Communications

U0001-CAN C BUS





For a complete wiring diagram Refer to Diagrams/Electrical.

- When Monitored:

With the ignition on.

- Set Condition:

The FCM detects a short in either CAN C Bus circuit.





Diagnostic Test

1.TEST FOR INTERMITTENT CONDITION

Turn the ignition on.

With the scan tool, record and erase FCM DTC's.

Cycle the ignition from on to off 3 times.

Turn the ignition on.

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

Does the scan tool display U0001-CAN C BUS as active?

Yes

- Go To 2

No

- The conditions that caused this code to set are not present at this time. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.

2.ANTILOCK BRAKE MODULE - INTERNAL SHORT

Turn the ignition off.

Disconnect the Antilock Brake Module harness connector.

Turn the ignition on.

With the scan tool, record and erase FCM DTC's.

Cycle the ignition from on to off 3 times.

Turn the ignition on.

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

Does the scan tool display U0001-CAN C BUS as active?

Yes

- Go To 3

No

- Inspect the wiring and connectors for damage or shorted circuits. If ok, replace the Antilock Brake Module.
- Perform ABS VERIFICATION TEST - VER 1. ABS Verification Test

3.POWERTRAIN CONTROL MODULE - INTERNAL SHORT

Turn the ignition off.

Disconnect the Powertrain Control Module C1 harness connector.

Turn the ignition on.

With the scan tool, record and erase FCM DTC's.

Cycle the ignition from on to off 3 times.

Turn the ignition on.

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

Does the scan tool display U0001-CAN C BUS as active?

Yes, with Floor Shift

- Go To 4

Yes, with Column Shift

- Go To 5

No

- Inspect the wiring and connectors for damage or shorted circuits. If ok, replace and program the Powertrain Control Module.
- Perform (NGC) POWERTRAIN VERIFICATION TEST VER - 5. NGC Powertrain Verification Test Ver - 5

4.SHIFTER LEVER ASSEMBLY (NAG1 ONLY)- INTERNAL SHORT

Turn the ignition off.

NOTE: If the vehicle is not equipped with a NAG1 controller then skip this step.

Disconnect the Shifter Lever Assembly harness connector.

Turn the ignition on.

With the scan tool, record and erase FCM DTC's.

Cycle the ignition from on to off 3 times.

Turn the ignition on.

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

Does the scan tool display U0001-CAN C BUS as active?

Yes

- Go To 6

No

- Inspect the wiring and connectors for damage or shorted circuits. If ok, replace and program the Shifter Lever Assembly.
- Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1. NAG1 Transmission Verification Test

5.ELECTRONIC SHIFT MODULE (COLUMN NAG1)- INTERNAL SHORT

Turn the ignition off.

NOTE: If the vehicle is not equipped with a NAG1 controller then skip this step.

Disconnect the Electronic Shift Module harness connector.

Turn the ignition on.

With the scan tool, record and erase FCM DTC's.

Cycle the ignition from on to off 3 times.

Turn the ignition on.

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

Does the scan tool display U0001-CAN C BUS as active?

Yes

- Go To 6

No

- Inspect the wiring and connectors for damage or shorted circuits. If ok, replace and program the Electronic Shift Module.
- Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1. NAG1 Transmission Verification Test

6.TRANSMISSION CONTROL MODULE (NAG1 ONLY)- INTERNAL SHORT

Turn the ignition off.

NOTE: If the vehicle is not equipped with a NAG1 controller then skip this step.

Disconnect the Transmission Control Module C2 harness connector.

Turn the ignition on.

With the scan tool, record and erase FCM DTC's.

Cycle the ignition from on to off 3 times.

Turn the ignition on.

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

Does the scan tool display U0001-CAN C BUS as active?

Yes

- Go To 7

No

- Inspect the wiring and connectors for damage or shorted circuits. If ok, replace and program the Transmission Control Module.
- Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1. NAG1 Transmission Verification Test

7.ENGINE CONTROL MODULE (DIESEL)- INTERNAL SHORT

Turn the ignition off.

Disconnect the Engine Control Module C2 harness connector.

Turn the ignition on.

With the scan tool, record and erase FCM DTC's.

Cycle the ignition from on to off 3 times.

Turn the ignition on.

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

Does the scan tool display U0001-CAN C BUS as active?

Yes

- Go To 8

No

- Inspect the wiring and connectors for damage or shorted circuits. If ok, replace and program the Engine Control Module.
- Perform the ECM VERIFICATION TEST. PCM Verification Test

8.STEERING CONTROL MODULE - INTERNAL SHORT

Turn the ignition off.

Remove the Steering Control Module.

Turn the ignition on.

With the scan tool, record and erase FCM DTC's.

Cycle the ignition from on to off 3 times.

Turn the ignition on.

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

Does the scan tool display U0001-CAN C BUS as active?

Yes

- Go To 9

No

- Inspect the wiring and connectors for damage or shorted circuits. If ok, replace and program the Steering Control Module.
- Perform the BODY VERIFICATION TEST - VER 1. Body Verification Test

9.(D65) CAN C BUS (+) CIRCUIT SHORTED TO VOLTAGE





Turn the ignition off.

Disconnect the Front Control Module C1 harness connector.

Turn the ignition on.

Measure the voltage between the (D65) CAN C Bus (+) circuit and ground.

Is there any voltage present?

Yes

- Repair the (D65) CAN C Bus (+) circuit for a short to voltage.
- Perform the BODY VERIFICATION TEST - VER 1. Body Verification Test

No

- Go To 10

10.(D64) CAN C BUS (-) CIRCUIT SHORTED TO VOLTAGE





Measure the voltage between the (D64) CAN C Bus (-) circuit and ground.

Is there any voltage present?

Yes

- Repair the (D64) CAN C Bus (-) circuit for a short to voltage.
- Perform the BODY VERIFICATION TEST - VER 1. Body Verification Test

No

- Go To 11

11.(D65) CAN C BUS (+) CIRCUIT SHORTED TO GROUND





Turn the ignition off.

Measure the resistance between ground and the (D65) CAN C Bus (+) circuit.

Is any resistance present?

Yes

- Repair the (D65) CAN C Bus (+) circuit for a short to ground.
- Perform the BODY VERIFICATION TEST - VER 1. Body Verification Test

No

- Go To 12

12.(D64) CAN C BUS (-) CIRCUIT SHORTED TO GROUND





Measure the resistance between ground and the (D64) CAN C Bus (-) circuit.

Is any resistance present?

Yes

- Repair the (D64) CAN C Bus (-) circuit for a short to ground.
- Perform the BODY VERIFICATION TEST - VER 1. Body Verification Test

No

- Go To 13

13.(D65) CAN C BUS (+) CIRCUIT SHORTED TO (D64) CAN C BUS (-) CIRCUIT





Measure the resistance between the (D65) CAN C Bus (+) circuit and the (D64) CAN C Bus (-) circuit.

Is any resistance present?

Yes

- Repair the (D65) CAN C Bus (+) circuit for a short to the (D64) CAN C Bus (-) circuit.
- Perform the BODY VERIFICATION TEST - VER 1. Body Verification Test

No

- Inspect the wiring and connectors for damage or shorted circuits. If ok, replace and program the Front Control Module.
- Perform the BODY VERIFICATION TEST - VER 1. Body Verification Test