Diagnostic Test
- TEST FOR INTERMITTENT CONDITION
- Turn the ignition on.
- Using a scan tool, record and erase Diagnostic Trouble Codes (DTCs).
- Operate the Horn Switch several times.
- Cycle the ignition from on to off three times and leave on.
- Using a scan tool, read DTCs.
Does the scan tool display DTC B2336-HORN CONTROL CIRCUIT LOW?
Yes
- Go to step 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 the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
- CHECK FOR OPEN HORN FUSE
- REPLACE AND RECHECK HORN FUSE
- Turn the ignition off.
- Install a new Horn Fuse.
- Turn the ignition on.
- Operate the Horn Switch several times.
- Inspect the Horn Fuse.
Is the fuse open?
Yes
- Go to step 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 the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
- CHECK (A950) FUSED B(+) CIRCUIT FOR A SHORT TO GROUND
- Turn the ignition off.
- Remove the Horn Fuse.
- Remove the Horn Relay.
- Measure the resistance of the (A950) Fused B(+) circuit between ground and the Horn Relay connector.
Is the resistance below 10K Ohms?
Yes
- Replace the Integrated Power Module (IPM) and the Horn Fuse in accordance with the Service Information.
- Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
No
- Go to step 5
- CHECK (X2) HORN RELAY OUTPUT CIRCUIT FOR A SHORT TO GROUND
- CHECK (X2) HORN RELAY OUTPUT CIRCUIT IN IPM FOR A SHORT TO GROUND
- Disconnect the IPM C2 connector.NOTE: Check connectors. Clean and repair as necessary.
- Measure the resistance of the (X2) Horn Relay Output circuit between ground and the Horn Relay connector.
Is the resistance below 10K Ohms?
Yes
- Replace the Integrated Power Module (IPM) and the Horn Fuse in accordance with the Service Information.
- Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
No
- Repair the (X2) Horn Relay Output circuit for a short to ground. Replace the Horn Fuse.
- Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
- Disconnect the IPM C2 connector.
- CHECK FOR A SHORTED HORN RELAY
- Reconnect the Horn 1 and Horn 2 connector.
- Install a known good relay in place of the Horn Relay.
- Install a new Horn Fuse.
- Turn the ignition on.
- Operate the Horn Switch several times.
- Inspect the Horn Fuse.
Is the fuse open?
Yes
- Go to step 8
No
- Replace the original Horn Relay in accordance with the Service Information.
- Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
- CHECK FOR A SHORTED HORN
- Turn the ignition off.
- Disconnect the Horn 1 connector.
- Install a new Horn Fuse.
- Turn the ignition on.
- Operate the Horn Switch several times.
- Inspect the Horn Fuse.
Is the fuse open?
Yes
- Replace Horn 2 and the Horn Fuse in accordance with the Service Information. Reinstall the original Horn Relay.
- Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
No
- Replace Horn 1 in accordance with the Service Information. Reinstall the original Horn Relay.
- Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
- CHECK (A1) B(+) CIRCUIT FOR AN OPEN
- If not done previously, turn the ignition off, and then remove the Horn Fuse.
- Turn the ignition on.
- Using a 12-volt test light connected to ground, check the (A1) B(+) circuit at the Horn Fuse 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 step 10
No
- Repair the (A1) B(+) circuit for an open.
- Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
- CHECK (A950) FUSED B(+) CIRCUIT FOR AN OPEN
- Turn the ignition off.
- Remove the Horn Relay.
- Reinstall the Horn Fuse.
- Turn the ignition on.
- Using a 12-volt test light connected to ground, check the (A950) 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 step 11
No
- Replace the Integrated Power Module (IPM) in accordance with the Service Information.
- Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
- CHECK FOR AN OPEN HORN RELAY
- Turn the ignition off.
- Install a known good relay in place of the Horn Relay.
- Using a scan tool, erase DTCs.
- Operate the Horn Switch several times.
- Cycle the ignition from on to off three times and leave on.
- Using a scan tool, read DTCs.
Does the scan tool display the same DTC?
Yes
- Go to step 12
No
- Replace the original Horn Relay in accordance with the Service Information.
- Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
- CHECK (X4) HORN RELAY CONTROL CIRCUIT FOR A SHORT TO GROUND
- Turn the ignition off.
- Remove the replacement Horn Relay.
- Disconnect the FCM from the Front Control Module IPM 49-way connector.
- Measure the resistance of the (X4) Horn Relay Control circuit between ground and the Horn Relay connector.
Is the resistance below 10K Ohms?
Yes
- Replace the Integrated Power Module (IPM) in accordance with the Service Information.
- Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
No
- Go to step 13
- CHECK (X4) HORN RELAY CONTROL CIRCUIT FOR AN OPEN
- Measure the resistance of the (X4) Horn Relay Control circuit between the Relay connector and the Front Control Module IPM 49-way connector.
Is the resistance below 5.0 Ohms?
Yes
- Replace the Front Control Module (FCM) in accordance with the Service Information.
- Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
No
- Replace the Integrated Power Module (IPM) in accordance with the Service Information.
- Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
- Measure the resistance of the (X4) Horn Relay Control circuit between the Relay connector and the Front Control Module IPM 49-way connector.