P0125

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

While the engine is warming, the VCM monitors the ECT sensor in order to determine how long the engine takes to reach the coolant temperature that is required for closed loop operation.

A DTC sets it the VCM determines that the engine did not reach a closed loop temperature in a specified amount of time. This diagnostic will not run if either the intake air or the engine coolant temperature measure below a predetermined temperature. The VCM will only run this DTC on a cold start and only once per cold start.


CONDITIONS FOR SETTING THE DTC

^ Engine running

^ No ECT sensor short test failure or DTCs

^ No IAT DTCs

^ IAT is greater than -40°C (-40°F)

^ ECT is greater than -40°C (-40°F)

^ Start up ECT is less than or equal to -40°C (-40°F)

Closed Loop Test

^ For a vehicle saturated at -40°C (-40°F):

- Accumulated air flow since start greater than 7500 grams

- Accumulated idle time is less than 360 seconds

^ For a vehicle saturated at -7°C (20°F):

- Accumulated air flow since start greater than 4500 grams

- Accumulated idle time is less than 225 seconds

^ For a vehicle saturated at 10°C (50°F):

- Accumulated air flow since start greater than 1600 grams

- Accumulated idle time is less than 90 seconds

ACTION TAKEN WHEN THE DTC SETS

The VCM turns the MIL ON after 2 consecutive driving cycles with the fault active.

CONDITIONS FOR CLEARING THE MIL/DTC

^ The VCM turns the MIL OFF after 3 consecutive drive trips when the test has Run and Passed and not Failed.

^ A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant temperature exceeds 70°C (160°F) during the same ignition cycle).

^ Use the scan tool Clear Information function.

^ Disconnect the VCM battery feed for 30 seconds.


DIAGNOSTIC AIDS

When a DTC P0125 sets, a skewed ECT sensor or the engine thermostat that does not operate correctly is indicated.

A poor connection, a rubbed through wire insulation, or a wire broken inside of the insulation may cause an intermittent.

Check for the following conditions:

^ A poor connection or a damaged harness. Inspect the VCM harness connector for the following conditions:

- Backed out terminals

- Improper mating

- Broken locks

- Improperly formed or damaged terminals

- Poor terminal to wire connection and

- A damaged harness

^ The intermittent test: If the connections and the harness check OK, monitor a digital voltmeter connected between the VCM terminals while moving the related connectors and the wiring harness. If the failure is induced, the voltage reading changes. This may help in order to isolate the location of the malfunction.

TEST DESCRIPTION

The numbers below refer to the step numbers in the diagnostic table.

3. This test checks the engine warm-up rate.

5. This test checks the coolant sensor reading on the scan tool and the actual coolant temperature.