U0001-CAN C Bus circuit

U0001 code - The Controller Area Network (CAN) Bus is a serial two wire bus communication system for transferring data between control modules. The CAN Bus types a vehicle may have one or more types of CAN Bus. CAN B is a medium-speed bus, which operates at 83.3 kbps. CAN C is a high-speed bus which operates at 500 kbps.

DTC U0001-CAN C bus circuit

A second high-speed bus, diagnostic CAN C, is designed to communicate with a diagnostic tool. The newest version of CAN is interior High Speed CAN (or IHS), which will operate at 125 kbps, and will appear on vehicles in the future. CAN B is event-driven, opening a door will awaken most modules on the bus. Up to 32 modules are permitted, interior High Speed CAN will be event-driven, and will use CAN C modules with reduced clock speed.

Set condition:
  • The Totally Intagrated Power Module (TIPM) or Body Control Module (BCM) detects a corrupt CAN C bus message.
Possible causes:
  • CAN C bus (+) circuit shorted to ground.
  • CAN C bus (-) circuit shorted to voltage.
  • CAN C bus (+) circuit shorted to CAN C bus (-) circuit.
  • Antilock Brake System (ABS) Module.
  • Powertrain Control Module (PCM).
  • Electric gear Shift Module (ESM).
  • Transmission Control Module (TCM).
  • Steering Angle Sensor (SAS).
  • Automatic Sway Bar System Module (If equipped).
  • Wireless Control Module (WCM).
  • Occupant Restraint Controller (ORC or Airbag Module).
  • Totally Integrated Power Module (TIPM) /Body Control Module (BCM).


Diagnose U0001-CAN C Bus circuit


Step 1. Test for intermittent condition
Turn the ignition on, using the scan tool, record and erase TIPM/BCM DTC. Cycle the ignition on to off three times, turn the ignition on, using the scan tool read active DTC.

Does the scan tool display this DTC as active ?

Yes, go to step 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.

Step 2. Antilock Brake System (ABS) Module - Internal short
Turn the ignition off, disconnect the ABS Module harness connector. Turn the ignition on, using the scan tool, record and erase DTC. Cycle the ignition from on to off three times, turn the ignition on, using the scan tool read active DTC.

Does the scan tool display this DTC is active ?

Yes, go to step 3.
No, inspect the wiring and connectors for damage or shorted circuits. If OK, replace ABS Module, perform the ABS Verification Test.

Step 3. Powertrain Control Module (PCM) - Internal short
Turn the ignition off, disconnect the PCM harness connector. Turn the ignition on, using the scan tool, record and erase DTC. Cycle the ignition from on to off three times, turn the ignition on, using the scan tool read active DTC.

Does the scan tool display this DTC is active ?

Yes, go to step 4.
No, inspect the wiring and connectors for damage or shorted circuits. If OK, replace and program the Powertraint Control Module (PCM). Perform the Powertrain Verification Test.

Step 4. Transmission Control Module (TCM) - Internal short
Turn the ignition off. If vehicle is not equipped wuth this module, answer yes to the question.
Disconnect the TCM harness connector, turn the ignition on, using the scan tool and erase DTC. Cycle the ignition from on to off three times, turn the ignition on, using the scan tool, read active DTC.

Does the scan tool display this DTC as active ?

Yes, go to step 5.
No, inspect the wiring and connectors for damage or shorted circuits. If OK, replace and program the TCM.

Step 5. Steering Angle Sensor (SAS) - Internal short
Turn the ignition off. If vehicle is not equipped with this module, answer yes to the question.
Disconnect the SAS harnes connector, turn the ignition on, using the scan tool and erase DTC. Cycle the ignition from on to off three times, turn the ignition on, using the scan tool, read active DTC.

Does the scan tool display this DTC as active ?

Yes, go to step 6.
No, inspect the wiring and connectors for damage or shorted circuits. If OK, replace the Steering Angle Sensor.

Step 6. Automatic Sway Bar System Module - Internal short
Turn the ignition off. If vehicle is not equipped with this module, answer yes to the question.
Disconnect the Sway Bar Module harness connector, turn the ignition on, using the scan tool, erase DTC. Cycle the ignition from on to off three times, turn the ignition on, using the scan tool read active DTC.

Does the scan tool display this DTC as active ?

Yes, go to step 7.
No, inspect the wiring and connectors for damage or shorted circuits. If OK, replace the Sway Bar Module.

Step 7. Electric gear Shift Module (ESM) - Internal short
Turn the ignition off. If vehicle is not equipped with this module, answer yes to the question.
Disconnect the Electric gear Shift Module harness connector, turn the ignition on, with the scan tool, erase DTC. Cycle the ignition from on to off three times, turn the ignition on, with the scan tool read active DTC.

Does the scan tool display this DTC as active ?

Yes, go to step 8.
No, inspect the wiring and connectors for damage or shorted circuits. If OK, replace the Automatic Sway Bar Module.

Step 8. Wireless Control Module (WCM) - Internal short
Turn the ignition off, disconnect the WCM harness connector. Turn the ignition on, using the scan tool erase DTC. Cycle the ignition from on to off three seconds, turn the ignition on, using the scan tool read active DTC.

Does the scan tool display this DTC as active ?

Yes, go to step 9.
No, inspect the wiring and connectors for damage or shorted circuits. If OK, replace the WCM.

Step 9. Occupant Restraint Controller (ORC or Airbag Module) - Internal short
Turn the ignition off.
Turn the ignition off disconnect the 12 Volt battery and wait two minutes before proceeding. Failure to follow these instructions may result in possible serious or fatal injury.
Disconnect the ORC harness connector.
Turn the ignition on, then reconnect the 12 Volt battery and wait two minutes before proceeding. Failure to follow these instructions may result in possible serious or fatal injury.
Using the scan tool erase DTC, cycle ignition from on to off three times. Turn the ignition on, using the scan tool read active DTC.

Does the scan tool display this DTC as active ?

Yes, go to step 10.
No, inspect the wiring and connectors for damage or shorted circuits. If OK, replace the ORC or Airbag Module. Perform the Airbag system verification.

Step 10. Check the CAN C Bus (-) circuit for a short to voltage
Measure the voltage between the CAN C Bus (-) circuit and ground.

Is there any voltage present ?

Yes, repair the short to voltage in the CAN C Bus (-) circuit.
No, go to step 11.

Step 11. Check the CAN C Bus (+) circuit for a short to ground
Turn the ignition off, measure the resistance between ground and the CAN C Bus (+) cirucit.

Is any resistance present ?

Yes, repair the short to ground in the CAN C Bus (+) circuit.
No, go to step 12.

Step 12. Check the CAN C Bus (+) circuit for a short to CAN C Bus (-) circuit
Measure the resistance between the CAN C Bus (+) circuit and the CAN C Bus (-) circuit.

Is any resistance present ?

Yes, repair the short between the CAN C Bus (+) circuit and the CAN C Bus (-) circuit.
No, inspect the wiring and connectors for damage or shorted circuits. If OK, replace and program the Totally Integrated Power Module (TIPM) or Body Control Module (BCM).

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