Pinpoint Test J: The Stoplamps Are Inoperative
Stoplamps
Pinpoint Tests
Pinpoint Test J: The Stoplamps Are Inoperative
Refer to Wiring Diagram Set 90, Turn Signal/Stop/Hazard Lamps for schematic and connector information. Diagrams By Number
Normal Operation
For all vehicles, the stoplamp switch is supplied voltage through circuit SBP04 (GN/RD) from the Smart Junction Box (SJB). When the brake pedal is applied, the stoplamp switch routes voltage to the SJB through circuit CCB08 (VT/WH).
For the Milan and MKZ, the voltage is then routed to the stoplamps through circuit CLS17 (YE/GY).
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Stoplamp switch
- SJB
PINPOINT TEST J: THE 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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J1 CHECK CIRCUIT SBP04 (GN/RD) FOR VOLTAGE
- Ignition OFF.
- Disconnect: Stoplamp Switch C278.
- Measure the voltage between the stoplamp switch C278-1, circuit SBP04 (GN/RD), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to J3.
No
VERIFY the SJB fuse 21 (7.5A) is OK. If OK, GO to J2. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short.
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J2 CHECK CIRCUIT SBP04 (GN/RD) FOR AN OPEN
- Disconnect: SJB C2280a.
- Measure the resistance between the stoplamp switch C278-1, circuit SBP04 (GN/RD), harness side and the SJB C2280a-8, circuit SBP04 (GN/RD), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to J6.
No
REPAIR the circuit. TEST the system for normal operation.
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J3 CHECK THE STOPLAMP SWITCH
- Connect a fused jumper wire between the stoplamp switch C278-1, circuit SBP04 (GN/RD), harness side and the stoplamp switch C278-4, circuit CCB08 (VT/WH), harness side.
- Are the stoplamps illuminated?
Yes
REMOVE the jumper wire. INSTALL a new stoplamp switch. REFER to Stoplamp Switch Service and Repair. TEST the system for normal operation.
No
REMOVE the jumper wire. GO to J4.
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J4 CHECK CIRCUIT CCB08 (VT/WH) FOR AN OPEN
- Disconnect: SJB C2280a.
- Measure the resistance between the stoplamp switch C278-4, circuit CCB08 (VT/WH), harness side and the SJB C2280a-19, circuit CCB08 (VT/WH), harness side.
- Is the resistance less than 5 ohms?
Yes
For Fusion, GO to J6.
For Milan or MKZ, GO to J5.
No
REPAIR the circuit. TEST the system for normal operation.
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J5 CHECK CIRCUIT CLS17 (YE/GY) FOR AN OPEN
- Disconnect: SJB C2280e.
- Disconnect: High Mounted Stoplamp C475 (Parcel Shelf) or C4111 (Spoiler).
- 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 J6.
No
REPAIR the circuit. TEST the system for normal operation.
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J6 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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