Pinpoint Test Y: The Reversing Lamps Are On Continuously
Reversing Lamps
Pinpoint Test Y: The Reversing Lamps Are On Continuously
Refer to Wiring Diagram Set 93, Reversing Lamps for schematic and connector information [1][2]Diagrams By Number.
Normal Operation
When the Body Control Module B (BCM-B) receives a message from the PCM indicating the transmission is in reverse, the BCM-B (Body Control Module B) supplies voltage to the reversing lamps.
Automatic Transmission
The PCM monitors the gear status from the transmission. When the transmission is in REVERSE (R), a message is sent to the BCM-B (Body Control Module B). If any gear status concerns exist, the PCM sets a DTC and the wrench indicator turns on.
Manual Transmission
The PCM sends a voltage signal to the reversing lamps switch. When the transmission is in REVERSE (R), the voltage signal is routed back to the PCM and the PCM sends a message to the BCM-B (Body Control Module B) indicating the transmission is in reverse.
- DTC B1277:15 (Reverse Lamp: Circuit Short To Battery or Open)- sets when the BCM-B (Body Control Module B) detects a short to voltage from one of the reversing lamp output circuits.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Reversing lamp switch (manual transmission)
- BCM-B (Body Control Module B)
- PCM
PINPOINT TEST Y : 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.
Y1 CHECK FOR BCM-B (Body Control Module B) DTC B1272:15
- Ignition OFF.
- Review the results from the BCM-B (Body Control Module B) self-test.
Is DTC B1272:15 present?
Yes
GO to Y2.
No
GO to Y3.
Y2 CHECK THE BCM-B (Body Control Module B) REVERSING LAMP OUTPUT CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: BCM-B (Body Control Module B) C4368A.
- Ignition ON.
Do the reversing lamps continue to illuminate?
Yes
REPAIR circuit CLS10 (GN/BN) (LH reverse lamp) or circuit CLS11 (GY/VT) (RH reverse lamp) for a short to voltage. CLEAR the DTCs. REPEAT the self-test.
No
GO to Y6.
Y3 CHECK FOR PCM DTCs
- Ignition ON.
- Disconnect: PCM Self-Test.
- Carry out the PCM Key ON Engine OFF (KOEO) and Key ON Engine Running (KOER) self-tests.
Are any PCM DTCs present?
Yes
REFER to Body Control Systems or Computers and Control Systems Information as necessary.
No
For vehicles with an automatic transmission, REFER to Automatic Transmission/Transaxle &/or Transmission Control Systems to diagnose a Transmission Range (TR) input concern.
For vehicles with a manual transmission, GO to Y4.
Y4 CHECK THE REVERSING LAMP SWITCH
- Ignition OFF.
- Disconnect: Reversing Lamp Switch C169 (3.7L or 5.0L engine) or C1131 (5.4L engine).
- Ignition ON.
Do the reversing lamps continue to illuminate?
Yes
GO to Y5.
No
INSTALL a new reversing lamp switch. REFER to Reversing Lamp Switch . TEST the system for normal operation.
Y5 CHECK THE REVERSING LAMP SWITCH INPUT CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: PCM C1381T (3.7L engine) or C175T (5.0L or 5.4L engine).
- For vehicles with a 3.7L or 5.0L engine, measure the resistance between the reversing lamp switch C169-1, circuit CET47 (BU), harness side and ground.
- For vehicles with a 5.4L engine, measure the resistance between the reversing lamp switch C1131-A, circuit CET47 (BU), harness side and ground.
Is the resistance greater than 10,000 ohms?
Yes
GO to Y7.
No
REPAIR circuit CET47 (BU) for a short to ground. TEST the system for normal operation.
Y6 CHECK FOR CORRECT BCM-B (Body Control Module B) OPERATION
- Disconnect all the BCM-B (Body Control Module B) connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the BCM-B (Body Control Module B) 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-B (Body Control Module B). 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. CLEAR the DTCs. REPEAT the self-test.
Y7 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.