Pinpoint Test Y: The Reversing Lamps Are On Continuously
Reversing Lamps
Pinpoint Tests
Pinpoint Test Y: The Reversing Lamps Are On Continuously
Refer to Wiring Diagram Set 93, Reversing Lamps for schematic and connector information. 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 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. 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 indicating the transmission is in reverse.
- DTC B1277:15 (Reverse Lamp: Circuit Short To Battery or Open) - sets when the BCM-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
- 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.
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Y1 CHECK FOR BCM-B DTC B1272:15
- Ignition OFF.
- Review the results from the BCM-B self-test.
- Is DTC B1272:15 present?
Yes
GO to Y2.
No
GO to Y3.
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Y2 CHECK THE BCM-B REVERSING LAMP OUTPUT CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: BCM-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.
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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 Multifunction Electronic Modules Multifunction Electronic Modules or Computers and Control Systems as necessary.
No
For vehicles with an automatic transmission, REFER to Automatic Transaxle/Transmission - 6R80 Testing and Inspection to diagnose a Transmission Range (TR) input concern.
For vehicles with a manual transmission, GO to Y4.
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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 Service and Repair. TEST the system for normal operation.
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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.
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Y6 CHECK FOR CORRECT BCM-B OPERATION
- Disconnect all the BCM-B connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the BCM-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. REFER to Multifunction Electronic Modules Body Control Module B (BCM-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.
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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. REFER to Electronic Engine Controls 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.
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