Pinpoint Test W: The Reversing Lamps Are On Continuously
Reversing Lamps
Pinpoint Test W: The Reversing Lamps Are On Continuously
Normal Operation
The PCM (gasoline engine) or the Transmission Control Module (TCM) (diesel engine) monitors the transmission. When the transmission is in REVERSE, the PCM or Transmission Control Module (TCM) 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 (Body Control Module) receives the message indicating the transmission is in REVERSE, the BCM (Body Control Module) provides voltage to the reversing lamps.
On vehicles with a manual transmission, the reversing lamp switch is monitored by the PCM.
- DTC B1277:15 (Reverse Lamp: Circuit Short To Battery or Open)- a DTC that sets when the BCM (Body Control Module) detects a short to voltage from the reversing lamp output circuit.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Reversing lamp switch
- BCM (Body Control Module)
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 (Body Control Module) CONTROL OF THE REVERSING LAMPS
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: BCM (Body Control Module) DataLogger.
- Select the BCM (Body Control Module) reverse lamps active command (RVRS_LMPS). Command the reverse lamps off.
Do the reversing lamps turn off?
Yes
If equipped with an automatic transmission, Automatic Transmission/Transaxle &/or Transmission Control Systems to diagnose a Transmission Range (TR) concern.
If equipped with a manual transmission, GO to W3.
No
GO to W2.
W2 CHECK THE BCM (Body Control Module) OUTPUT
- Ignition OFF.
- Disconnect: BCM (Body Control Module) 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 W6.
W3 CHECK THE REVERSING LAMP SWITCH
- Ignition OFF.
- Disconnect: Reversing Lamp Switch C169.
- Ignition ON.
Do the reversing lamps continue to illuminate?
Yes
GO to W4.
No
INSTALL a new reversing lamp switch. TEST the system for normal operation.
W4 CHECK THE REVERSING LAMP SWITCH INPUT CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: PCM C175T.
- Ignition ON.
- Measure the resistance between the PCM C175T-7, circuit CET47 (GY/OG or BU), harness side and ground.
Is the resistance greater than 10,000 ohms?
Yes
GO to W5.
No
REPAIR circuit CET47 (GY/OG or BU) for a short to ground. TEST the system for normal operation.
W5 CHECK FOR CORRECT PCM OPERATION
- Disconnect all the PCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the PCM 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 PCM. 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.
W6 CHECK FOR CORRECT BCM (Body Control Module) OPERATION
- Disconnect all the BCM (Body Control Module) connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the BCM (Body Control Module) 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 (Body Control Module). 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.