Diagnostic Test

1) ECT SENSOR VOLTAGE BELOW 0.078 OF A VOLT
Ignition on, engine not running.

With a scan tool, read the ECT voltage.

Is the voltage below 0.078 of a volt?

Yes
1. Go To 2).
No
1. Refer to INTERMITTENT CONDITION .
2. Perform POWERTRAIN VERIFICATION TEST .
2) ECT SENSOR
Turn the ignition off.

Disconnect the ECT harness connector.

Ignition on, engine not running.

With a scan tool, read ECT voltage.

Is the voltage above 1.0 volt?

Yes
1. Replace the ECT Sensor.
2. Perform POWERTRAIN VERIFICATION TEST .
No
1. Go To 3).
3) (K2) ECT SIGNAL CIRCUIT SHORTED TO THE (K900) SENSOR GROUND CIRCUIT

Fig 1: Checking Engine Coolant Temperature Sensor Signal Circuit & Ground Circuit
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

Disconnect the PCM harness connectors.

Measure the resistance between the (K900) Sensor ground circuit and the (K2) ECT Signal circuit in the ECT Sensor harness connector.

Is the resistance below 5.0 ohms?

Yes
1. Repair the short to between the (K900) Sensor ground circuit and the (K2) ECT Signal circuit.
2. Perform POWERTRAIN VERIFICATION TEST .
No
1. Go To 4).
4) (K2) ECT SIGNAL CIRCUIT SHORTED GROUND

Fig 2: Checking Engine Coolant Temperature Sensor Signal Circuit
Courtesy of DAIMLERCHRYSLER CORP.

Measure the resistance between ground and the (K2) ECT Signal circuit in the ECT Sensor harness connector.

Is the resistance below 100 ohms?

Yes
1. Repair the short to ground in the (K2) ECT Signal circuit.
2. Perform POWERTRAIN VERIFICATION TEST .
No
1. Go To 5).
5) PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.

Were there any problems found?

Yes
1. Repair as necessary.
2. Perform POWERTRAIN VERIFICATION TEST .
No
1. Replace and program the Powertrain Control Module per Service Information.
2. Perform POWERTRAIN VERIFICATION TEST .