P0125

Diagnostic Chart:

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 if 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

The following conditions must be present to run the Closed Loop Test:

^ Engine running

^ DTC P0117 or P0118 not active

^ IAT Sensor DTCs not active

^ ECT is greater than -40°C

^ IAT is greater than -40°C

^ Start-up ECT is less than 40°C

The following Closed Loop Test passes or tails this diagnostic:

^ For a vehicle with a startup coolant temperature of 40°C (-40°F):

- The total accumulated MAF since start is greater than 9000 grams

- Accumulated idle time is less than 6 minutes

- Minimum stabilized ECT is less than 20°C after 8 minutes

^ For a vehicle with a startup coolant temperature of -7°C (20°F):

- The total accumulated MAF since start is greater than 5500 grams

- Accumulated idle time is less than 4 minutes

- Minimum stabilized ECT is less than 20°C after 5 minutes

^ For a vehicle with a startup coolant temperature of 10°C (50°F):

- The total accumulated MAF since start is greater than 2000 grams

- accumulated idle time is less than 2 minutes

- Minimum stabilized ECT is less than 20°C after 2 minutes

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 OFF the MIL after 3 consecutive driving trips without a fault condition present. A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (the coolant temperature has risen 40°F from the start-up coolant temperature and the engine coolant temperature exceeds 160°F during that same ignition cycle) or the scan tool clearing feature has been used.

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.