HVAC, ATC

U0019-CAN B BUS





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

- When Monitored:
Continuously

- Set Condition:
If the CAN B Bus (+) or CAN B Bus (-) circuit is open, shorted to voltage, or shorted to ground.





1. VERIFY DTC U0019-CAN B BUS IS ACTIVE
1. Turn the ignition on.
2. With the scan tool, read HVAC DTCs.

Does the scan tool display active: U0019-CAN B BUS?

Yes

- Go To 2

No

- If the DTC is stored, check for an intermittent condition by inspecting the related wiring harness for chafed, pierced, pinched, and partially broken wires. Also, inspect the related connectors for broken, bent, pushed out, spread, corroded, or contaminated terminals.
- Perform the BODY VERIFICATION TEST Body Verification Test.

2. CHECK FOR ACTIVE CAN B BUS RELATED DTCS IN THE FRONT CONTROL MODULE (FCM)
1. With the scan tool, read Front Control Module (FCM) DTCs

Does the scan tool display any active CAN B BUS related DTCs?

Yes

- Diagnose and repair the DTC(s). Testing and Inspection.

No

- Go To 3

3. CHECK (D55) CAN B BUS (+) CIRCUIT FOR AN OPEN




1. Turn the ignition off.
2. Disconnect the negative battery cable.
3. Disconnect the A/C Heater Control C1 harness connector.
4. Disconnect the Front Control Module (FCM) C1 harness connector.
5. Measure the resistance of the (D55) CAN B Bus (+) circuit between the Front Control Module C1 harness connector and the A/C Heater Control C1 harness connector.

Is the resistance below 2.0 ohms?

Yes

- Go To 4

No

- Repair the (D55) CAN B Bus (+) circuit for an open.
- Perform the BODY VERIFICATION TEST Body Verification Test.

4. CHECK (D54) CAN B BUS (-) CIRCUIT FOR AN OPEN




1. Measure the resistance of the (D54) CAN B Bus (-) circuit between the Front Control Module C1 connector and the A/C Heater Control C1 harness connector.

Is the resistance below 2.0 ohms?

Yes

- Replace the A/C Heater Control.
- Perform the BODY VERIFICATION TEST Body Verification Test.

No

- Repair the (D54) CAN B Bus (-) circuit for an open.
- Perform the BODY VERIFICATION TEST Body Verification Test.