
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

Symptom:
*NO RESPONSE FROM CONTROLLER ANTILOCK BRAKE
POSSIBLE CAUSES
NO RESPONSE FROM CAB
GROUND CIRCUIT OPEN
OPEN FUSED IGNITION SWITCH OUTPUT CIRCUIT
OPEN PCI BUS CIRCUIT
CONTROLLER ANTILOCK BRAKE
TEST ACTION APPLICABILITY
1 Turn the ignition on.
Note: As soon as one or more module communicates with the DRB, answer
the question.
With the DRB, attempt to communicate with the Airbag Control Module (ACM).
With the DRB, attempt to communicate with the Body Control Module (BCM).
Was the DRB able to I/D or establish communications with either of the modules?All
Ye s®Go To 2
No®Refer to the Communications category and perform the symptom
PCI Bus Communication Failure.
Perform ABS VERIFICATION TEST - VER 1.
2 Turn the ignition off.
Disconnect the CAB harness connector.
Measure the resistance between ground and both ground circuits.
Is the resistance below 5.0 ohms for both measurements?All
Ye s®Go To 3
No®Repair the ground circuit(s) for an open.
Perform ABS VERIFICATION TEST - VER 1.
3 Turn the ignition off.
Disconnect the CAB harness connector.
Turn the ignition on.
Using a 12-volt test light connected to ground, probe the Fused Ignition Switch
Output circuit.
Is the test light illuminated?All
Ye s®Go To 4
No®Repair the Fused Ignition Switch Output circuit for an open.
Perform ABS VERIFICATION TEST - VER 1.
399
COMMUNICATION

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.
Disconnect the CAB 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 CAB 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 ABS VERIFICATION TEST - VER 1.
5 If there are no possible causes remaining, view repair. All
Repair
Replace the Controller Antilock Brake in accordance with the
Service Information.
Perform ABS VERIFICATION TEST - VER 1.
400
COMMUNICATION
*NO RESPONSE FROM CONTROLLER ANTILOCK BRAKE ÐContinued

Symptom:
*NO RESPONSE FROM ECM (PCI BUS) - DIESEL ONLY
POSSIBLE CAUSES
ECM PCI NO RESPONSE
PCI BUS CIRCUIT OPEN
ENGINE CONTROL MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition on.
NOTE: As soon as one or more module communicates with the DRB, answer
the question.
With the DRB, enter Body then Body Computer.
With the DRB, enter Anti-Lock Brakes.
With the DRB, enter Body then Electro/Mechanical Cluster (MIC).
With the DRB, enter Passive Restraints then Airbag.
Were you able to establish communications with any of the modules?All
Ye s®Go To 2
No®Refer to symptom PCI Bus Communication Failure in the Com-
munications category.
Perform ROAD TEST VERIFICATION - VER-2.
2 With the DRB read ECM Diagnostic Trouble Codes. This is to ensure power and
grounds to the ECM are operational.
NOTE: If the DRB will not read ECM DTC's, follow the NO RESPONSE TO
ECM (SCI only) symptom path, if vehicle will start. For NO START Condi-
tions follow the no start symptom in the Starting category.
Turn the ignition off.
Disconnect the ECM harness connectors.
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 ground. Connect the Red lead to the PCI Bus circuit in the
ECM 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®Replace and program the Engine Control Module in accordance
with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.
No®Repair the PCI Bus circuit for an open.
Perform ROAD TEST VERIFICATION - VER-2.
401
COMMUNICATION

Symptom:
*NO RESPONSE FROM FRONT CONTROL MODULE
POSSIBLE CAUSES
ATTEMPT TO COMMUNICATE WITH ANOTHER MODULE
OPEN GROUND CIRCUIT(S)
OPEN PCI BUS CIRCUIT
FRONT 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.
With the DRB, attempt to communicate with the Body Control Module (BCM).
Was the DRB able to I/D or communicate with any of the modules?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.
Remove the Front Control Module from the IPM.
Measure the resistance between ground and both Ground circuits.
Is the resistance below 10.0 ohms for each measurement?All
Ye s®Go To 3
No®Repair the Ground circuit(s) for an open.
Perform BODY VERIFICATION TEST - VER 1.
404
COMMUNICATION

Symptom:
*NO RESPONSE FROM PCM (PCI BUS)
POSSIBLE CAUSES
PCM PCI NO RESPONSE
PCI BUS CIRCUIT OPEN
POWERTRAIN CONTROL MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition on.
NOTE: As soon as one or more module communicates with the DRB, answer
the question.
With the DRB, enter Body then Body Computer.
With the DRB, enter Anti-Lock Brakes.
With the DRB, enter Body then Electro/Mechanical Cluster (MIC).
With the DRB, enter Passive Restraints then Airbag.
Were you able to establish communications with any of the modules?All
Ye s®Go To 2
No®Refer to symptom PCI Bus Communication Failure in the Com-
munications category.
Perform POWERTRAIN VERIFICATION TEST VER - 1.
2 With the DRB read PCM Diagnostic Trouble Codes. This is to ensure power and
grounds to the PCM are operational.
NOTE: If the DRB will not read PCM DTC's, follow the NO RESPONSE TO
PCM (SCI only) symptom path, if vehicle will start. For NO START Condi-
tions follow symptom NO RESPONSE in Starting category.
Turn the ignition off.
Disconnect the PCM 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 PCM ground. Connect the Red lead to the PCI Bus
circuit in the PCM 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®Replace the Powertrain Control Module in accordance with the
Service Information.
Perform POWERTRAIN VERIFICATION TEST VER - 1.
No®Repair the PCI Bus circuit for an open.
Perform POWERTRAIN VERIFICATION TEST VER - 1.
412
COMMUNICATION

TEST ACTION APPLICABILITY
3 Turn the ignition off.
Disconnect the TCM harness connector.
Remove the starter relay from the IPM.
Using a 12-volt test light connected to ground, probe the Ignition Switch Output
(Start) circuit.
Note: The light must illuminate brightly, if it does not light, or lights dimly,
the circuit must be repaired. If there is any doubt, compare the brightness
when testing the circuit, to the brightness when connected directly to the
battery positive post.
Observe the test light while momentarily turning the ignition switch to the Start
position.
Is the test light illuminated?All
Ye s®Go To 4
No®Repair the Ignition Switch Output (Start) circuit for an open.
Refer to the wiring diagrams located in the Service Information.
Perform 41TE TRANSMISSION VERIFICATION TEST - VER 1.
Note: Reinstall the original Starter Relay.
4 Turn the ignition off.
Disconnect the TCM harness connector.
Using a 12-volt test light connected to ground, probe the Fused B(+) circuit.
Note: The light must illuminate brightly, if it does not light, or lights dimly,
the circuit must be repaired. If there is any doubt, compare the brightness
when testing the circuit, to the brightness when connected directly to the
battery positive post.
Is the test light illuminated?All
Ye s®Go To 5
No®Check IPM fuse #15 for an open. If OK, repair the Fused B(+)
circuit for an open. Refer to the wiring diagrams located in the
Service Information.
Perform 41TE TRANSMISSION VERIFICATION TEST - VER 1.
5 Turn the ignition off.
Disconnect the TCM harness connector.
Using a 12-volt test light connected to 12-volts, probe each ground circuit in the TCM
connector.
NOTE: The light must illuminate brightly, if it does not light, or lights dimly,
the circuit must be repaired. If there is any doubt, compare the brightness
when testing the circuit, to the brightness when connected directly to the
battery negative post.
Is the light illuminated at all ground circuits?All
Ye s®Go To 6
No®Repair the Ground circuit(s) for an open. Check the main ground
connection to engine block and/or chassis. Refer to the wiring
diagrams located in the Service Information.
Perform 41TE TRANSMISSION VERIFICATION TEST - VER 1.
421
COMMUNICATION
*NO RESPONSE FROM TRANSMISSION CONTROL MODULE ÐContinued

Symptom:
*LEFT FRONT DOOR AJAR SWITCH SENSE CIRCUIT OPEN
POSSIBLE CAUSES
INTERMITTENT CONDITION
LEFT FRONT DOOR AJAR SWITCH GROUND CIRCUIT OPEN
LEFT FRONT DOOR LOCK MOTOR/AJAR SWITCH
LEFT FRONT DOOR AJAR SWITCH SENSE CIRCUIT OPEN
BODY CONTROL MODULE INTERNAL MALFUNCTION
TEST ACTION APPLICABILITY
1 Open the driver door.
With the DRBIIItin Inputs/Outputs, read the DR DOOR AJAR SW state.
Does the DRBIIItdisplay CLOSED?All
Ye s®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.
No®Go To 2
2 Disconnect the Left Front Door Lock Motor/Ajar switch connector.
Using a 12-volt Test Light connected to 12-volts, test the Ground circuit for
continuity.
Does the light illuminate?All
Ye s®Go To 3
No®Repair the Ground circuit for an open.
Perform BODY VERIFICATION TEST - VER 1.
3 Disconnect the Left Front Door Lock Motor/Ajar Switch connector.
With the DRBIIItin Inputs/Outputs, read the DR DOOR AJAR SW state.
Connect a jumper wire between Sense circuit and the Ground circuit.
Does the DRBIIItdisplay DR DOOR AJAR SW: CLOSED?All
Ye s®Replace the Left Front Door Lock Motor/Ajar Switch.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 4
4 Disconnect the Body Control Module C3 harness connector.
Disconnect the Left Front Door Lock Motor/Ajar Switch harness connector.
Measure the resistance of the Sense circuit.
Is the resistance below 5.0 ohms?All
Ye s®Replace the Body Control Module.
Perform BODY VERIFICATION TEST - VER 1.
No®Repair the Left Front Door Ajar Switch Sense circuit for an open.
Perform BODY VERIFICATION TEST - VER 1.
428
DOOR AJAR