EI07279 - Horn Inoperative from Steering Wheel Horn Pad (Engineering Information)

Important:  If the horn does not work from the key fob horn button, disregard this bulletin and proceed with diagnosis/repair according to SI.

Some customers may comment that the horn is inoperative from the horn pad on the steering wheel.

GM Engineering is attempting to find the source of an open in the ground path through the steering column.

GM has a need to obtain information DURING diagnosis. If the customer's concern can be duplicated, perform the following inspection/steps:

1. Does the horn work by depressing the button(s) on the key fob?

•	Yes -- proceed with step 2.

•	No -- do not proceed with this bulletin - diagnose and repair using information found in SI.

Caution :  When performing service on or near the SIR components or the SIR wiring, the SIR system must be disabled. Refer to SIR Disabling and Enabling . Failure to observe the correct procedure could cause deployment of the SIR components, personal injury, or unnecessary SIR system repairs.

2. Remove the Inflatable Restraint Steering Wheel Module using the procedure found in Service Information.
3. Remove the left side IP insulator (refer to Instrument Panel Insulator Panel Replacement found in SI) so it can be moved aside enough to see the steering column.
4. Depress the horn contacts in the steering wheel. Does the horn work?

•	Yes -- proceed to step 8.

•	No -- proceed to step 5.




5. Inspect the steering column through the insulator panel location. Note: The shaft from the steering wheel comes through a metal bracket. That bracket is surrounded by plastic, which is inside of another metal bracket. Look for a small metal clip (refer to graphic above) that connects the inner bracket (inside the plastic) and the outer bracket. Is the clip present?

•	Yes -- proceed to step 6.

•	No -- note the missing clip on the repair order. Proceed to step 8.

6. Without touching the clip, use a test light or ammeter to jumper between the red wires on the horn contact and the outer bracket on the steering column. Does the horn work when the jumper touches the outer bracket? Remove the small clip and inspect for signs of corrosion and note findings on the repair order. Clean off any corrosion and reinstall the clip. Does the horn work when the horn contact is depressed?

•	Yes -- note on the repair order and proceed to step 8.

•	No -- proceed to step 7.

7. Jumper between other grounded points and the red horn wire. Does the horn work when jumpered to another ground?

•	Yes -- note which ground enabled the horn to work. Proceed with step 8.

•	No -- refer to "Horn Inoperative" section in SI to diagnose which component in the circuit is causing the horn inop. Note on the repair order and make the necessary repairs. Proceed to step 9.

8. Complete the following steps to add a ground strap between the mounting bolts of the steering column.




8.1.	Refer to item number 2 in the graphic. This graphic shows the column support assembly. A closer look will reveal the four mounting holes of the column support assembly.

Important:     •  If a grounding strap cannot be obtained locally, one can be made by obtaining two eyelets that match the size of the column support bolts or studs and a 12 gauge (3.0 mm) wire. Cut the wire to the length needed in order to complete the circuit.    •  Some model year vehicles switched to column bracket and/or mount that may be isolated by rubber. It may be necessary to locate an alternate location to secure the ground wire to the column or column bracket in order to complete the circuit.

8.2.	Add one (1) grounding strap from the column mount (use only one of the two upper mounting holes) to one of the two lower mounting holes in the steering column support assembly.

8.3.	Proceed with step 9.

9. Contact the engineer -- Dave Orth (248-676-1878) to provide diagnostic results. If the engineer is not available to take the call, fax the front and back of the completed repair order to:

-	Attention: Dave Orth

-	Fax #: 248-685-6140

For vehicles repaired under Engineering direction, use: