Horn

HORNS INOPERATIVE

Horns Inoperative:

POSSIBLE CAUSES
- DTC present
- Fuse #45
- Horns
- Horn ground circuit open
- Horn relay output circuit open
- Horn switch
- Horn switch ground
- Clockspring
- Horn switch sense open
- Integrated power module
- Instrument cluster
- Front control module

Diagnostic Test

1. HORN RELAY CONTROL CIRCUIT DTC ACTIVE
Turn the ignition on.
With the DRBIII(R), read FCM DTC's.

Q: Does the DRBIII(R) display a HORN RELAY CONTROL CIRCUIT DTC active?

YES: Refer to symptom list. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Go To 2

2. ACTUATE HORN RELAY
With the DRBIII(R), actuate the Horn Relay.

Q: Do the horns operate?

YES: Go To 3
NO: Go To 7

3. HORN SWITCH

WARNING: TURN THE IGNITION OFF, DISCONNECT THE BATTERY AND WAIT TWO MINUTES BEFORE PROCEEDING.

CAUTION: Do not place an intact undeployed airbag face down on a hard surface, the airbag will propel into the air if accidentally deployed, and could result in serious or fatal injury.

Gain access to the horn switch.
Measure the resistance of the Horn Switch ground circuit.

Q: Is the resistance below 5.0 ohms?

YES: Go To 4
NO: Repair the horn switch ground as necessary. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

4. HORN SWITCH

WARNING: TURN THE IGNITION OFF, DISCONNECT THE BATTERY AND WAIT TWO MINUTES BEFORE PROCEEDING.

CAUTION: Do not place an intact undeployed airbag face down on a hard surface, the airbag will propel into the air if accidentally deployed, and could result in serious or fatal injury.

Gain access to the horn switch connector.

WARNING: TURN THE IGNITION ON, THEN RECONNECT THE BATTERY.

Momentarily connect a jumper wire between the Horn Switch Sense circuit at the Horn switch connector and ground.

Q: Did the horns sound?

YES: Replace the horn switch. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Go To 5

5. CLOCKSPRING




Turn the ignition off.
Disconnect the clockspring C1 connector.
Momentarily connect a jumper wire between the Horn Switch Sense circuit at the clockspring connector and ground.

Q: Did the horns sound?

YES: Replace the clockspring. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Go To 6

6. HORN SWITCH SENSE




Turn the ignition off.
Disconnect the clockspring C1 connector.
Disconnect the Instrument Cluster C3 connector.

NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance of the Horn Switch Sense circuit between the clockspring C1 connector and the Instrument Cluster C3 connector.

Q: Is the resistance below 5.0 ohms?

YES: Replace the Instrument Cluster. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Repair the Horn Switch Sense circuit for an open. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

7. CHECK FUSE #45




Turn the ignition off.
Using a 12-volt test light connected to ground, check the Horn fuse #45 in the IPM.

Q: Is the fuse open?

YES: Replace the fuse. Check for a short to ground in the Horn Relay Output circuit from the IPM to the horns. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Go To 8

8. HORN RELAY OUTPUT




Disconnect a horn connector.
With the DRBIII(R), actuate the Horn Relay.
Using a 12-volt test light connected to ground, check the Horn Relay Output circuit.

Q: Does the test light illuminate brightly?

YES: Go To 9
NO: Go To 10

9. HORN GROUND CIRCUIT OPEN




Turn the ignition off.
Disconnect the Horn connector.
Using a 12-volt test light connected to 12-volts, check the Ground circuit in the horn connector.

Q: Does the test light illuminate brightly?

YES: Replace the Horns. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Repair the Ground circuit for an open. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

10. HORN RELAY OUTPUT CIRCUIT OPEN




Gain access to the IPM C1 connector.
Using a 12-volt test light connected to ground, back probe the Horn Relay Output circuit in the IPM C1 connector.
Turn the ignition on.
With the DRBIII(R), the actuate the horn relay.

Q: Does the test light illuminate brightly?

YES: Repair the Horn Relay Output circuit for an open. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Go To 11

11. INTEGRATED POWER MODULE




Turn the ignition off.
Remove the Front Control Module from the Integrated Power Module.

NOTE:
- Check connectors - Clean/repair as necessary.
- The test light is still connected to the C1 connector.

Momentarily jumper the Horn Relay Control circuit to ground at the FCM connector.

Q: Does the test light illuminate brightly?

YES: Replace the Front Control Module. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Replace the Integrated Power Module. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test