For 1990-2009 cars

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Is the vehicle equipped with UA6 (theft deterrent system)? | -- | Go to Step 2 | Go to Step 3
2 | Test the vehicle for body control module DTCs. Refer to Diagnostic Trouble Code (DTC) Displaying in Body Control Systems. Are any DTCs present? | -- | Refer to the Diagnostic Trouble Code (DTC) List/Type in Body Control Systems | Go to Step 3
3 |

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

Does the test lamp illuminate?

--

Go to Step 4

Go to Step 5

4 | Connect a test lamp between horn relay terminal 30 and a good ground. Does the test lamp illuminate? | -- | Go to Step 6 | Go to Step 5
5 |

1. Test for a poor connection at horn relay terminals 86 or 30.
2. If the connection is OK, replace the underhood accessory wiring junction block. Refer to Fuse Block Replacement in Wiring Systems.

Did you complete the repair?

--

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 illuminate?

--

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 15 amp fused jumper between the spring loaded terminal leading toward the underhood accessory wiring junction block and a good ground.

Does the test lamp illuminate?

--

Go to Step 9

Go to Step 8

8 | Repair the short to B+ power or an open in CKT 28. Did you complete the repair? | -- | 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.

• | For a Chevrolet refer to Steering Wheel Replacement in Steering Wheel and Column - Tilt.

• | For a 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. For a Pontiac or an Oldsmobile, refer to Inflatable Restraint Steering Wheel Module Replacement in SIR.

Did you complete the repair?

--

System OK

--

10 | Momentarily connect a 15 amp fused jumper between horn relay terminal 30 and terminal 87. Do the horns operate? | -- | Go to Step 11 | Go to Step 12
11 | Replace the horn relay. Did you complete the repair? | -- | System OK | --
12 |

1. Disconnect either of the horn connectors.
2. Connect a 15 amp fused jumper from terminal A of the horn to the negative battery terminal.
3. Connect another jumper from terminal B of the horn to the positive battery terminal.

Does the horn operate?

--

Go to Step 14

Go to Step 13

13 | Replace the inoperative horns. Refer to Horn Replacement . Did you complete the repair? | -- | System OK | --
14 | 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. Did you complete the repair? | -- | System OK | --
16 | Repair an open in CKT 29, between the underhood accessory wiring junction block and the inoperative horn(s). Did you complete the repair? | -- | System OK | --