GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

Important: Use the J 35616 whenever a diagnostic procedure requires you to test or probe a terminal. Use the J 35616 for the following reasons:

   • In order to prevent damage to the terminal
   • In order to indicate whether the contact tension is sufficient
If the contact tension seems incorrect, refer to Checking Terminal Contact in Troubleshooting Procedures.

1

Test the vehicle for UA6 theft deterrent option.

Is the vehicle equipped with UA6 system?

--

Go to Step 2

Go to Step 3

2

Test the vehicle for body control module DTCs.

Refer to Diagnostic System Check - Body Control System in Body Control Systems.

Are any DTCs present?

--

Go to the appropriate DTC table in Body Control Systems

Go to Step 3

3

  1. Remove the horn relay.
  2. Connect a test lamp between horn relay terminal 86 and ground.

Does the test lamp light?

--

Go to Step 4

Go to Step 5

4

Connect a test lamp between horn relay terminal 30 and ground.

Does the test lamp light?

--

Go to Step 6

Go to Step 5

5

  1. Test for a poor connection at the underhood accessory wiring junction block.
  2. Test for a poor connection at horn relay terminals 86/30.
  3. If the connection is OK, replace the underhood accessory wiring junction block. Relay/Fuse Center Replacement

Is the symptom still present?

--

System OK

--

6

  1. Connect a test lamp between horn relay terminal 86 and terminal 85.
  2. Press the horn switch while observing the test lamp.

Does the test lamp light?

--

Go to Step 10

Go to Step 7

7

  1. Remove the horn switch(es) from the steering wheel.
  2. Ensure that the test lamp is still connected between horn relay terminal 86 and terminal 85.
  3. Connect a fused jumper (5A) from the ground to the spring loaded terminal leading toward the underhood accessory wiring junction block.

Does the test lamp light?

--

Go to Step 9

Go to Step 8

8

Repair a short to B+ power or an open in CKT 28.

Is the symptom still present?

--

System OK

--

9

  1. Inspect the ground wire connections for the horn switches in the steering wheel.
  2. If all of the connections are OK, replace the horn switches.
  3. • For Chevrolet refer to Steering Wheel Replacement in Steering Wheel and Column - Tilt.
    • For Pontiac the horn switches are not serviceable. Inspect the horn lead for an open or bad connections, also inspect the inflator module to steering wheel contacts for a bad connection, refer to Inflatable Restraint Steering Wheel Module Replacement in SIR

Is the symptom still present?

--

System OK

--

10

Momentarily connect a fused jumper (5A) between horn relay terminal 30 and terminal 87.

Do the horns sound?

--

Go to Step 11

Go to Step 12

11

Replace the horn relay, in Underhood Accessory Wiring Junction Block.

Is the symptom still present?

--

System OK

--

12

  1. Remove the left and right horn connectors.
  2. Connect a fused jumper (5A) from the ground to terminal A at the left horn or the right horn.
  3. Connect a fused jumper (5A) from B+ power to terminal B at the left horn or the right horn.

Do the horns sound?

--

Go to Step 14

Go to Step 13

13

Replace the inoperative horns. Horn Replacement

Is the symptom still present?

--

System OK

--

14

Using a J 39200 , test for continuity to ground in the following circuits:

    • CKT 1250
    • CKT 1350

Do CKT 1250 and CKT 1350 show continuity to ground?

--

Go to Step 16

Go to Step 15

15

Repair CKT 1250 or CKT 1350 for an open to G102 or G101.

Is the repair complete?

--

System OK

--

16

Repair an open in CKT 29, between the underhood accessory wiring junction block and the inoperative horn(s).

Is the repair complete?

--

System OK

--