U0021

U0021-CAN B BUS (+) CIRCUIT OPEN

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

- When Monitored:
Ignition on

Battery voltage between 10 and 16 volts

- Set Condition:
The Totally Integrated Power Module (TIPM) detects the (D55) CAN B Bus (+) circuit is open.





1. TEST FOR INTERMITTENT CONDITION

NOTE: Check for any Technical Service Bulletins (TSBs) related to the condition. If a TSB applies, perform the procedure outlined in the TSB before continuing.

1. Turn the ignition on.
2. With the scan tool, record and erase TIPM DTCs.
3. Cycle the ignition from on to off three times.
4. Turn the ignition on.
5. With the scan tool, read active TIPM DTCs.

Does the scan tool display this DTC 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. ATTEMPT TO ISOLATE THE OPEN CONDITION




1. Turn the ignition on.
2. With the scan tool, select ECU View.
3. Verify that all CAN B Bus modules are communicating with the scan tool.

NOTE: If any module is not communicating, perform the appropriate no response test procedure before proceeding.

4. Turn the ignition off.
5. Gain access to the Totally Integrated Power Module C3 harness connector, but do not disconnect.
6. Using a fused jumper wire, connect one end to ground and with the other end backprobe the CAN B Bus (-) circuit at the TIPM C3 harness connector.
7. Turn the ignition on.
8. With the scan tool monitor the ECU View screen and document all the modules that are not communicating.

Are there any CAN B Bus modules not communicating?

Yes

- Go To 3

No

- Check backprobe connection to ground, make sure it is proper. The CAN B Bus open DTC may no longer be active, it may be stored. Check all module connections.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

3. ATTEMPT TO ISOLATE THE OPEN CONDITION - MULTIPLE MODULES
1. With the scan tool continue monitoring the ECU View screen.

Are there multiple CAN B Bus modules not communicating?

Yes

- The most likely cause of this condition is an open CAN B Bus (+) circuit between a common CAN B Bus splice and the modules. Use the wiring diagrams to help you determine where the open condition exists.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Go To 4

4. (D55) CAN B BUS (+) CIRCUIT OPEN




1. Turn the ignition off.
2. Disconnect the module that is not communicating.
3. Turn the ignition on.
4. Measure the voltage between the (D55) CAN B Bus (+) circuit and ground.

Is there any voltage present?

Yes

- Inspect the connector and terminal for damage, inspect for spread terminals, or pushed out terminals. If OK, replace the module.
- Perform the appropriate verification test for the module being replaced. If there is no verification test for the associated module perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Repair the (D55) CAN B Bus (+) circuit for an open between the next common splice and the module. Use the wiring diagrams to help you determine where the open condition exists.
- Perform the BODY VERIFICATION TEST. Body Verification Test.