Pinpoint Test U: Both Reversing Lamps Are Inoperative
Reversing Lamps
Pinpoint Tests
Pinpoint Test U: Both Reversing Lamps Are Inoperative
Refer to Wiring Diagram Set 93, Reversing Lamps for schematic and connector information. Diagrams By Number
Normal Operation
Voltage is supplied from the Battery Junction Box (BJB) fuse 26 (15A) to the coil side of the reversing lamps relay. The reversing lamps relay switch side is supplied voltage by the BJB fuse 7 (10A). The reversing lamps relay coil ground is controlled by the PCM. When the transaxle is in REVERSE (R), the PCM completes the ground, energizing the reversing lamps relay. When the reversing lamps relay is energized, voltage is routed to the reversing lamps. The reversing lamps share a common ground with the stoplamps.
Automatic Transaxle
The PCM sets digital Transmission Range (TR) sensor related DTCs if any concerns exist with inputs from the TR sensor.
Manual Transaxle
The PCM sends a voltage signal to the reversing lamps switch. When the transaxle is in REVERSE (R), the voltage signal is routed back to the PCM through the signal return circuit.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Reversing lamps relay
- Reversing lamp switch (manual transaxle)
- PCM
PINPOINT TEST U: BOTH REVERSING LAMPS ARE INOPERATIVE
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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U1 CHECK THE REVERSING LAMPS RELAY
- Disconnect: Reversing Lamps Relay.
- Ignition ON.
- Substitute a known good relay and recheck the reversing lamps operation.
- Do the reversing lamps operate correctly?
Yes
REMOVE the known good relay. INSTALL a new reversing lamps relay. TEST the system for normal operation.
No
REMOVE the known good relay. GO to U2.
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U2 CHECK FOR VOLTAGE TO THE REVERSING LAMPS RELAY
- Ignition OFF.
- Measure the voltage between the reversing lamps relay pin 3, circuit SBB07 (WH/RD), BJB face side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to U3.
No
VERIFY the BJB fuse 7 (10A) is OK. If OK, REPAIR circuit SBB07 (WH/RD) for an open. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Diagrams By Number
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U3 BYPASS THE REVERSING LAMPS RELAY
- Connect a fused jumper wire between the reversing lamps relay pin 3, circuit SBB07 (WH/RD), BJB face side and the reversing lamps relay pin 5, circuit CLS10 (GN/BN), BJB face side.
- Do the reversing lamps illuminate?
Yes
REMOVE the jumper wire. GO to U4.
No
REMOVE the jumper wire. REPAIR circuit CLS10 (GN/BN) for an open. TEST the system for normal operation.
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U4 CHECK FOR VOLTAGE TO THE REVERSING LAMPS RELAY COIL
- Ignition ON.
- Measure the voltage between the reversing lamps relay pin 1, circuit CBB26 (BU/WH), BJB face side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to U5.
No
REPAIR circuit CBB26 (BU/WH) for an open. TEST the system for normal operation.
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U5 CHECK FOR VOLTAGE TO THE PCM
- Ignition OFF.
- Connect: Reversing Lamps Relay.
- Disconnect: PCM C175t.
- Ignition ON.
- Measure the voltage between the PCM C175t-34, circuit CLS28 (BU/WH), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
For vehicles with an automatic transaxle, GO to U6.
For vehicles with a manual transaxle, GO to U7.
No
REPAIR circuit CLS28 (BU/WH) for an open. TEST the system for normal operation.
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U6 CHECK THE DIGITAL TR SENSOR INPUT
- Ignition OFF.
- Connect: PCM C175t.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: PCM DataLogger.
- Monitor the PCM transmission gear status PID (TR) while placing the gear selector lever through all its positions.
- Does the PID agree with the gear selection?
Yes
GO to U10.
No
REFER to Automatic Transaxle/Transmission - 4F27E Testing and Inspection to continue diagnosis of the digital TR sensor.
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U7 CHECK THE REVERSING LAMP SWITCH INPUT
- Ignition OFF.
- Select REVERSE.
- Measure the resistance between the PCM C175t-17, circuit CET47 (BU), harness side and the PCM C175t-40, circuit RE242 (GN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to U10.
No
GO to U8.
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U8 BYPASS THE REVERSING LAMP SWITCH
- Disconnect: Reversing Lamp Switch C169.
- Connect a fused jumper wire between the reversing lamp switch C169-2, circuit CET47 (BU), harness side and the reversing lamp switch C169-1, circuit RE242 (GN), harness side.
- Measure the resistance between the PCM C175t-17, circuit CET47 (BU), harness side and the PCM C175t-40, circuit RE242 (GN), harness side.
- Is the resistance less than 5 ohms?
Yes
REMOVE the jumper wire. INSTALL a new reversing lamp switch. REFER to Reversing Lamp Switch Service and Repair. TEST the system for normal operation.
No
REMOVE the jumper wire. GO to U9.
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U9 CHECK THE REVERSING LAMP SWITCH INPUT CIRCUIT FOR AN OPEN
- Measure the resistance between the reversing lamp switch C169-2, circuit CET47 (BU), harness side and the PCM C175t-17, circuit CET47 (BU), harness side.
- Is the resistance less than 5 ohms?
Yes
REPAIR circuit RE242 (GN) for an open. TEST the system for normal operation.
No
REPAIR circuit CET47 (BU) for an open. TEST the system for normal operation.
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U10 CHECK FOR CORRECT PCM OPERATION
- Ignition OFF.
- 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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