Vehicle Theft Security

909B-AUXILIARY HORN PRIVATE BUS COMMUNICATION ERROR





For a complete wiring diagram Consult Diagrams/Electrical

- When Monitored:
Continuously while the VTSS is armed.

- Set Condition:
If the Roof Control Module does not receive messages from the Siren.





Diagnostic Test

1. INTERMITTENT DTC
With the scan tool, erase the current Roof Control Module DTC's.
Turn the ignition off.
Arm the VTSS and wait 1 minute.
Disarm the VTSS and turn the ignition on.
Does the scan tool display the same DTC?

Yes

- Go To2

No

- The condition that caused this symptom is currently not present. Inspect the related wiring harness for a possible intermittent condition. Look for any chafed, pierced, pinched or partially broken wires.
- Perform BODY VERIFICATION TEST - VER 1.Verification Tests

2. SIREN CONTROL CIRCUIT SHORT TO GROUND
Disconnect the Siren harness connector.
Disconnect the Roof Control Module harness C1 connector.
Measure the resistance between ground and the Siren Control circuit at the Roof Control Module harness C1 connector.
Is the resistance below 5.0 ohms?

Yes

- Repair the Siren Control circuit for a short to ground.

No

- Go To3
- Perform BODY VERIFICATION TEST - 1A.Verification Tests

3. SIREN CONTROL CIRCUIT OPEN
Measure the resistance of the Siren Control circuit between the Roof Control Module and the Siren connector.
Is the resistance below 3.0 ohms?

Yes

- Replace the Siren and using the scan tool under RCM Miscellaneous Function perform the Anti-Theft Alarm Siren Learn routine.
- Perform BODY VERIFICATION TEST - VER 1.Verification Tests

No

- Repair the Siren Control circuit for an open.
- Perform BODY VERIFICATION TEST - 1A.Verification Tests