HVAC
U0019-CAN B BUS (ATC)
For a complete wiring diagram Refer to Diagrams/Electrical.
- When Monitored:
Continuously
- Set Condition:
If the CAN B Bus (+) or CAN B Bus (-) circuit is open, shorted to voltage, or shorted to ground.
Diagnostic Test
1.VERIFY DTC U0019-CAN B BUS IS ACTIVE
Turn the ignition on.
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 BODY VERIFICATION TEST - VER 1. Body Verification Test
2.CHECK FOR ACTIVE CAN B BUS RELATED DTCS IN THE FRONT CONTROL MODULE (FCM)
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).
No
- Go To 3
3.CHECK (D55) CAN B BUS (+) CIRCUIT FOR AN OPEN
Turn the ignition off.
Disconnect the negative battery cable.
Disconnect the A/C Heater Control C1 harness connector.
Disconnect the Front Control Module (FCM) C1 harness connector.
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 BODY VERIFICATION TEST - VER 1. Body Verification Test
4.CHECK (D54) CAN B BUS (-) CIRCUIT FOR AN OPEN
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 BODY VERIFICATION TEST - VER 1. Body Verification Test
No
- Repair the (D54) CAN B Bus (-) circuit for an open.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test