Pinpoint Test I: The Stoplamps Are On Continuously
Stoplamps
Pinpoint Tests
Pinpoint Test I: The Stoplamps Are On Continuously
Refer to Wiring Diagram Set 90, Turn Signal/Stop/Hazard Lamps for schematic and connector information. Diagrams By Number
Refer to Wiring Diagram Set 140, Customer Access for schematic and connector information. Diagrams By Number
Normal Operation - Wagon
When the brake pedal is applied, the stoplamp switch routes voltage to the Smart Junction Box (SJB), the PCM, the high mounted stoplamp and the aftermarket trailer electric brake controller (if equipped). When the SJB detects the brake pedal is applied, the SJB provides voltage to the LH and RH rear stoplamps.
Cutaway and Stripped Chassis
When the brake pedal is applied, the stoplamp switch routes voltage to the SJB, the PCM and the body builder connector. When the SJB detects the brake pedal is applied, the SJB provides voltage to the LH and RH rear stoplamps through the body builder connector.
- DTC B1485 (Brake Pedal Input Short to Battery) - an on-demand DTC that sets when the SJB detects a short to voltage from the stoplamp switch input circuit.
- DTC B2045 (Left Rear Stop Lamp Circuit Open) - an on-demand DTC that sets when the SJB detects a short to voltage from the LH rear stop/turn lamp voltage supply circuit.
- DTC B2047 (Right Rear Stop Lamp Circuit Open) - an on-demand DTC that sets when the SJB detects a short to voltage from the RH rear stop/turn lamp voltage supply circuit.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Stoplamp switch
- Body builder equipment
- Trailer electric brake controller
- PCM
- SJB
PINPOINT TEST I: THE STOPLAMPS ARE ON CONTINUOUSLY
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I1 CHECK THE RECORDED DTCs FROM THE SJB SELF-TEST
- Ignition OFF.
- Check the recorded results from the SJB on-demand self-test.
- Is DTC B1485 present?
Yes
GO to I2.
No
For cutaway and stripped chassis vehicles, GO to I11.
For wagon, GO to I13.
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I2 CHECK THE VEHICLE FOR AN AFTERMARKET TRAILER ELECTRIC BRAKE CONTROLLER
- Check the vehicle for a customer installed aftermarket trailer electric brake controller.
- Is an aftermarket trailer electric brake controller present?
Yes
GO to I3.
No
For cutaway and stripped chassis vehicles, GO to I4.
For wagon, GO to I8.
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I3 CHECK THE TRAILER ELECTRIC BRAKE CONTROLLER FOR THE CAUSE OF THE CONCERN
- Disconnect: Trailer Electric Brake Controller C2142.
- Do the stoplamps continue to illuminate?
Yes
For cutaway and stripped chassis vehicles, GO to I4.
For wagon, GO to I8.
No
INSTALL a new trailer electric brake controller. TEST the system for normal operation.
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I4 CHECK THE STOPLAMP SWITCH (CUTAWAY AND STRIPPED CHASSIS VEHICLES)
- Disconnect: Stoplamp Switch C278.
- Do the stoplamps continue to illuminate?
Yes
GO to I5.
No
INSTALL a new stoplamp switch. REFER to Stoplamp Switch Service and Repair. TEST the system for normal operation.
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I5 ISOLATE THE PCM AS THE CAUSE OF THE CONCERN (CUTAWAY AND STRIPPED CHASSIS VEHICLES)
- Disconnect: PCM C175b (4.6L or 5.4L).
- Disconnect: PCM C1551b (6.8L).
- Disconnect: PCM C1381b (Diesel).
- Do the stoplamps continue to illuminate?
Yes
GO to I6.
No
GO to I14.
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I6 ISOLATE THE BODY BUILDER EQUIPMENT AS THE CAUSE OF THE CONCERN
- Disconnect: Body Builder C432.
- Do the LH and RH stoplamps continue to illuminate?
Yes
The vehicle is operating correctly. REFER to the body builder manual to continue diagnosis.
No
GO to I7.
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I7 CHECK THE STOPLAMP SWITCH OUTPUT CIRCUIT FOR A SHORT TO VOLTAGE (CUTAWAY OR STRIPPED CHASSIS)
- Disconnect: SJB C2280b.
- Measure the voltage between the SJB C2280b-40, circuit CCB08 (VT/WH), harness side and ground.
- Is any voltage present?
Yes
REPAIR circuit CCB08 (VT/WH) for a short to voltage. TEST the system for normal operation.
No
GO to I15.
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I8 CHECK THE STOPLAMP SWITCH (WAGON)
- Disconnect: Stoplamp Switch C278.
- Do the stoplamps continue to illuminate?
Yes
GO to I9.
No
INSTALL a new stoplamp switch. REFER to Stoplamp Switch Service and Repair. TEST the system for normal operation.
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I9 ISOLATE THE PCM AS THE CAUSE OF THE CONCERN (WAGON)
- Disconnect: PCM C175b (4.6L or 5.4L).
- Disconnect: PCM C1551b (6.8L).
- Disconnect: PCM C1381b (Diesel).
- Do the stoplamps continue to illuminate?
Yes
GO to I10.
No
GO to I14.
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I10 CHECK THE STOPLAMP SWITCH OUTPUT CIRCUIT FOR A SHORT TO VOLTAGE (WAGON)
- Disconnect: SJB C2280b.
- Does the high mounted stoplamp continue to illuminate?
Yes
REPAIR circuit CCB08 (VT/WH) for a short to voltage. TEST the system for normal operation.
No
GO to I15.
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I11 CHECK THE STOPLAMPS VOLTAGE SUPPLY CIRCUIT FOR A SHORT TO VOLTAGE (CUTAWAY OR STRIPPED CHASSIS)
- Disconnect: SJB C2280d.
- Do the stoplamps continue to illuminate?
Yes
GO to I12.
No
GO to I15.
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I12 ISOLATE THE STOPLAMPS VOLTAGE SUPPLY CIRCUIT FOR A SHORT TO VOLTAGE (CUTAWAY OR STRIPPED CHASSIS)
- Disconnect: Body Builder C432.
- Do the stoplamps continue to illuminate?
Yes
The vehicle is operating correctly. REFER to the body builder manual to continue diagnosis.
No
REPAIR circuit CLS18 (GY/BN) (LH stoplamp) or circuit CLS19 (VT/OG) (RH stoplamp) for a short to voltage. TEST the system for normal operation.
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I13 CHECK THE STOPLAMPS VOLTAGE SUPPLY CIRCUIT FOR A SHORT TO VOLTAGE (WAGON)
- Disconnect: SJB C2280d.
- Do the stoplamps continue to illuminate?
Yes
REPAIR circuit CLS18 (GY/BN) (LH stoplamp) or circuit CLS19 (VT/OG) (RH stoplamp) for a short to voltage. TEST the system for normal operation.
No
GO to I15.
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I14 CHECK FOR CORRECT PCM OPERATION
- Disconnect all the PCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the PCM 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 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. TEST the system for normal operation.
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I15 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 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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