P1607

P1607-PCM INTERNAL SHUTDOWN TIMER RATIONALITY





For a complete wiring diagram REFER to DIAGRAMS/ELECTRICAL .

Theory of Operation


The PCM compares actual shutdown time to a calculated value, which is based on the amount the ECT should drop after a completely warmed up engine is shut down for a minimum of 8 hours. If the difference is greater than a maximum value, a pending DTC will set.


- When Monitored:
After a complete engine warm up then ignition off time of greater than 8 hours, with the engine running, the difference between ECT and AAT less than or equal to 10 C (50 F), and battery voltage above 10 volts.

- Set Condition:
If the measured shutdown time is significantly less than an expected shutdown time based on how much the ECT has dropped, a one trip failure sets. If this happens again after another warm up and 1 hour engine off period, the MIL will set







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.Initial Inspection and Diagnostic Overview


Diagnostic Test


1. ENGINE COOLANT INSPECTION
NOTE: This DTC will set if the engine cools quicker than it should compared to engine off times. If a hot engine is washed with the ignition off, a pending DTC may set. If the vehicle is parked in a highly ventilated area or has a large fan blowing on it which might cause the engine to cool quicker than expected, a pending DTC may set.

WARNING: Do not remove or loosen the radiator cap with the system hot and under pressure. Serious burns from coolant can occur.

Turn the ignition off.
Allow the engine to cool enough to allow the pressure in the coolant system to drop enough to safely remove the radiator cap.
Check the coolant level and condition.
Is the engine coolant level filled to the proper level?

Yes


- Go to 2


No


- Add the appropriate type and amount of engine coolant and retest.
- Perform the PCM Verification Test.Powertrain Verification Test


2. IGNITION OFF TIMER
Turn the ignition on.
With the scan tool under PCM/NGC Data Display, locate the Ignition Off Time value.
While monitoring a stop watch, turn the Ignition off for 10 minutes, watch the stop watch for those 10 minutes, and then turn the Ignition on.
With the scan tool under Data Functions, check the Ignition Off Time value again.
Does the Ignition Time Off value on the scan tool match the actual time you had the Ignition off on the stop watch?

Yes


- The conditions that set the DTC are not active at this time. Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Checking For An Intermittent DTC


No


- Go to 3


3. CHECKING THE PCM POWER AND GROUND CIRCUITS
Perform the diagnostic procedure for *CHECKING THE PCM POWER AND GROUND CIRCUITS. Checking the PCM Power and Ground Circuits

Were any problems found?

Yes


- Repair the PCM power and ground circuit(s) as necessary and retest.
- Perform the PCM Verification Test.Powertrain Verification Test


No


- Go to 4


4. POWERTRAIN CONTROL MODULE (PCM)
Verify that the PCM is operating at the latest software version available.
Refer to any Technical Service Bulletins that may apply.

Were any problems found?

Yes


- Repair as necessary and retest.
- Perform the PCM Verification Test.Powertrain Verification Test


No


- Replace and program the Powertrain Control Module (PCM).
- Perform the PCM Verification Test.Powertrain Verification Test