GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Inspect the HORN/DM fuse.

Is the fuse open?

--

Go to Step 2

Go to Step 3

2

Locate and repair the source of the overload in CKT 40 (ORN) and replace the fuse.

Is the repair complete?

--

System OK

--

3

Inspect the condition of G 200 (P42), or G 200 and G 102 (P32).

Are the grounds clean and tight?

--

Go to Step 5

Go to Step 4

4

Repair G 200 or G 102 as necessary.

Is the repair complete?

--

System OK

--

5

Are both horns inoperative?

--

Go to Step 7

Go to Step 6

6

  1. Disconnect the inoperative horn connector.
  2. Connect a test light from the horn connector cavity B to ground.
  3. Press the horn button.

Did the test light illuminate?

--

Go to Step 9

Go to Step 8

7

  1. Remove the horn relay.
  2. Connect a test light from the horn relay connector cavity 85 to ground and cavity 87 to ground.

Did the test light illuminate?

--

Go to Step 12

Go to Step 10

8

Locate and repair open in CKT 29 (DK GRN) between the horn connector, cavity B and the horn relay connector.

Is the repair complete?

--

System OK

--

9

Connect a test light from the horn connector cavity A to B +.

Did the test light illuminate?

--

Go to Step 20

Go to Step 11

10

Locate and repair the open in CKT 40 (ORN) between the HORN/DM fuse and the horn relay connector.

Is the repair complete?

--

System OK

--

11

Locate and repair the open in CKT 150 (BLK) between the horn connector cavity A and G 200 (P42), or G 102 (P32).

Is the repair complete?

--

System OK

--

12

  1. Connect a test light from the horn relay connector, cavity 86 to B +.
  2. Press the horn button.

Did the test light illuminate?

--

Go to Step 13

Go to Step 14

13

  1. Disconnect either inoperative horn connector.
  2. Connect a fused jumper wire between the horn relay connector cavity 87 and cavity 30.
  3. Refer to Using Fused Jumper Wires in Wiring Systems.

  4. Connect a test light from the horn connector cavity B to ground.

Did the test light illuminate?

--

Go to Step 19

Go to Step 16

14

  1. Disconnect the turn signal switch connector at the base of the steering column.
  2. Use a J 39200 DMM to measure the resistance between the horn relay connector cavity 86 and cavity G of the disconnected wire harness.

Is the resistance greater than the specified value?

1.0ohms

Go to Step 17

Go to Step 15

15

Use a J 39200 DMM to measure resistance from the turn signal switch connector cavity G (steering column side), to ground while pressing the horn button.

Is the resistance greater than the specified value?

5.0ohms

Go to Step 18

Go to Step 13

16

Locate and repair the open in CKT 29 (DK GRN) between the horn relay connector cavity 30 and the horn connector cavity B.

Is the repair complete?

--

System OK

--

17

Locate and repair the open in CKT 28 (BLK) between the horn relay connector cavity 86 and cavity G of the turn signal switch connector.

Is the repair complete?

--

System OK

--

18

Replace the horn switch. Refer to Horn Switch Replacement - On Vehicle in Steering Wheel and Column- Tilt.

Is the repair complete?

--

System OK

--

19

Replace the horn relay.

Is the repair complete?

--

System OK

--

20

Replace the horn(s).

Is the repair complete?

--

System OK

--