U0022
U0022-CAN B BUS (+) CIRCUIT LOWU0022 - CAN B Bus (+) Circuit Low:
WHEN MONITORED
Continuously.
SET CONDITION
The FCM detects the (D55) CAN B Bus (+) circuit is shorted to ground.
POSSIBLE CAUSES
- (D55) CAN B BUS (+) circuit shorted to ground
- Any CAN B bus module
- Front control module
Diagnostic Test
1. TEST FOR INTERMITTENT CONDITION
Turn the ignition on.
With the scan tool, record and erase FCM DTC's.
Cycle the ignition from on to off 3 times.
Turn the ignition on.
With the scan tool, read active FCM DTC's.
Q: Does the scan tool display this DTC as active?
YES: Go To 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.
2. CHECK THE (D55) CAN B BUS (+) CIRCUIT FOR A SHORT TO GROUND
Turn the ignition off.
Disconnect the Front Control Module C1 harness connector.
Measure the resistance between ground and the (D55) CAN B Bus (+) circuit.
Q: Is resistance below 1000.0 ohms?
YES: Go To 3
NO: Inspect the wiring and connectors for damage or shorted circuits. If ok, replace the Front Control Module. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
3. (D55) CAN B BUS (+) CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (D55) CAN B Bus (+) circuit.
While monitoring the ohmmeter, disconnect each CAN B Bus module one at a time.
NOTE:
- This is to determine if the short to ground is internal within a module or if the circuit is shorted.
- Disconnecting an in-line connector can eliminate a module or group of modules from the list of possible causes for this fault. Refer to the wiring diagrams to assist in diagnosis.
Q: Is resistance below 1000.0 ohms with all the CAN B Bus modules disconnected?
YES: Repair the (D55) CAN B Bus (+) circuit for a short to ground. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Replace the module that when disconnected the short to ground was eliminated,. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test