Pinpoint Test W: The Reversing Lamps Are On Continuously

Reversing Lamps

Pinpoint Tests

Pinpoint Test W: The Reversing Lamps Are On Continuously

Refer to Wiring Diagram Set 93, Reversing Lamps for schematic and connector information. Diagrams By Number

Normal Operation

The PCM monitors the transmission gear status. When the transmission is in reverse, the PCM sends a message to the Body Control Module (BCM) over the High Speed Controller Area Network (HS-CAN), indicating the transmission is in reverse. When the BCM receives the message indicating the transmission is in reverse and the ignition is in RUN, the BCM provides voltage to the reversing lamps and the auto-dimming interior mirror.

- DTC B1277:15 (Reverse Lamp: Circuit Short To Battery or Open) - This DTC sets when the BCM detects a short to voltage from the reversing lamp output circuit.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors
- Auto-dimming interior mirror
- Transmission gear input
- BCM

PINPOINT TEST W: THE REVERSING LAMPS ARE ON CONTINUOUSLY

NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

-------------------------------------------------
W1 CHECK THE BCM CONTROL OF THE REVERSING LAMPS

- Ignition ON.
- Enter the following diagnostic mode on the scan tool: BCM DataLogger.
- Select the BCM reverse lamps active command (RVRS_LMPS). Command the reverse lamps off.
- Do the reversing lamps turn off?

Yes
REFER to Automatic Transaxle/Transmission - 6R80 Testing and Inspection to diagnose a Transmission Range (TR) concern.

No
GO to W2.

-------------------------------------------------
W2 CHECK THE BCM OUTPUT

- Ignition OFF.
- Disconnect: BCM C2280D.
- Ignition ON.
- Do the reversing lamps continue to illuminate?

Yes
REPAIR circuit CLS28 (BU/WH) for a short to voltage. TEST the system for normal operation.

No
GO to W3.

-------------------------------------------------
W3 CHECK FOR CORRECT BCM OPERATION

- Disconnect all the BCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the BCM connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?

Yes
INSTALL a new BCM. REFER to Multifunction Electronic Modules Service and Repair. TEST the system for normal operation.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.

-------------------------------------------------