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 (Fusion/Milan/MKZ, Fusion Hybrid, Milan Hybrid, MKZ Hybrid), Reversing Lamps for schematic and connector information. Diagrams By Number
Normal Operation
Voltage is supplied from the Battery Junction Box (BJB) fuse 47 (10A) to the coil and switched sides of the reversing lamps relay. When the reversing lamps relay is energized, voltage is routed to the reversing lamps.
Automatic Transaxle
The PCM (2.5L or 3.0L engines) or the Transmission Control Module (TCM) (3.5L engine) monitors the transaxle gear status. When the PCM detects the transaxle is in REVERSE (R), the PCM or TCM provides ground for the reversing lamps relay coil.
Manual Transaxle
The reversing lamp switch controls the coil ground side of the reversing lamps relay. When the transaxle is in REVERSE (R), the reversing lamp switch contacts close, completing the path to ground for the reversing lamps relay coil.
- DTC P1910 (Reverse Lamp Control Circuit/Open) - sets when the PCM detects no voltage on the reversing lamp relay coil ground control circuit (if the coil ground control circuit is short to ground).
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Reversing lamps relay
- Reversing lamp switch
- Auto-dimming interior mirror
- PCM
- TCM
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 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 Rear View Mirrors Interior Rear View Mirror. 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 Reversing Lamp Switch Service and Repair. 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 Testing and Inspection.
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 Automatic Transaxle/Transmission - Aisin AW21 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.
-------------------------------------------------
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 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. CLEAR any DTCs. REPEAT the self-test.
-------------------------------------------------