Page 401 of 4284
Symptom:
TCM MESSAGES NOT RECEIVED
When Monitored and Set Condition:
TCM MESSAGES NOT RECEIVED
When Monitored: With the ignition in run, and the IOD fuse installed.
Set Condition: The BCM does not receive any messages from the Transmission Control
Module (TCM) for at least 5 seconds.
POSSIBLE CAUSES
ATTEMPT TO COMMUNICATE WITH THE TCM
BODY CONTROL MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRB, attempt to communicate with the Transmission Control Module.
Was the DRB able to I/D or communicate with the TCM?All
Ye s®Go To 2
No®Refer to the Communication category for the related symptom(s).
Perform BODY VERIFICATION TEST - VER 1.
2 With the DRB, erase DTC's.
Cycle the ignition switch from off to on and wait approximately 1 minute.
With the DRB, read DTC's.
Did this DTC reset?All
Ye s®Replace the Body Control Module.
Perform BODY VERIFICATION TEST - VER 1.
No®Test Complete.
372
COMMUNICATION
Page 402 of 4284

Symptom:
*BUS +/- SIGNALS OPEN FROM AUTOMATIC TEMPERATURE
CONTROL MODULE
POSSIBLE CAUSES
ATTEMPT TO COMMUNICATE WITH THE BCM
GROUND CIRCUIT OPEN
FUSED (B+) CKT OPEN
IGNITION SWITCH CIRCUIT OPEN
OPEN PCI BUS CIRCUIT
AUTOMATIC TEMPERATURE CONTROL MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRB, enter Body then Body Computer.
Was the DRB able to I/D or communicate with the BCM?All
Ye s®Go To 2
No®Refer to the symptom list for problems related to no communica-
tion with the BCM.
Perform BODY VERIFICATION TEST - VER 1.
2 Turn the ignition off.
Disconnect the ATC C2 harness connector.
Measure the resistance between ground and the ground circuit.
Is the resistance below 5.0 ohms?All
Ye s®Go To 3
No®Repair the Ground circuit for an open.
Perform BODY VERIFICATION TEST - VER 1.
3 Turn the ignition off.
Disconnect the ATC C2 harness connector.
Using a 12-volt test light connected to ground, probe the Fused B+ circuit.
Is the test light illuminated?All
Ye s®Go To 4
No®Repair the Fused B+ circuit for an open or short. Refer to the
wiring diagrams in the service information.
Perform BODY VERIFICATION TEST - VER 1.
4 Turn the ignition off.
Disconnect the ATC C2 harness connector.
Turn the ignition on.
Using a 12-volt test light connected to ground, probe the Ignition Switch circuit.
Is the test light illuminated?All
Ye s®Go To 5
No®Repair the Ignition Switch circuit for an open or short. Refer to
the wiring diagrams in the service information.
Perform BODY VERIFICATION TEST - VER 1.
373
COMMUNICATION
Page 403 of 4284

TEST ACTION APPLICABILITY
5Note: Ensure there is PCI Bus communication with other modules on the
vehicle before proceeding. If not, refer to the symptom list from the menu
and repair as necessary.
Disconnect the ATC C2 harness connector.
Use 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 DRB. Attach the
red and black leads and the cable to probe adapter to the scope input cable.
Select DRB 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 PCI Bus
circuit in the ATC connector.
Turn the ignition on.
Observe the voltage display on the DRB Lab Scope.
Does the voltage pulse from 0 to approximately 7.5 volts?All
Ye s®Go To 6
No®Repair the PCI Bus circuit for an open.
Perform BODY VERIFICATION TEST - VER 1.
6 If there are no possible causes remaining, view repair. All
Repair
Replace the Automatic Temperature Control Module.
Perform BODY VERIFICATION TEST - VER 1.
374
COMMUNICATION
*BUS +/- SIGNALS OPEN FROM AUTOMATIC TEMPERATURE CON-
TROL MODULE Ð
Continued
Page 404 of 4284

Symptom:
*BUS +/- SIGNALS OPEN FROM MEMORY SEAT/MIRROR MODULE
POSSIBLE CAUSES
ATTEMPT TO COMMUNICATE WITH THE BCM
FUSED SEAT SWITCH DRIVER CIRCUIT OPEN
GROUND CIRCUIT OPEN
OPEN PCI BUS CIRCUIT
MEMORY SEAT/MIRROR MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRB, enter Body then Body Computer.
Was the DRB able to I/D or communicate with the BCM?All
Ye s®Go To 2
No®Refer to the symptom list for problems related to no communica-
tion with the BCM.
Perform MEMORY SYSTEM VERIFICATION TEST - VER 1.
2 Turn the ignition off.
Disconnect the Memory Seat/Mirror Module C4 harness connector.
Using a 12-volt test light connected to ground, probe the Fused Seat Switch Driver
circuit.
Is the test light illuminated?All
Ye s®Go To 3
No®Check the Power Seat Circuit Breaker for an open or short. If ok,
repair the Fused Seat Switch Driver circuit for an open or short.
Perform MEMORY SYSTEM VERIFICATION TEST - VER 1.
3 Turn the ignition off.
Disconnect the Memory Seat/Mirror Module C4 harness connector.
Measure the resistance between ground and the ground circuit.
Is the resistance below 5.0 ohms?All
Ye s®Go To 4
No®Repair the ground circuit for an open.
Perform MEMORY SYSTEM VERIFICATION TEST - VER 1.
375
COMMUNICATION
Page 405 of 4284

TEST ACTION APPLICABILITY
4Note: Ensure there is PCI Bus communication with other modules on the
vehicle before proceeding. If not, refer to the symptom list from the menu
and repair as necessary.
Turn the ignition off.
Disconnect the Memory Seat/Mirror Module C2 harness connector.
Use 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 DRB. Attach the
red and black leads and the cable to probe adapter to the scope input cable.
With the DRBIIItselect Pep Module Tools.
Select lab scope.
Select Live Data.
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 PCI Bus
circuit in the Memory Seat/Mirror Module connector.
Turn the ignition on.
Observe the voltage display on the DRB Lab Scope.
Does the voltage pulse from 0 to approximately 7.5 volts?All
Ye s®Go To 5
No®Repair the PCI Bus circuit for an open.
Perform MEMORY SYSTEM VERIFICATION TEST - VER 1.
5 If there are no possible causes remaining, view repair. All
Repair
Replace the Memory Seat/Mirror Module.
Perform MEMORY SYSTEM VERIFICATION TEST - VER 1.
376
COMMUNICATION
*BUS +/- SIGNALS OPEN FROM MEMORY SEAT/MIRROR MODULE Ð
Continued
Page 406 of 4284

Symptom:
*BUS +/- SIGNALS OPEN FROM SENTRY KEY IMMOBILIZER MOD-
ULE
POSSIBLE CAUSES
ATTEMPT TO COMMUNICATE WITH THE BCM
GROUND CIRCUIT OPEN
IGNITION SWITCH OUTPUT CIRCUIT OPEN
FUSED B(+) CIRCUIT OPEN
OPEN PCI BUS CIRCUIT
SENTRY KEY IMMOBILIZER MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRB, enter Body then Body Computer.
Was the DRB able to I/D or communicate with the BCM?All
Ye s®Go To 2
No®Refer to the symptom list for problems related to no communica-
tion with the BCM.
Perform SKIS VERIFICATION.
2 Turn the ignition off.
Disconnect the SKIM harness connector.
Measure the resistance between ground and the ground circuit.
Is the resistance below 5.0 ohms?All
Ye s®Go To 3
No®Repair the ground circuit for an open.
Perform SKIS VERIFICATION.
3 Turn the ignition off.
Disconnect the SKIM harness connector.
Turn the ignition on.
Using a 12-volt test light connected to ground, probe the Ignition Switch Output
circuit.
Is the test light illuminated?All
Ye s®Go To 4
No®Repair the Ignition Switch Output circuit for an open.
Perform SKIS VERIFICATION.
4 Turn the ignition off.
Disconnect the SKIM harness connector.
Using a 12-volt test light connected to ground, probe the Fused B(+) circuit.
Is the test light illuminated?All
Ye s®Go To 5
No®Repair the Fused B+ circuit for an open.
Perform SKIS VERIFICATION.
377
COMMUNICATION
Page 407 of 4284

TEST ACTION APPLICABILITY
5Note: Ensure there is PCI Bus communication with other modules on the
vehicle before proceeding. If not, refer to the symptom list from the menu
and repair as necessary.
Disconnect the SKIM harness connector.
Use 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 DRB. Attach the
red and black leads and the cable to probe adapter to the scope input cable.
Select DRB Standalone.
Select lab scope.
Select Live Data.
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 PCI Bus
circuit in the SKIM connector.
Turn the ignition on.
Observe the voltage display on the DRB Lab Scope.
Does the voltage pulse from 0 to approximately 7.5 volts?All
Ye s®Go To 6
No®Repair the PCI Bus circuit for an open.
Perform SKIS VERIFICATION.
6 If there are no possible causes remaining, view repair. All
Repair
Replace and program the Sentry Key Immobilizer Module in
accordance with the Service Information.
Perform SKIS VERIFICATION.
378
COMMUNICATION
*BUS +/- SIGNALS OPEN FROM SENTRY KEY IMMOBILIZER MODULE
Ð
Continued
Page 408 of 4284

Symptom:
*BUS +/- SIGNALS OPEN OR NO RESPONSE FROM BODY CON-
TROL MODULE
POSSIBLE CAUSES
ATTEMPT TO COMMUNICATE WITH ANOTHER MODULE
FUSED (B+) CKT OPEN
OPEN GROUND CIRCUIT(S)
OPEN PCI BUS CIRCUIT
BODY CONTROL MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRB, attempt to communicate with the Airbag Control Module (ACM).
With the DRB, attempt to communicate with the Controller Antilock Brake (CAB)
module.
Was the DRB able to I/D or communicate with the ACM and the CAB?All
Ye s®Go To 2
No®Refer to symptom list for problems related to the PCI Bus
Communication Failure.
Perform BODY VERIFICATION TEST - VER 1.
2 Turn the ignition off.
Disconnect the BCM C2 harness connector.
Using a 12-volt test light connected to ground, probe the Fused B+ circuit.
Is the test light illuminated?All
Ye s®Go To 3
No®Check fuse #14 in the IPM for an open. If ok, repair the Fused B+
circuit for an open or short. Refer to the wiring diagrams in the
service information.
Perform BODY VERIFICATION TEST - VER 1.
3 Turn the ignition off.
Disconnect the BCM C2 harness connector.
Measure the resistance between ground and both Ground circuits.
Is the resistance below 10.0 ohms for each measurement?All
Ye s®Go To 4
No®Repair the Ground circuit(s) for an open.
Perform BODY VERIFICATION TEST - VER 1.
379
COMMUNICATION