Symptom:
*NO RESPONSE FROM PCM (PCI BUS) - NGC
POSSIBLE CAUSES
PCM PCI NO RESPONSE
POWERTRAIN CONTROL MODULE
PCI BUS CIRCUIT OPEN
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 Anti-Lock Brakes.
With the DRB, enter Electro/Mechanical Cluster (MIC).
With the DRB, enter Passive Restraints then Airbag.
Were you able to establish communications with any of the modules?
All
Yes → 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 the Powertrain DTC’s. Thisis toensure powerand groundsto the
PCM are operational.
NOTE: If the DRB will not read PCM DTC’s, follow the NO RESPONSE TO
PCM (PCM SCI only) symptom path.
Turn the ignition off.
Disconnect the PCM harness connectors.
CAUTION: DONOT PROBETHE PCM HARNESS CONNECTORS. PROBING
THE PCM HARNESS CONNECTORS WILL DAMAGE THE PCM TERMI-
NALS RESULTING IN POOR TERMINAL TO PIN CONNECTION. INSTALL
MILLER SPECIAL TOOL #8815 TO PERFORM DIAGNOSIS.
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 DRBIIIt select 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 appropriate terminal of special tool #8815.
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
Yes → Replace and program the Powertrain Control Module in accor-
dance 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.
109
COMMUNICATION
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