Symptom List:
P1603-PCM INTERNAL DUAL-PORT RAM COMMUNICATION
P1604-PCM INTERNAL DUAL-PORT RAM READ/WRITE INTEG-
RITY FAILURE
P1607-PCM INTERNAL SHUTDOWN TIMER RATIONALITY
Test Note:
All symptoms listed above are diagnosed using the same tests.
The title for the tests will be P1603-PCM INTERNAL DUAL-
PORT RAM COMMUNICATION.
When Monitored and Set Condition:
P1607-PCM INTERNAL SHUTDOWN TIMER RATIONALITY
When Monitored:
During cold start.
Set Condition:
Compares shut down time to coolant temperature.
POSSIBLE CAUSES
FUSED IGNITION SWITCH OUTPUT (OFF-RUN-START)
PCM INTERNAL FAULURE
TEST
ACTION
APPLICABILITY
1
Turn the ignition off.
Disconnect the PCM harness connector.
CAUTION: DO NOT PROBE THE 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.
Turn the ignition to run.
Using a 12-volt test light connected to ground, probe the Fused Ignition Switch
Output (Off-Run-Start) cavity C1-12 circuit at the appropriate terminal of the special
tool #8815.
NOTE: If the test light illuminates, wiggle the wiring harness to ensure that
the problem is not an intermittent wiring problem.
Does the test light illuminate brightly?
All
Yes
→ Replace the Powertrain Control Module in accordance with the
Service Information.
Perform POWERTRAIN VERIFICATION TEST VER - 1 - NGC.
No
→ Check all related fuses. Repair the Fused Ignition Switch Output
circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 1 - NGC.
494
DRIVEABILITY - NGC