57 Horn Relay Coil Open/Short To Ground

57-HORN RELAY COIL OPEN/SHORT TO GROUND





For a complete wiring diagram, refer to the Wiring Information Electrical Diagrams.

- When Monitored:
Continuously.

- Set Condition:
When the Body Control Module (BCM) does not detect voltage on the (X4) Horn Relay Control circuit.





1. TEST FOR INTERMITTENT CONDITION
1. Turn the ignition on.
2. With the scan tool, erase current BCM Diagnostic Trouble Codes (DTCs).
3. Turn the ignition off, wait 10 seconds, then turn the ignition on.
4. Operate the Horn Switch several times.
5. With the scan tool, read the current BCM DTCs.

Does the scan tool display DTC HORN RELAY COIL OPEN/SHORT TO GROUND?

Yes

- Go To 2

No

- The conditions that caused this code to set are not present at this time. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
- Perform BODY VERIFICATION TEST. Body Verification Test.

2. CHECK FOR OPEN PDC FUSE #B19




1. Inspect PDC Fuse #B19.

Is the fuse open?

Yes

- Go To 3

No

- Go To 8

3. REPLACE AND RECHECK PDC FUSE #B19




1. Turn the ignition off.
2. Install a new PDC Fuse #B19.
3. Turn the ignition on.
4. Operate the Horn Switch several times.
5. Inspect PDC Fuse #B19.

Is the fuse open?

Yes

- Go To 4

No

- Using the wiring diagram/schematic as a guide, inspect the wiring and connectors for the cause of the open fuse and repair as necessary.
- Perform BODY VERIFICATION TEST. Body Verification Test.

4. CHECK (A43) FUSED B(+) CIRCUIT FOR A SHORT TO GROUND




1. Turn the ignition off.
2. Remove PDC Fuse #B19.
3. Remove the Horn Relay.
4. Measure the resistance of the (A43) Fused B(+) circuit between ground and the Horn Relay connector.

Is the resistance below 10K Ohms?

Yes

- Repair the (A43) Fused B(+) circuit for a short to ground or replace the Power Distribution Center (PDC) as necessary. Replace Fuse #B19.
- Perform BODY VERIFICATION TEST. Body Verification Test.

No

- Go To 5

5. CHECK (X2) HORN RELAY OUTPUT CIRCUIT FOR A SHORT TO GROUND




1. Disconnect the Horn 1 and Horn 2 connector.

NOTE: Check connectors. Clean and repair as necessary.

2. Measure the resistance of the (X2) Horn Relay Output circuit between ground and the Horn Relay connector.

Is the resistance below 10K Ohms?

Yes

- Repair the (X2) Horn Relay Output circuit for a short to ground or replace the Power Distribution Center (PDC) as necessary. Replace Fuse #B19.
- Perform BODY VERIFICATION TEST. Body Verification Test.

No

- Go To 6

6. CHECK FOR A SHORTED HORN RELAY
1. Reconnect the Horn 1 and Horn 2 connector.
2. Substitute the original Horn Relay with a known good relay.
3. Install a new PDC Fuse #B19.
4. Turn the ignition on.
5. Operate the Horn Switch several times.
6. Inspect PDC Fuse #B19.

Is the fuse open?

Yes

- Go To 7

No

- Replace the original Horn Relay.
- Perform BODY VERIFICATION TEST. Body Verification Test.

7. CHECK FOR A SHORTED HORN




1. Turn the ignition off.
2. Disconnect the Horn 1 connector.
3. Install a new PDC Fuse #B19.
4. Turn the ignition on.
5. Operate the Horn Switch several times.
6. Inspect PDC Fuse #B19.

Is the fuse open?

Yes

- Replace Horn 2 and Fuse #B19. Reinstall the original Horn Relay.
- Perform BODY VERIFICATION TEST. Body Verification Test.

No

- Replace Horn 1. Reinstall the original Horn Relay.
- Perform BODY VERIFICATION TEST. Body Verification Test.

8. CHECK (A0) B(+) CIRCUIT FOR AN OPEN




1. If not done previously, turn the ignition off, and then remove PDC Fuse #B19.
2. Turn the ignition on.
3. Using a 12-volt test light connected to ground, check the (A0) B(+) circuit at PDC Fuse #B19 connector. NOTE: The test light must illuminate brightly. Compare the brightness to that of a direct connection to the battery.

Does the test light illuminate brightly?

Yes

- Go To 9

No

- Repair the (A0) B(+) circuit for an open.
- Perform BODY VERIFICATION TEST. Body Verification Test.

9. CHECK (A43) FUSED B(+) CIRCUIT FOR AN OPEN




1. Turn the ignition off.
2. Remove the Horn Relay.
3. Reinstall PDC Fuse #B19.
4. Turn the ignition on.
5. Using a 12-volt test light connected to ground, check the (A43) Fused B(+) circuit at the Horn Relay connector. NOTE: The test light must illuminate brightly. Compare the brightness to that of a direct connection to the battery.

Does the test light illuminate brightly?

Yes

- Go To 10

No

- Repair the (A43) Fused B(+) circuit for an open or replace the Power Distribution Center (PDC) as necessary.
- Perform BODY VERIFICATION TEST. Body Verification Test.

10. CHECK FOR AN OPEN HORN RELAY
1. Turn the ignition off.
2. Substitute the original Horn Relay with a known good relay.
3. Turn the ignition on.
4. With the scan tool, erase the current BCM DTCs.
5. Turn the engine off, wait 10 seconds, then turn the ignition on.
6. Operate the Horn Switch.
7. With the scan tool, read the current BCM DTCs.

Does the scan tool display the same DTC?

Yes

- Go To 11

No

- Replace the original Horn Relay.
- Perform BODY VERIFICATION TEST. Body Verification Test.

11. CHECK (X4) HORN RELAY CONTROL CIRCUIT FOR A SHORT TO GROUND




1. Turn the ignition off.
2. Remove the replacement Horn Relay.
3. Disconnect BCM C4 connector.
4. Measure the resistance of the (X4) Horn Relay Control circuit between ground and the Horn Relay connector.

Is the resistance below 10K ohms?

Yes

- Repair the (X4) Horn Relay Control circuit for a short to ground or replace the Power Distribution Center (PDC) as necessary.
- Perform BODY VERIFICATION TEST. Body Verification Test.

No

- Go To 12

12. CHECK (X4) HORN RELAY CONTROL CIRCUIT FOR AN OPEN




1. Measure the resistance of the (X4) Horn Relay Control circuit between the BCM C4 connector and the Horn Relay connector.

Is the resistance below 5.0 ohms?

Yes

- Replace the Body Control Module (BCM).
- Perform BODY VERIFICATION TEST. Body Verification Test.

No

- Repair the (X4) Horn Relay Control circuit for an open or replace the Power Distribution Center (PDC) as necessary.
- Perform BODY VERIFICATION TEST. Body Verification Test.