Pinpoint Test T: The Trailer Lamps Are Inoperative - Trailer Stop/Turn Lamp
Trailer Lamps
Pinpoint Tests
Pinpoint Test T: The Trailer Lamps Are Inoperative - Trailer Stop/Turn Lamp
Refer to Wiring Diagram Set 95, Trailer/Camper Adapter for schematic and connector information. Diagrams By Number
Refer to Wiring Diagram Set 11, Fuse and Relay Information for schematic and connector information. Diagrams By Number
Normal Operation
The trailer tow LH stop/turn relay coil receives voltage through circuit CLS18 (GY/BN) when the vehicle LH rear stoplamp is illuminated. When the trailer tow LH stop/turn relay is energized, the voltage is routed to the trailer tow connector through circuit CAT06 (YE).
The trailer tow RH stop/turn relay coil receives voltage through circuit CLS19 (VT/OG) when the vehicle RH rear stoplamp is illuminated. When the trailer tow RH stop/turn relay is energized, the voltage is routed to the trailer tow connector through circuit CAT09 (GN).
The Battery Junction Box (BJB) fuse 48 (20A) supplies voltage to the switch side of both trailer tow stop/turn relays through circuit SBB48 (VT/RD). The trailer tow stop/turn relay coils are grounded through circuit GD123 (BK/GY).
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Trailer tow stop/turn relay
- Trailer tow connector
- Trailer
PINPOINT TEST T: THE TRAILER LAMPS ARE INOPERATIVE - TRAILER STOP/TURN LAMP
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
NOTE: Before beginning diagnostics, visually inspect the trailer tow connector for signs of corrosion or damage. Repair or install a new trailer tow connector as required.
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T1 DETERMINE IF BOTH TRAILER STOP/TURN LAMPS ARE INOPERATIVE
- Apply the brake pedal while observing the trailer lamps.
- Are both trailer stop/turn lamps inoperative?
Yes
VERIFY the BJB fuse 48 (20A) is OK. If OK, REPAIR circuit SBB48 (VT/RD) for an open. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short.
No
For an inoperative LH trailer lamp, GO to T2.
For an inoperative RH trailer lamp, GO to T8.
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T2 CHECK FOR VOLTAGE TO THE TRAILER TOW CONNECTOR (LH TURN)
- For vehicles equipped with a class I trailer tow package, while applying the brake pedal, measure the voltage between the trailer tow C4098-2, circuit CAT06 (YE), harness side and ground.
- For vehicles equipped with a class II trailer tow package, while applying the brake pedal, measure the voltage between the trailer tow connector LH stop/turn lamp voltage supply pin, circuit CAT06 (YE), component side and ground.
- Is the voltage greater than 10 volts?
Yes
The vehicle is operating correctly. SEND the trailer to an authorized camper/trailer repair facility.
No
For vehicles equipped with a class I trailer tow package, GO to T4.
For vehicles equipped with a class II trailer tow package, GO to T3.
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T3 CHECK FOR VOLTAGE TO THE TRAILER TOW CONNECTOR (7-PIN) (LH TURN)
- Disconnect: Trailer Tow C4099.
- While applying the brake pedal, measure the voltage between the trailer tow C4099-1, circuit CAT06 (YE), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
INSTALL a new trailer tow connector. TEST the system for normal operation.
No
GO to T4.
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T4 CHECK THE LH TRAILER TOW TURN RELAY
- Disconnect: LH Trailer Tow Stop/Turn Relay.
- Substitute a known good relay.
- For vehicles equipped with a class I trailer tow package, while applying the brake pedal, measure the voltage between the trailer tow C4098-2, circuit CAT06 (YE), harness side and ground.
- For vehicles equipped with a class II trailer tow package, while applying the brake pedal, measure the voltage between the trailer tow C4099-1, circuit CAT06 (YE), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
REMOVE the known good relay. INSTALL a new LH trailer tow stop/turn relay. TEST the system for normal operation.
No
REMOVE the known good relay. GO to T5.
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T5 CHECK THE STOPLAMP INPUT CIRCUIT TO THE LH TRAILER TOW STOP/TURN RELAY FOR AN OPEN
- While applying the brake pedal, measure the voltage between the trailer tow LH stop/turn relay pin 1, circuit CLS18 (GY/BN), BJB face side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to T6.
No
REPAIR circuit CLS18 (GY/BN) for an open. TEST the system for normal operation.
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T6 CHECK THE VOLTAGE SUPPLY CIRCUIT TO THE LH TRAILER TOW STOP/TURN RELAY FOR AN OPEN
- Measure the voltage between the trailer tow LH stop/turn relay pin 3, circuit SBB48 (VT/RD), BJB face side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to T7.
No
REPAIR circuit SBB48 (VT/RD) for an open. TEST the system for normal operation.
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T7 CHECK THE VOLTAGE SUPPLY CIRCUIT TO THE LH TRAILER TOW STOP/TURN RELAY USING THE RELAY GROUND CIRCUIT PIN
- Measure the voltage between the trailer tow LH stop/turn relay pin 3, circuit SBB48 (VT/RD), BJB face side and the trailer tow LH stop/turn relay pin 2, circuit GD123 (BK/GY), BJB face side.
- Is the voltage greater than 10 volts?
Yes
REPAIR circuit CAT06 (YE) for an open. TEST the system for normal operation.
No
REPAIR circuit GD123 (BK/GY) for an open. TEST the system for normal operation.
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T8 CHECK FOR VOLTAGE TO THE TRAILER TOW CONNECTOR (RH TURN)
- For vehicles equipped with a class I trailer tow package, while applying the brake pedal, measure the voltage between the trailer tow C4098-1, circuit CAT09 (GN), harness side and ground.
- For vehicles equipped with a class II trailer tow package, while applying the brake pedal, measure the voltage between the trailer tow connector RH stop/turn lamp voltage supply pin, circuit CAT09 (GN), component side and ground.
- Is the voltage greater than 10 volts?
Yes
The vehicle is operating correctly. SEND the trailer to an authorized camper/trailer repair facility.
No
For vehicles equipped with a class I trailer tow package, GO to T10.
For vehicles equipped with a class II trailer tow package, GO to T9.
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T9 CHECK FOR VOLTAGE TO THE TRAILER TOW CONNECTOR (7-PIN) (RH TURN)
- Disconnect: Trailer Tow C4099.
- While applying the brake pedal, measure the voltage between the trailer tow C4099-4, circuit CAT09 (GN), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
INSTALL a new trailer tow connector. TEST the system for normal operation.
No
GO to T10.
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T10 CHECK THE RH TRAILER TOW TURN RELAY
- Disconnect: RH Trailer Tow Stop/Turn Relay.
- Substitute a known good relay.
- For vehicles equipped with a class I trailer tow package, while applying the brake pedal, measure the voltage between the trailer tow C4098-1, circuit CAT09 (GN), harness side and ground.
- For vehicles equipped with a class II trailer tow package, while applying the brake pedal, measure the voltage between the trailer tow C4099-4, circuit CAT09 (GN), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
REMOVE the known good relay. INSTALL a new RH trailer tow stop/turn relay. TEST the system for normal operation.
No
REMOVE the known good relay. GO to T11.
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T11 CHECK THE STOPLAMP INPUT CIRCUIT TO THE RH TRAILER TOW STOP/TURN RELAY FOR AN OPEN
- While applying the brake pedal, measure the voltage between the trailer tow RH stop/turn relay pin 1, circuit CLS19 (VT/OG), BJB face side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to T12.
No
REPAIR circuit CLS19 (VT/OG) for an open. TEST the system for normal operation.
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T12 CHECK THE VOLTAGE SUPPLY CIRCUIT TO THE RH TRAILER TOW STOP/TURN RELAY FOR AN OPEN
- Measure the voltage between the trailer tow RH stop/turn relay pin 3, circuit SBB48 (VT/RD), BJB face side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to T13.
No
REPAIR circuit SBB48 (VT/RD) for an open. TEST the system for normal operation.
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T13 CHECK THE VOLTAGE SUPPLY CIRCUIT TO THE RH TRAILER TOW STOP/TURN RELAY USING THE RELAY GROUND CIRCUIT PIN
- Measure the voltage between the trailer tow RH stop/turn relay pin 3, circuit SBB48 (VT/RD), BJB face side and the trailer tow RH stop/turn relay pin 2, circuit GD123 (BK/GY), BJB face side.
- Is the voltage greater than 10 volts?
Yes
REPAIR circuit CAT09 (GN) for an open. TEST the system for normal operation.
No
REPAIR circuit GD123 (BK/GY) for an open. TEST the system for normal operation.
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