GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 1999 🢒 Grand Prix 🢒 Body and Accessories 🢒 Horns 🢒 Horns Always On

Step

Action

Value(s)

Yes

No

Important: Use the J 35616 Connector Test Adapter Kit when a diagnostic procedure requires inspecting or probing.

Use of the adapter prevents damage to the terminal. Use of the adapter also indicates if the contact tension is sufficient. If the contact tension seems incorrect, refer to Checking Terminal Contact.

1

Inspect the vehicle for the UA6 theft deterrent option.

Is the vehicle equipped with the UA6 theft deterrent option?

--

Go to Step 2

Go to Step 3

2

Inspect the vehicle for body control module (BCM) diagnostic trouble codes (DTCs). Refer to Diagnostic System Check - Body Control System in Body Control System for more information.

Are there any DTCs present?

--

Go to Diagnostic System Check - Body Control System in Body Control Systems

Go to Step 3

3

Remove the horn relay.

Do the horns stop sounding?

--

Go to Step 4

Go to Step 13

4
  1. Connect a test lamp.
  2. Frontprobe between the horn relay terminals CKT 740 and CKT 28. Refer to Fuse Block Details in Electrical Diagnosis for terminal location.

Does the test lamp illuminate?

--

Go to Step 5

Go to Step 7

5
  1. Place the test lamp in the same location.
  2. Disconnect the BCM connector C2.

Does the test lamp illuminate?

--

Go to Step 6

Go to Step 8

6
  1. Disconnect connector C201.
  2. Connect a test lamp.
  3. Frontprobe between the horn relay terminals CKT 740 and CKT 28.

Does the test lamp illuminate?

--

Go to Step 9

Go to Step 10

7

Replace the horn relay. Refer to Horn Relay Replacement for service procedure.

Is the repair complete?

--

Go to Diagnostic System Check - Horns

System OK

8

Replace the BCM. Refer to Body Control Module Replacement in Body Control System for service procedure.

Is the repair complete?

--

Go to Diagnostic System Check - Horns

System OK

9

Repair the short to ground in CKT 28 between the BCM and the accessory wiring junction block or between the accessory wiring junction block and C201.

Is the repair complete?

--

Go to Diagnostic System Check - Horns

System OK

10
  1. Disable the supplemental inflatable restraint (SIR) system. Refer to Disabling the SIR System and Enabling the SIR System in SIR for service procedure.
  2. Remove the horn switch from the steering wheel.
  3. Disconnect the spring loaded terminal of the horn switch leading to connector C201. Leave the switch ground connected.
  4. Connect a test lamp.
  5. Probe between B+ and the spring loaded terminal that leads toward the horn switch.

Does the test lamp illuminate?

--

Go to Step 11

Go to Step 12

11

Replace the horn switch. Refer to Horn Replacement for service procedure.

Is the repair complete?

--

Go to Diagnostic System Check - Horns

System OK

12

Repair the short to ground in CKT 28 between the horn switch and C201.

Is the repair complete?

--

Go to Diagnostic System Check - Horns

System OK

13

Disconnect the accessory wiring junction block connector C3.

Do the horns stop sounding?

--

Go to Step 14

Go to Step 15

14

Replace the accessory wiring junction block. Refer to Accessory Wiring Junction Block Replacement in Body Front End for service procedure.

Is the repair complete

--

Go to Diagnostic System Check - Horns

System OK

15

Repair the short to B+ CKT 29 between the horn connector and the accessory wiring junction block.

Is the repair complete?

--

Go to Diagnostic System Check - Horns

System OK