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)

1.VERIFY THAT THE DTC IS ACTIVE

Did this DTC reset?

Yes

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

Is the voltage above 10.0 volts?

Yes

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

Does the test light illuminate brightly?

Yes

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

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.

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).

5.CHECK THE (X75) SIREN SIGNAL CONTROL CIRCUIT FOR A SHORT TO GROUND

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.

6.CHECK THE (X75) SIREN SIGNAL CONTROL CIRCUIT FOR AN OPEN

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).

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.