U0019-CAN B BUS
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 PLGM 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 chaffed, 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 - DIAGNOSIS AND TESTING)
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 Power Liftgate Module C2 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 Power Liftgate Module C2 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 - DIAGNOSIS AND TESTING)
4. CHECK (D54) CAN B BUS (–) CIRCUIT FOR A SHORT TO THE (D55) CAN B BUS (+) CIRCUIT
Measure the resistance between the (D54) CAN B Bus (–) circuit and the (D55) CAN B Bus (+) circuit in the Power Liftgate Module C2 harness connector.
Is the resistance below 2.0 ohms?
Yes
- Repair the (D54) CAN B Bus (–) circuit for a short to the (D55) CAN B Bus (+) circuit.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - DIAGNOSIS AND TESTING)
No
- Go To 5
5. 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 Power Liftgate Module C2 connector.
Is the resistance below 2.0 ohms?
Yes
- Replace the Power Liftgate Module in accordance with the Service Information.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - DIAGNOSIS AND TESTING)
No
- Repair the (D54) CAN B Bus (–) circuit for an open.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - DIAGNOSIS AND TESTING)
6. CHECK THE (D54) CAN B BUS (–) CIRCUIT FOR A SHORT TO VOLTAGE
Turn the ignition on.
Measure the voltage of the (D54) CAN B Bus (–) circuit.
Is there any voltage present?
Yes
- Repair the (D54) CAN B Bus (–) circuit for a short to voltage.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - DIAGNOSIS AND TESTING)
No
- Go To 7
7. CHECK THE (D55) CAN B BUS (+) CIRCUIT FOR A SHORT TO VOLTAGE
Turn the ignition on.
Measure the voltage of the (D55) CAN B Bus (+) circuit.
Is there any voltage present?
Yes
- Repair the (D55) CAN B Bus (+) circuit for a short to voltage.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - DIAGNOSIS AND TESTING)
No
- Go To 8
8. CHECK THE (D54) CAN B BUS (–) CIRCUIT FOR A SHORT TO GROUND
Turn the ignition off.
Measure the resistance between ground and the (D54) CAN B Bus (–) circuit.
Is the resistance below 100 ohms?
Yes
- Repair the (D54) CAN B Bus (–) circuit for a short to ground.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - DIAGNOSIS AND TESTING)
No
- Go To 9
9. CHECK THE (D55) CAN B BUS (+) CIRCUIT FOR A SHORT TO VOLTAGE
Turn the ignition off.
Measure the resistance between ground and the (D55) CAN B Bus (+) circuit.
Is the resistance below 100 ohms?
Yes
- Repair the (D55) CAN B Bus (+) circuit for a short to ground.
- Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - DIAGNOSIS AND TESTING)
No
- Replace the Power Liftgate Module in accordance with the service information.
- Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - DIAGNOSIS AND TESTING)