For 1990-2009 cars

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
DEFINITION: One or both of the horns are inoperative
1 | Was the Horns System Check performed? | -- | Go to Step 2 | Refer to Horns System Check
2 |

1. Install the scan tool.
2. Select the miscellaneous test in special functions.
3. Command the BCM to turn ON the horns.

Do both horns sound for as long as the BCM has them turned ON?

--

Go to Step 13

Go to Step 3

3 |

1. Disconnect the horn #1 connector.
2. Use the DMM to measure the voltage between terminal 2 of the horn #1 connector and a known good ground.
3. Repeat steps 1 and 2 for horn #2.

Is the measured voltage within the specified value?

B+

Go to Step 5

Go to Step 4

4 |

1. Check the horn fuse for an open.
2. If the horn fuse is OK, locate an open or a high resistance in the following circuits:

• | A17

• | A18

• | A30

• | 301

3. Repair the open or the high resistance in any one of these circuits.

Is the repair complete?

--

Go to Step 17

--

5 |

1. Connect the horn #1 and horn #2 connectors.
2. Remove the horn relay K63 from the relay box.
3. Connect a fused jumper between terminal 4 and terminal 8 of the relay box.

Do both horns sound?

--

Go to Step 7

Go to Step 6

6 |

1. Locate an open or a high resistance in circuits XM60, XM65, XM70, XM30 and/or F700.
2. Repair the open or the high resistance in any one of these circuits.
3. If all of these circuits are OK, replace horn #1 and/or horn #2. Refer to Horn Replacement in Horns.

Is the repair or replacement complete?

--

Go to Step 17

--

7 | Use the DMM in order to measure the voltage between terminal 2 of the horn relay K63, and a known good ground. Is the measured voltage within the specified value? | B+ | Go to Step 9 | Go to Step 8
8 |

1. Locate an open or a high resistance in circuit A121.
2. Repair the open or the high resistance in circuit A121.

Is the repair complete?

--

Go to Step 17

--

9 | While commanding the BCM to activate the horns, use the DMM in order to measure the voltage between terminal 2 and 6 of the horn relay K63. Is the measured voltage within the specified value? | B+ | Go to Step 10 | Go to Step 11
10 | Replace the horn relay K63. Is the replacement complete? | -- | Go to Step 17 | --
11 |

1. Disconnect the BCM connector C2.
2. Use the DMM to measure the resistance between terminal 6 of the relay box and terminal C4 of the BCM connector C2.

Is the measured resistance less than the specified value?

5 ohms

Go to Step 16

Go to Step 12

12 |

1. Locate an open or a high resistance in circuit XM899.
2. Repair the open or the high resistance in circuit XM899.

Is the repair complete?

--

Go to Step 17

--

13 |

1. Remove the horn switch.
2. Remove the horn relay K63 from the relay box.
3. Connect a jumper between terminal A and terminal B of the horn switch connector.
4. Use the DMM to measure the resistance between terminal 6 of the relay box and a known good ground.

Is the measured resistance less than the specified value?

5 ohms

Go to Step 15

Go to step 14

14 |

1. Locate an open or a high resistance in circuits XM1, X1 and/or F122.
2. Repair the open or the high resistance in circuits XM1, X1 and/or F122.
3. Replace the inflatable restraint steering wheel module coil if these circuits are OK. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement in SIR.

Is the repair or replacement complete?

--

Go to Step 17

--

15 | Replace the horn switch. Refer to Horn Switch Replacement - On Vehicle in Steering Wheel and Column On-Vehicle Service. Is the replacement complete? | -- | Go to Step 17 | --
16 | Replace the BCM. Is the replacement complete? | -- | Go to Step 17 | --
17 |

1. Connect all connectors and components that were disconnected.
2. Verify that both horns operate properly.

Do both of the horns operate properly?

--

System OK

Go to Step 1