Pinpoint Test Q: One or More Parking, Rear or License Plate Lamps Is Inoperative
Parking, Rear and License Plate Lamps
Pinpoint Tests
Pinpoint Test Q: One Or More Parking, Rear or License Plate Lamps Is Inoperative
Refer to Wiring Diagram Set 92, Parking, Rear and License Lamps for schematic and connector information. Diagrams By Number
Normal Operation
Voltage is supplied to the Smart Junction Box (SJB) from the Battery Junction Box (BJB) fuse 23 (60A) through circuit SBB23 (WH/RD).
When the headlamp switch is placed in the PARKING LAMPS ON position, the SJB provides a ground for the parking lamp relay coil (internal to the SJB). When the parking lamp relay is energized, voltage is sent through circuit CBP08 (GY/YE) to the rear and front parking lamps. Ground is provided to the rear parking and license plate lamps through circuit GD171 (BK/GY). Ground is provided to the front parking and side marker lamps through circuits GD121 (BK/YE) and GD123 (BK/GY).
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Bulb holder
- Rear lamp assembly
- SJB
PINPOINT TEST Q: ONE OR MORE PARKING, REAR OR LICENSE PLATE LAMPS IS INOPERATIVE
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
NOTE: Failure to disconnect the battery when instructed will result in false resistance readings. Refer to Battery.
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Q1 CHECK THE STOPLAMPS AND TURN LAMPS
- Ignition ON.
- Operate the turn signals and apply the brake pedal while observing the exterior lamps.
- Do the stoplamps and turn lamps operate correctly?
Yes
GO to Q2.
No
REFER to Stoplamps Testing and Inspection or Turn Signal and Hazard Lamps Testing and Inspection.
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Q2 DETERMINE IF ALL THE PARKING LAMPS ARE INOPERATIVE
- Ignition OFF.
- Place the headlamp switch in the PARKING LAMPS ON position.
- Are all the parking lamps inoperative?
Yes
PLACE the headlamp switch in the OFF position. VERIFY the SJB fuse 4 (15A) is OK. If OK, GO to Q7. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short.
No
If all front parking lamps are inoperative, GO to Q3.
If all rear parking and license plate lamps are inoperative, GO to Q4.
If an individual parking or license plate lamp is inoperative, GO to Q5.
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Q3 CHECK CIRCUIT CBP08 (GY/YE) FOR AN OPEN (FRONT LAMPS)
- Place the headlamp switch in the OFF position.
- Disconnect: SJB C2280a.
- Connect a fused jumper wire between the SJB C2280a-4, circuit SBB19 (RD/BU), harness side and the SJB C2280a-31, circuit CBP08 (GY/YE), harness side
- Do the front parking lamps illuminate?
Yes
REMOVE the jumper wire. GO to Q7.
No
REPAIR the circuit. TEST the system for normal operation.
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Q4 CHECK CIRCUIT CBP08 (GY/YE) FOR AN OPEN (REAR LAMPS)
- Place the headlamp switch in the OFF position.
- Disconnect: SJB C2280e.
- Connect a fused jumper wire between the positive battery terminal and the SJB C2280e-30, circuit CBP08 (GY/YE), harness side
- Do the rear parking lamps illuminate?
Yes
REMOVE the jumper wire. GO to Q7.
No
REPAIR the circuit. TEST the system for normal operation.
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Q5 CHECK CIRCUIT CBP08 (GY/YE) FOR AN OPEN
- Disconnect: Inoperative Parking Lamp.
- Place the headlamp switch in the PARKING LAMPS ON position.
- Measure the voltage between the inoperative lamp, harness side and ground as follows:
- Is the voltage greater than 10 volts?
Yes
GO to Q6.
No
REPAIR the circuit. TEST the system for normal operation.
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Q6 CHECK THE PARKING LAMP GROUND CIRCUIT FOR AN OPEN
- Place the headlamp switch in the OFF position.
- Disconnect: Negative Battery Cable.
- Measure the resistance between the inoperative lamp, harness side and ground as follows:
- Is the resistance less than 5 ohms?
Yes
For Milan or MKZ rear lamp, INSTALL a new rear lamp assembly. REFER to Rear Lamp Assembly Service and Repair. TEST the system for normal operation.
For any other parking lamp, INSTALL a new bulb holder. TEST the system for normal operation.
No
REPAIR the ground circuit in question for an open. TEST the system for normal operation.
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Q7 CHECK FOR CORRECT SJB OPERATION
- Disconnect all the SJB connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SJB 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 SJB. REFER to Body Control Systems. 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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