SMU - Revised DTC P0128

This bulletin is being issued to revise the Circuit/System Testing section of DTC P0128 in the Engine Controls sub-section of the Service Manual. Please replace the current information in the Service Manual with the following information.

The following information has been updated within SI. If you are using a paper version of this Service Manual, please make a reference to this bulletin on the affected page.

Important: All electrical components and accessories must be turned OFF and allowed to power down.

1. Ignition OFF, disconnect the ECT harness connector at the ECT sensor.
2. Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit terminal B and ground.

- If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, verify the scan tool ECT Sensor parameter is less than -39°C (-38°F).

- If greater than the specified range, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the ECM.

4. Install a 3-amp fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B . Verify the scan tool ECT Sensor parameter is greater than 149°C (300°F).

- If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

5. If all circuits test normal, test or replace the ECT sensor.