Pinpoint Test J: One Or More Stoplamps Are Inoperative
Stoplamps
Pinpoint Tests
Pinpoint Test J: 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
When the brake pedal is applied, the stoplamp switch routes voltage to the Body Control Module (BCM), indicating the brake pedal is applied.
The BCM provides voltage to all the stoplamps (on independent circuits) when it detects the brake pedal is applied.
The LH stoplamps share the fused power source with the LH front turn lamp and the LH exterior mirror turn lamp.
The RH stoplamps share the fused power source with the RH front turn lamp and the RH exterior mirror turn lamp.
The high mounted stoplamp shares the fused power source with the reversing lamps.
The rear stoplamps share a common ground circuit.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Bulb socket
- High mounted stoplamp
- BCM
PINPOINT TEST J: 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: Make sure the bulb is good before continuing diagnostics.
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J1 DETERMINE THE INOPERATIVE STOPLAMP
- Ignition OFF.
- Apply the brake pedal and observe the stoplamps.
- Are all the stoplamps inoperative?
Yes
GO to Pinpoint Test I. Pinpoint Test I: All The Stoplamps Are Inoperative
No
For the high mounted stoplamp, GO to J2. If an individual rear stoplamp is inoperative, GO to J7. If both LH and RH rear stoplamps are inoperative, REPAIR circuit GD117 (BK) for an open. TEST the system for normal operation.
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J2 CHECK FOR VOLTAGE TO THE HIGH MOUNTED STOPLAMP
- Disconnect: High Mounted Stoplamp C904.
- While applying the brake pedal, measure the voltage between the high mounted stoplamp C904-3, circuit CLS52 (BN), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to J3.
No
VERIFY the BCM fuse 15 (15A) is OK. If OK, GO to J4. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. If no DTCs are present, TEST the system for normal operation. If DTC U1000:00 is present, CLEAR the DTCs and REPEAT the self-test (required to enable the stoplamp output driver if DTC U1000:00 is present). TEST the system for normal operation. If DTC U3000:49 is present, INSTALL a new BCM. REFER to Multifunction Electronic Modules Service and Repair. TEST the system for normal operation. Diagrams By Number
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J3 CHECK THE HIGH MOUNTED STOPLAMP GROUND CIRCUIT FOR AN OPEN
- While applying the brake pedal, measure the voltage between the high mounted stoplamp C904-3, circuit CLS52 (BN), harness side and the high mounted stoplamp C904-1, circuit GD139 (BK/YE), harness side.
- Is the voltage greater than 10 volts?
Yes
INSTALL a new high mounted stoplamp. TEST the system for normal operation.
No
REPAIR circuit GD139 (BK/YE) for an open. TEST the system for normal operation.
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J4 CARRY OUT THE BCM ON-DEMAND SELF-TEST AND RECHECK FOR VOLTAGE TO THE HIGH MOUNTED STOPLAMP
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: BCM Self-Test.
- Clear the DTCs and repeat the BCM on-demand self-test.
- While applying the brake pedal, measure the voltage between the high mounted stoplamp C904-3, circuit CLS52 (BN), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
INSTALL a new high mounted stoplamp. TEST the system for normal operation.
No
GO to J5.
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J5 CHECK THE HIGH MOUNTED STOPLAMP OUTPUT CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: BCM C2280D.
- Measure the resistance between the high mounted stoplamp C904-3, circuit CLS52 (BN), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to J6.
No
REPAIR circuit CLS52 (BN) for a short to ground. After the repair: If no DTCs are present, TEST the system for normal operation. If DTC U1000:00 is present, CLEAR the DTCs and REPEAT the self-test (required to enable the stoplamp output driver if DTC U1000:00 is present). TEST the system for normal operation. If DTC U3000:49 is present, INSTALL a new BCM. REFER to Multifunction Electronic Modules Service and Repair. TEST the system for normal operation.
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J6 CHECK THE HIGH MOUNTED STOPLAMP OUTPUT CIRCUIT FOR AN OPEN
- Measure the resistance between the high mounted stoplamp C904-3, circuit CLS52 (BN), harness side and the BCM C2280D-14, circuit CLS52 (BN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to J12.
No
REPAIR circuit CLS52 (BN) for an open. TEST the system for normal operation.
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J7 CHECK FOR VOLTAGE TO THE REAR STOPLAMP
- Disconnect: Inoperative Rear Lamp.
- While applying the brake pedal, measure the voltage between the inoperative lamp, harness side and ground as follows:
- Is the voltage greater than 10 volts?
Yes
GO to J8.
No
VERIFY the BCM fuse 14 (15A) (LH stoplamps) or fuse 13 (15A) (RH stoplamps) is OK. If OK, GO to J9. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Diagrams By Number
If no DTCs are present, TEST the system for normal operation. If DTC U1000:00 is present, CLEAR the DTCs and REPEAT the self-test (required to enable the stoplamp output driver if DTC U1000:00 is present). TEST the system for normal operation. If DTC U3000:49 is present, INSTALL a new BCM. REFER to Multifunction Electronic Modules Service and Repair. TEST the system for normal operation.
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J8 CHECK THE REAR STOPLAMP GROUND CIRCUIT FOR AN OPEN
- While applying the brake pedal, measure the voltage between the inoperative lamp, harness side and ground as follows:
- Is the voltage greater than 10 volts?
Yes
INSTALL a new bulb socket. TEST the system for normal operation.
No
REPAIR circuit GD176 (BK/WH) for an open. TEST the system for normal operation.
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J9 CARRY OUT THE BCM ON-DEMAND SELF-TEST AND RECHECK FOR VOLTAGE TO THE REAR STOPLAMP
NOTE: If both lamps are inoperative on the same side, disconnect one lamp at a time when carrying out this test.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: BCM Self-Test.
- Clear the DTCs and repeat the BCM on-demand self-test.
- While applying the brake pedal, measure the voltage between the inoperative lamp, harness side and ground as follows:
- Is the voltage greater than 10 volts?
Yes
INSTALL a new bulb socket. TEST the system for normal operation.
No
GO to J10.
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J10 CHECK THE REAR STOPLAMP VOLTAGE SUPPLY CIRCUIT FOR A SHORT TO GROUND
NOTE: It is important to disconnect the corresponding trailer tow stop/turn relay for correct test results.
- Ignition OFF.
- Disconnect: BCM C2280D.
- Disconnect: Corresponding Trailer Tow Stop/Turn Relay.
- Measure the resistance between the BCM C2280D-12 (LH stoplamps), circuit CLS18 (GY/BN), harness side and ground; or between the BCM C2280D-15 (RH stoplamps), circuit CLS19 (VT/OG), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to J11.
No
REPAIR circuit CLS18 (GY/BN) (LH stoplamps) or circuit CLS19 (VT/OG) (RH stoplamps) for a short to ground. After the repair: If no DTCs are present, TEST the system for normal operation. If DTC U1000:00 is present, CLEAR the DTCs and REPEAT the self-test (required to enable the stoplamp output driver if DTC U1000:00 is present). TEST the system for normal operation. If DTC U3000:49 is present, INSTALL a new BCM. REFER to Multifunction Electronic Modules Service and Repair. TEST the system for normal operation.
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J11 CHECK THE REAR STOPLAMP VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
- Measure the resistance between the inoperative rear lamp, harness side and the BCM, harness side as follows:
- Is the resistance less than 5 ohms?
Yes
GO to J12.
No
REPAIR circuit CLS18 (GY/BN) (LH stoplamps) or circuit CLS19 (VT/OG) (RH stoplamps) for an open. TEST the system for normal operation.
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J12 CHECK FOR CORRECT BCM OPERATION
- Disconnect all the BCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the BCM 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 BCM. REFER to Multifunction Electronic Modules 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.
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