Pinpoint Test Y: The Reversing Lamps Are On Continuously

WARNING: This page is about a different car, the 2010 Mercury Milan, 2010 Lincoln MKZ, and 2010 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.

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

Y1 CHECK THE REVERSING LAMPS RELAY
- Ignition OFF.
- Substitute a known good relay.
- Ignition ON.
- Do the reversing lamps continue to illuminate?
- Yes: REMOVE the known good relay. GO to Y2.
- No: REMOVE the known good relay. INSTALL a new reversing lamps relay. TEST the system for normal operation.
Y2 CHECK THE REVERSING LAMPS RELAY OUTPUT
- Ignition OFF.
- Disconnect: Reversing Lamps Relay.
- Ignition ON.
- Do the reversing lamps continue to illuminate?
- Yes: If equipped with an auto-dimming interior mirror, GO to Y3.
  If not equipped with an auto-dimming interior mirror, REPAIR circuit CLS10 (GN/BN) for a short to voltage. TEST the system for normal operation.
- No: For vehicles with a manual transaxle, GO to Y4.
  For vehicles with an automatic transaxle, GO to Y5.
Y3 ISOLATE THE SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: Auto-Dimming Interior Mirror C911, C9030 or C9039.
- Ignition ON.
- Do the reversing lamps continue to illuminate?
- Yes: REPAIR circuit CLS10 (GN/BN) for a short to voltage. TEST the system for normal operation.
  GO to Y4.
- No: INSTALL a new auto-dimming interior mirror. REFER to INSTALLATION . TEST the system for normal operation.
Y4 CHECK THE REVERSING LAMP SWITCH
- Ignition OFF.
- Connect: Reversing Lamps Relay.
- Disconnect: Reversing Lamp Switch C169.
- Ignition ON.
- Do the reversing lamps continue to illuminate?
- Yes: REPAIR circuit CLS28 (BU/WH) for a short to ground. TEST the system for normal operation.
- No: INSTALL a new reversing lamp switch. REFER to Removal and Installation . TEST the system for normal operation.
Y5 CHECK FOR PCM OR TCM TR SENSOR DTCs FROM THE SELF-TEST
- Review the DTCs from the PCM (2.5L or 3.0L engine) or the TCM (3.5L engine) Key ON Engine OFF (KOEO) self-test.
- Are any TR sensor DTCs present?
- Yes: REFER to AUTOMATIC TRANSAXLE/TRANSMISSION - AISIN AW21 , DIAGNOSIS AND TESTING or AUTOMATIC TRANSAXLE/TRANSMISSION - ELECTONICALLY CONTOLLED CONTINUOUSLY VARIABLE TRANSMISSION (ECVT) .
- No: GO to Y6.
Y6 CHECK THE REVERSING LAMPS RELAY CONTROL CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Connect: Reversing Lamps Relay.
- Disconnect: PCM C175t (2.5L or 3.0L Engine,).
- Disconnect: TCM C1533 (3.5L Engine).
- Ignition ON.
- Do the reversing lamps continue to illuminate?
- Yes: REPAIR circuit CLS28 (BU/WH) for a short to ground. TEST the system for normal operation.
- No: For vehicles with a 3.5L engine, GO to Y7.
  For all other vehicles, GO to Y8.
Y7 CHECK FOR CORRECT TCM OPERATION
- Disconnect the TCM connector.
- Check for:
  - corrosion
  - damaged pins
  - pushed-out pins
- Connect the TCM connector and make sure it seats correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
- Yes: INSTALL a new TCM. REFER to INSTALLATION . 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.
Y8 CHECK FOR CORRECT PCM OPERATION
- Disconnect the PCM connector.
- Check for:
  - corrosion
  - damaged pins
  - pushed-out pins
- Connect the PCM connector and make sure it seats correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
- Yes: INSTALL a new PCM. REFER to INSTALLATION , INSTALLATION , INSTALLATION or INSTALLATION . 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 any DTCs. REPEAT the self-test.