. I’m sure I’ll be able fix that for you.” We set an appointment for early the next morning.

I didn’t have to see him coming. Even though I was inside the shop, I could hear his horn honking sporadically from four blocks away. As he pulled into the service drive, he silenced it with one quick jab to the horn button. Before it could go off again, we quickly checked the technical service bulletins for his particular vehicle, a 1993 Cadillac Eldorado. There was one that matched his symptoms exactly.

According to the bulletin, the vehicles involved were some 1989 to 1993 Cadillac DeVille and Fleetwood (FWD), and all the 1990 to 1993 Eldorado, Seville and Allante models equipped with a Supplemental Inflatable Restraint (SIR). The bulletin stated that these vehicles could experience a condition where the horn chirps intermittently or sounds continuously. To repair this problem, the following procedure should be followed exactly:

1. Disable the SIR system.

2. Disable the horn by removing the horn relay.

3. Remove the SIR inflator module from the steering wheel.

4. Remove the steering wheel.

5. Place the steering wheel on a solid work surface that is covered with a soft cloth. Rest it on the rim, with the back facing up. (Refer to Figure 1.)

6. Tap out the two spiral tap fasteners, which retain the horn contact assembly to the steering wheel, using an appropriately sized hardened punch and hammer. (Refer to Figure 1.)

7. Turn the steering wheel over so that it rests on its backside with the rim facing up.

8. Replace the horn contact assembly with a new type horn contact assembly. (Refer to the Part Number Application Chart.)

NOTE: Do not substitute any component parts from one horn contact assembly to another. Proper operation of the horn contact assembly requires that it be replaced as a complete assembly.

9. Align the new horn contact assembly to the steering wheel.

10. Hand start two new spiral tap fasteners and gently tap with a hammer to set them. DO NOT attempt to drive the fasteners fully at this time.

11. Fully seat the two fasteners using an arbor press, if available, making certain the fasteners are driven straight and fully seated. The horn contact assembly should be tight against the center hub of the steering wheel.

NOTE: If an arbor press is used to seat the fasteners, continue with step 16. If an arbor press is not available, continue with step 12.

12. Place the steering wheel with its backside down on top of a large socket so that the socket rim supports the metal insert of the steering wheel as close to the fastener holes as possible.

13. Have another technician stabilize the steering wheel on top of the socket by supporting the rim with two hands.

14. Drive the two spiral tap fasteners with a hammer and hardened punch large enough to cover the spiral tap fastener head.

15. Ensure that the fasteners are driven straight and fully seated. The horn contact assembly should be tight against the center hub of the steering wheel.

After mounting the updated horn contact as described in the bulletin, I installed the steering wheel, SIR inflator module, enabled the SIR system and parked the car outside; where it sat five hours without a making so much as a beep. My neighbor was really impressed with how efficiently I was able to diagnose and repair his car. I was happy to finally get a full night’s sleep.