ITM-NO SERIAL COMMUNICATION (EXPORT ONLY)
For a complete wiring diagram Refer to Section 8W
- When Monitored:
Continuously while the VTSS is armed.
- Set Condition:
If the Intrusion Transceiver Module (ITM) fails to receive messages from the Siren.
| Possible Causes |
| (A908) FUSED B+ CIRCUIT OPEN |
| (Z932) GROUND CIRCUIT OPEN |
| (X75) SIREN SIGNAL CONTROL CIRCUIT SHORTED TO GROUND |
| (X75) SIREN SIGNAL CONTROL CIRCUIT OPEN |
| VTSS SIREN |
| INTRUSION TRANSCEIVER MODULE (ITM) |
Diagnostic Test
1. VERIFY THAT THE DTC IS ACTIVETurn the ignition on.
With the scan tool, erase the ITM DTCs.
Turn the ignition off.
Arm the VTSS and wait one minute.
Disarm the VTSS and turn the ignition on.
With the scan tool, read ITM DTCs.
Did this DTC reset?
Yes
- Go To 2
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 or partially broken wires.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
2. CHECK THE (A908) FUSED B+ CIRCUIT FOR AN OPEN
Disconnect the Siren harness connector.
Measure the voltage of the (A908) Fused B(+) circuit in the Siren harness connector.
Is the voltage above 10.0 volts?
Yes
- Go To 3
No
- Repair the (A908) Fused B+ circuit for an open.
- Perform VTSS VERIFICATION TEST - 1A. (Refer to VTSS VERIFICATION TEST - 1A - STANDARD PROCEDURE) in this Section.
3. CHECK THE (Z932) GROUND CIRCUIT FOR AN OPEN
Turn the ignition off.
Using a 12-volt test light connected to 12 volts, check the (Z932) Ground circuit in the Siren harness connector.
Does the test light illuminate brightly?
Yes
- Go To 4
No
- Repair the (Z932) Ground circuit for an open.
- Perform VTSS VERIFICATION TEST - 1A. (Refer to VTSS VERIFICATION TEST - 1A - STANDARD PROCEDURE) in this Section.
4. CHECK THE (X75) SIREN SIGNAL CONTROL CIRCUIT FUNCTION
Using the DRBIII®, set up the lab scope as follows:
- Turn the ignition on.
- Use the Scope input cable CH7058, Cable to Probe adapter CH7062 and the red and black test probes.
- Connect the scope input cable to the channel one connector on the DRBIII®.
- Attach the red and black leads and the cable to probe adapter to the scope input cable.
- Select DRBIII® Standalone.
- Select lab scope.
- Select Live.
- Select 12 volt square wave.
- Press F2 for Scope.
- Press F2 and use the down arrow to set voltage range to 20 volts. Press F2 again when complete.
Connect the black lead to the chassis ground.
Connect the red lead to the (X75) Siren Signal Control circuit in the Siren harness connector.
Start the engine and hold the engine RPM's above 600.
Observe the voltage displayed on the DRBIII® Lab Scope.
Is there a voltage square wave present for one to two seconds?
Yes
- Replace the VTSS Siren in accordance with the Service Information.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
No
- Go To 5
5. CHECK THE (X75) SIREN SIGNAL CONTROL CIRCUIT FOR A SHORT TO GROUND
Turn the ignition off.
Disconnect the ITM harness connector.
Measure the resistance between ground and the (X75) Siren Signal Control circuit in the Siren harness connector.
Is the resistance below 100.0 ohms?
Yes
- Repair the (X75) Siren Signal Control circuit for a short to ground.
- Perform VTSS VERIFICATION TEST - 1A. (Refer to VTSS VERIFICATION TEST - 1A - STANDARD PROCEDURE) in this Section.
No
- Go To 6
6. CHECK THE (X75) SIREN SIGNAL CONTROL CIRCUIT FOR AN OPEN
Measure the resistance of the (X75) Siren Signal Control circuit between the ITM harness connector and the Siren harness connector.
Is the resistance below 5.0 ohms?
Yes
- Replace the ITM in accordance with the Service Information.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
No
- Repair the (X75) Siren Signal Control circuit for an open.
- Perform VTSS VERIFICATION TEST - 1A. (Refer to VTSS VERIFICATION TEST - 1A - STANDARD PROCEDURE) in this Section.