U0019-CAN B BUS (ATC)
For a complete wiring diagram Refer to Section 8W.
- When Monitored:
Continuously
- Set Condition:
If the CAN B Bus (+) or CAN B Bus (-) circuit is open, shorted to voltage, or shorted to ground.
| Possible Causes |
| ACTIVE U0019 CAN B BUS DTC IN FRONT CONTROL MODULE |
| (D55) CAN B BUS (+) CIRCUIT OPEN |
| (D54) CAN B BUS (-) CIRCUIT OPEN |
| A/C HEATER CONTROL |
Diagnostic Test
1. VERIFY DTC U0019–CAN B BUS IS ACTIVETurn 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. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
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). (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - DIAGNOSIS AND TESTING).
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. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
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 in accordance with the Service Information.
- Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).
No
- Repair the (D54) CAN B Bus (–) circuit for an open.
- Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).