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

  1. Locate and repair the source of the overload in CKT 40 (ORN).
  2. Replace the fuse.

Did you complete the repair?

--

System OK

--

3

Inspect the condition of G200 (P42), or G200 and G102 (P32).

Are the grounds clean and tight?

--

Go to Step 5

Go to Step 4

4

Repair G200 or G102 as necessary.

Did you complete the repair?

--

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 from 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.

Did you complete the repair?

--

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.

Did you complete the repair?

--

System OK

--

11

Locate and repair the open in CKT 150 (BLK) between the horn connector cavity A and G200 (P42), or G102 (P32).

Did you complete the repair?

--

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. 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?

1.0 ohms

Go to Step 17

Go to Step 15

15

Measure the 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?

5.0 ohms

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.

Did you complete the repair?

--

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.

Did you complete the repair?

--

System OK

--

18

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

Did you complete the repair?

--

System OK

--

19

Replace the horn relay.

Did you complete the repair?

--

System OK

--

20

Replace the horn(s).

Did you complete the repair?

--

System OK

--