P1607
P1607-PCM INTERNAL SHUTDOWN TIMER RATIONALITY TOO SLOW
For a complete wiring diagram, refer to the Wiring Information.
Theory of Operation
The Powertrain Control Module (PCM) compares actual shutdown time to a calculated shutdown time value. The calculated shut down time value is based on the amount the Engine Coolant Temperature (ECT) should drop after a completely warmed up engine is shut down for a minimum of 8 hours. If the difference between actual shutdown time and the calculated shut down time is greater than a maximum value, a one trip failure will set. The shutdown time is measured again after 1 hour of ignition off time following the next engine warm up cycle. The PCM compares the shutdown time to a calculated value. If the difference is greater than a maximum value, the MIL is illuminated and a DTC will set.
- When Monitored:
With the engine running after a cycle when a complete engine warm up was achieved, the difference between engine coolant temperature and ambient air temperature less than or equal to 10°C (50°F) and battery voltage greater than 10.0 volts.
- Set Conditions:
This DTC sets if the engine coolant temp does not drop enough or drops too much during engine off time. This DTC may also set if the controller timer is inaccurate. Two Trip Fault.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.
Diagnostic Test
1. POWERTRAIN CONTROL MODULE (PCM)
1. Turn the ignition on.
2. With the scan tool monitor the Ignition Off Time value.
3. 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.
4. With the scan tool 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
- Go To 2
No
- Replace and program the Powertrain Control Module (PCM). .
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
2. ENGINE COOLANT INSPECTION
NOTE:
This DTC will set if the engine cools quicker than it should compared to engine off times. If the customer washed a hot engine with the engine off, a One Trip Failure will 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 this DTC may set.
1. Turn the ignition off.
2. Allow the engine to cool enough to allow the pressure in the coolant system to drop enough to safely remove the radiator cap.
3. Inspect coolant for contamination, correct mixture, and incorrect coolant type.
4. Check the coolant level.
Is the engine coolant level filled to the proper level?
Yes
- Go To 3
No
- Add the appropriate type and amount of engine coolant and perform a cooling system pressure test to check for leaks.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
3. ENGINE COOLANT TEMPERATURE SENSOR
1. Turn the ignition on.
2. Measure engine coolant temperature with an infrared thermometer upstream of the thermostat housing.
3. Using the scan tool, monitor the ECT Sensor temperature and compare it to the measured engine coolant temperature.
Does the ECT Sensor temperature match the measured coolant temperature?
Yes
- Bleed air from cooling system, clear DTCs, and retest for faults. An intermittent fault may be present. If P1607 returns, monitor freeze frame data to determine ECT value when the fault occurred
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Inspect the ECT Sensor connector and PCM connector for corrosion and poor terminal fit. Check the 5-volt supply circuit at the ECT Sensor. Check the resistance of the sensor signal and return circuits for high resistance (above 5.0 Ohms). If the wiring checks ok replace the Thermostat.