Pinpoint Test K: One or More Stoplamps Are Inoperative
Stoplamps
Pinpoint Tests
Pinpoint Test K: One Or More Stoplamps Are Inoperative
Refer to Wiring Diagram Set 90, Turn Signal/Stop/Hazard Lamps for schematic and connector information. Diagrams By Number
Normal Operation - Fusion
When the brake pedal is applied, the stoplamp switch routes voltage to the Smart Junction Box (SJB). The voltage is then routed out of the SJB to the high mounted stoplamp through circuit CLS17 (YE/GY). When the SJB detects the brake pedal applied, the SJB provides voltage to the LH and RH rear stoplamps through circuit CLS18 (GY/BN) and circuit CLS19 (VT/OG). Ground for the rear stoplamps is provided through circuit GD171 (BK/GY).
Milan, MKZ
When the SJB detects the brake pedal applied, voltage is routed to the stoplamps through circuit CLS17 (YE/GY). Ground for the stoplamps is provided through circuit GD171 (BK/GY).
B2048-B2051:
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Bulb holder
- High mounted stoplamp
- Rear lamp assembly
- SJB
PINPOINT TEST K: ONE OR MORE STOPLAMPS ARE 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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K1 DETERMINE THE INOPERATIVE STOPLAMP
- Ignition OFF.
- Apply the brake pedal.
- Verify which stoplamp is inoperative.
- Is the high mounted stoplamp inoperative?
Yes
GO to K2.
No
GO to K5.
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K2 CHECK CIRCUIT CLS17 (YE/GY) FOR VOLTAGE
- Disconnect: High Mounted Stoplamp C475 (Parcel Shelf) or C4111 (Spoiler).
- While applying the brake pedal, measure the voltage between the high mounted stoplamp C475-1 (parcel shelf) or C4111-1 (spoiler), circuit CLS17 (YE/GY), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to K3.
No
For Fusion, GO to K4.
For Milan or MKZ, REPAIR the circuit CLS17 (YE/GY) for an open. TEST the system for normal operation.
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K3 CHECK CIRCUIT GD171 (BK/GY) FOR AN OPEN (HIGH MOUNTED STOPLAMP)
- Disconnect: Negative Battery Cable.
- Measure the resistance between the high mounted stoplamp C475-2 (parcel shelf) or C4111-3 (spoiler), circuit GD171 (BK/GY), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new high mounted stoplamp. REFER to High Mounted Stoplamp Service and Repair. TEST the system for normal operation.
No
REPAIR the circuit. TEST the system for normal operation.
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K4 CHECK CIRCUIT CLS17 (YE/GY) FOR AN OPEN (HIGH MOUNTED STOPLAMP)
- Disconnect: SJB C2280e.
- Measure the resistance between the high mounted stoplamp C475-1 (parcel shelf) or C4111-1 (spoiler), circuit CLS17 (YE/GY), harness side and the SJB C2280e-26, circuit CLS17 (YE/GY), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to K8.
No
REPAIR the circuit. TEST the system for normal operation.
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K5 CHECK FOR VOLTAGE TO THE INOPERATIVE REAR STOPLAMP
- Disconnect: Inoperative Rear Lamp.
- While applying the brake pedal, measure the voltage between the inoperative rear lamp, harness side and ground as follows:
- Is the voltage greater than 10 volts?
Yes
GO to K6.
No
For Milan or MKZ, REPAIR circuit CLS17 (YE/GY) for an open. TEST the system for normal operation.
For Fusion, GO to K7.
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K6 CHECK CIRCUIT GD171 (BK/GY) FOR AN OPEN (REAR STOPLAMP)
- Disconnect: Negative Battery Cable.
- Measure the resistance between the inoperative rear lamp, harness side and ground as follows:
- Is the resistance less than 5 ohms?
Yes
For Milan or MKZ, INSTALL a new rear lamp assembly. REFER to Rear Lamp Assembly Service and Repair. TEST the system for normal operation.
For Fusion, INSTALL a new bulb holder. CLEAR the DTCs. REPEAT the self-test.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
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K7 CHECK THE REAR STOPLAMP VOLTAGE SUPPLY CIRCUIT FOR AN OPEN AND A SHORT TO GROUND
- Disconnect: SJB C2280e.
- Measure the resistance between the inoperative rear lamp, harness side and the SJB, harness side; and between the inoperative rear lamp, harness side and ground as follows:
- Is the resistance less than 5 ohms between the rear lamp and the SJB, and greater than 10,000 ohms between the rear lamp and ground?
Yes
GO to K8.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
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K8 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. CLEAR the DTCs. REPEAT the self-test.
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