Diagnostic Test

1) CHECK FOR ACTIVE DTC's
With the scan tool, read the active DTC's.

Cycle the ignition switch from off to on at least 5 times, leaving the ignition on for a minimum of 90 seconds per cycle.

With the scan tool, read the active DTC's.

Does the scan tool display this DTC as active?

Yes
1. Go To 2).
No
1. If the DTC is stored, check for an intermittent condition. Visually inspect the related wiring harness connectors. Look for broken, bent, pushed out, or corroded terminals.
2) CHECK FRONT CONTROL MODULE DTC's
With the scan tool, read Front Control Module active DTC's

Does the scan tool display any CAN B BUS DTC's - ACTIVE?

Yes
1. Refer to (ELECTRICAL/ELECTRONIC CONTROL MODULES - DIAGNOSIS AND TESTING) .
No
1. Go To 3).
3) (D55) CAN B BUS (+) CIRCUIT OPEN
Turn the ignition off.

Disconnect the negative battery cable.

Disconnect the SKREEM connector.

Disconnect the Front Control Module connector.

Measure the resistance of the (D55) CAN B Bus (+) circuit between the Front Control Module harness connector and the SKREEM harness connector.

Is the resistance below 2.0 ohms?

Yes
1. Go To 4).
No
1. Repair the (D55) CAN B Bus (+) circuit for an open.
2. Perform BODY VERIFICATION TEST - VER 1. (Refer to ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE - BODY VERIFICATION TEST - VER 1) .
4) (D54) CAN B BUS (-) CIRCUIT OPEN
Measure the resistance of the (D54) CAN B Bus (-) circuit between the Front Control Module harness connector and the SKREEM harness connector.

Is the resistance below 2.0 ohms?

Yes
1. Replace the SKREEM (Refer to STANDARD PROCEDURE - PCM/ECM/SKREEM PROGRAMMING) .
2. Perform BODY VERIFICATION TEST - VER 1. (Refer to ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE - BODY VERIFICATION TEST - VER 1) .
No
1. Repair the (D54) CAN B Bus (-) circuit for an open.
2. Perform BODY VERIFICATION TEST - VER 1. (Refer to ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE - BODY VERIFICATION TEST - VER 1) .