B21F7

B21F7-11-ELECTRONIC SHIFTER POWER SUPPLY - CIRCUIT SHORT TO GROUND

For a complete wiring diagram, refer to the Wiring Information.

- When Monitored:
With the Unlock Run-Start output commanded on.

- Set Condition:
The Body Control Module (BCM) has detected a low condition on the (F1) Ignition Unlock-Run-Start Output circuit.





1. INTERMITTENT CONDITION
1. Turn the ignition on.
2. With the scan tool, clear all DTCs.
3. With the scan tool, read DTCs.

Does the scan tool display DTC: B21F7-11-ELECTRONIC SHIFTER POWER SUPPLY - CIRCUIT SHORT TO GROUND?

Yes

- For a NAG1 transmission, Go To 2
- For a 8HP45 transmission, Go To 3

No

- Test complete, the condition or conditions that originally set this DTC are not present at this time. Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals, and correct pin tension.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

2. CHECK THE SHIFT LEVEL ASSEMBLY FOR A CONCERN
1. Turn the ignition off.
2. Disconnect the Shift Lever Assembly C1 harness connector.
3. Turn the ignition on.
4. With the scan tool, read DTCs.

Does the scan tool display DTC: B21F7-11-ELECTRONIC SHIFTER POWER SUPPLY - CIRCUIT SHORT TO GROUND?

Yes

- Replace the ESM, which is integral to the Shift Lever Assembly,. Transmission Shifter - Removal
- Perform the NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test.

No

- Go To 4

3. CHECK THE TCM FOR A CONCERN
1. Turn the ignition off.
2. Disconnect the TCM C1 harness connector.
3. Turn the ignition on.
4. With the scan tool, read DTCs.

Does the scan tool display DTC: B21F7-11-ELECTRONIC SHIFTER POWER SUPPLY - CIRCUIT SHORT TO GROUND?

Yes

- Replace the TCM. Transmission Control Module - Description
- Perform the TRANSMISSION VERIFICATION TEST. Verification Tests.

No

- Go To 4

4. CHECK THE (F1) IGNITION UNLOCK-RUN-START OUTPUT CIRCUIT FOR A SHORT TO GROUND
1. Turn the ignition off.
2. Disconnect the BCM E harness connector.
3. Measure the resistance between ground and the (F1) Ignition Unlock-Run-Start Output circuit.

Is the resistance above 10k Ohms?

Yes

- Replace the Body Control Module (BCM). Body Control Module - Removal.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Repair the short to ground in the (F1) Ignition Unlock-Run-Start Output circuit.
- Perform the BODY VERIFICATION TEST. Body Verification Test.