U1016 Loss of PCM Communication - HVAC

Circuit Description

DTC U1016 will set if the ignition is ON and the HVAC programmer has lost data communication with the PCM.

Diagnosis of this DTC is dependent upon other system symptoms (DTCs) present with U1016.

Test Condition(s)

1. Ignition in ON.

Failure Condition(s)

1. Open circuit.


Action Taken

1. Set DTC U1016.

Troubleshooting Hints

1. Using a scan tool attempt to establish communications with PCM.
2. Check CKT 1807 (PPL) for an open or short to power or ground.
3. Check that PCM is connected to power and ground.
4. If there are multiple Class 2 DTCs current check from a short to ground or voltage in CKT 1807 (PPL).
5. Make sure PCM is operating properly. If the PCM is operating normally replace the HVAC programmer.
6. The PCM loss of HVAC serial data DTC, may be present with this U1016. If so, this would indicate that both the PCM and HVAC programmer were functional when the DTC was set, but they could not communicate with one another. Refer to the diagnostic chart of PCM DTCs for this condition.