U0023

U0023-CAN B BUS (+) CIRCUIT HIGH

U0023 - CAN B Bus (+) Circuit High:

WHEN MONITORED
Continuously

SET CONDITION
The FCM detects the (D55) CAN B Bus (+) circuit is shorted to voltage.

POSSIBLE CAUSES
- (D55) CAN B BUS (+) circuit shorted to voltage
- 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 VOLTAGE

Turn the ignition off.
Disconnect the Front Control Module C1 harness connector.
Turn the ignition on.
Measure the voltage between the (D55) CAN B Bus (+) circuit and ground.

Q: Is voltage above 10.0 volts?

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 VOLTAGE

Measure the voltage between the (D55) CAN B Bus (+) circuit and ground.
While monitoring the voltmeter, disconnect each CAN B Bus module one at a time.

NOTE:
- When performing the above step, turn the ignition off (wait one minute) before disconnecting any module. When the module is disconnected turn the ignition on to check for a short to voltage.
- This is to determine if the short to voltage 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 the voltage above 10.0 volts with all the CAN B Bus modules disconnected?

YES: Repair the (D55) CAN B Bus (+) circuit for a short to voltage. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Replace the module that when disconnected the short to voltage was eliminated,. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test