U1016 Loss of PCM Serial Communication - HVAC

CIRCUIT DESCRIPTION
DTC U1016 will set if the ignition is ON and the Air Conditioning Programmer (ACM) 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.

TROUBLE SHOOTING HINTS
1. Using a scan tool attempt to establish communications with PCM.
2. Check CKT 1807 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 for a short to ground or voltage in CKT 1807.
5. Make sure PCM is operating properly, refer to PCM diagnostic system check. If the PCM is operating normally replace the ACM.
6. DTC P1605, PCM loss of HVAC serial data, may be present with this DTC. If so, this would indicate that both the PCM and ACM were functional when the DTC was set, but they could not communicate with one another. Refer to the diagnostic chart of PCM DTCs.