Pinpoint Test Z: The Individual Trailer Lamp Is Inoperative - Trailer Turn/Stoplamp
Trailer Lamps
Pinpoint Tests
Pinpoint Test Z: The Individual Trailer Lamp Is Inoperative - Trailer Turn/Stoplamp
Refer to Wiring Diagram Set 95, Trailer/Camper Adapter for schematic and connector information. Diagrams By Number
Normal Operation
The Battery Junction Box (BJB) fuse 45 (25A) supplies voltage to both trailer tow turn relays.
The trailer tow LH turn relay coil receives voltage when the vehicle's LH rear stoplamp is illuminated. When the trailer tow LH turn relay is energized, the voltage is routed to the trailer tow connector.
The trailer tow RH turn relay coil receives voltage when the vehicle's RH rear stoplamp is illuminated. When the trailer tow RH turn relay is energized, the voltage is routed to the trailer tow connector.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Trailer tow turn relay
- Trailer
PINPOINT TEST Z: THE INDIVIDUAL TRAILER LAMP IS INOPERATIVE - TRAILER TURN/STOPLAMP
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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Z1 VERIFY THE TRAILER LAMP OPERATION
- Ignition OFF.
- Determine if both trailer stop/turn lamps are inoperative.
- Are both trailer stop/turn lamps inoperative?
Yes
VERIFY the BJB fuse 45 (25A) is OK. If OK, REPAIR circuit SBB45 (GY/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. Diagrams By Number
No
For an inoperative LH trailer lamp, GO to Z2.
For an inoperative RH trailer lamp, GO to Z8.
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Z2 CHECK FOR VOLTAGE THROUGH THE TRAILER TOW CONNECTOR (LH TRAILER STOP/TURN LAMP)
- For the 4-pin connector, while applying the brake pedal, measure the voltage between the trailer tow C4098-2, circuit CAT06 (YE), harness side and ground.
- For the 7-pin connector, while applying the brake pedal, measure the voltage between the trailer tow connector pin 1, 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 the 4-pin connector, GO to Z4.
For the 7-pin connector, GO to Z3.
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Z3 CHECK FOR VOLTAGE TO THE TRAILER TOW CONNECTOR (LH STOP/TURN 7-PIN)
- 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 Z4.
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Z4 CHECK THE TRAILER TOW LH STOP/TURN RELAY
- Disconnect: Trailer Tow LH Stop/Turn Relay.
- Substitute a known good relay.
- For the 4-pin connector, while applying the brake pedal, measure the voltage between the trailer tow C4098-2, circuit CAT06 (YE), harness side and ground.
- For the 7-pin connector, 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 trailer tow turn relay. TEST the system for normal operation.
No
REMOVE the known good relay. GO to Z5.
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Z5 CHECK FOR VOLTAGE TO THE LH STOP/TURN LAMP RELAY COIL
- While applying the brake pedal, measure the voltage between the trailer tow LH turn relay pin 1, circuit CLS18 (GY/BN), BJB face side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to Z6.
No
REPAIR circuit CLS18 (GY/BN) for an open. TEST the system for normal operation.
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Z6 CHECK THE VOLTAGE SUPPLY CIRCUIT TO THE LH STOP/TURN LAMP RELAY
- Measure the voltage between the trailer tow LH turn relay pin 3, circuit SBB45 (GY/RD), BJB face side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to Z7.
No
REPAIR circuit SBB45 (GY/RD) for an open. TEST the system for normal operation.
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Z7 CHECK THE VOLTAGE SUPPLY CIRCUIT TO THE LH STOP/TURN LAMP RELAY USING THE RELAY GROUND PIN
- Measure the voltage between the trailer tow LH turn relay pin 3, circuit SBB45 (GY/RD), BJB face side and the trailer tow LH 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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Z8 CHECK FOR VOLTAGE THROUGH THE TRAILER TOW CONNECTOR (RH TRAILER STOP/TURN LAMP)
- For the 4-pin connector, while applying the brake pedal, measure the voltage between the trailer tow C4098-1, circuit CAT09 (GN), harness side and ground.
- For the 7-pin connector, while applying the brake pedal, measure the voltage between the trailer tow connector pin 4, 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 the 4-pin connector, GO to Z10.
For the 7-pin connector, GO to Z9.
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Z9 CHECK FOR VOLTAGE TO THE TRAILER TOW CONNECTOR (RH STOP/TURN 7-PIN)
- 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 Z10.
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Z10 CHECK THE TRAILER TOW RH STOP/TURN RELAY
- Disconnect: Trailer Tow RH Stop/Turn Relay.
- Substitute a known good relay.
- For the 4-pin connector, while applying the brake pedal, measure the voltage between the trailer tow C4098-1, circuit CAT09 (GN), harness side and ground.
- For the 7-pin connector, 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 trailer tow turn relay. TEST the system for normal operation.
No
REMOVE the known good relay. GO to Z11.
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Z11 CHECK FOR VOLTAGE TO THE RH STOP/TURN LAMP RELAY COIL
- While applying the brake pedal, measure the voltage between the trailer tow RH turn relay pin 1, circuit CLS19 (VT/OG), BJB face side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to Z12.
No
REPAIR circuit CLS19 (VT/OG) for an open. TEST the system for normal operation.
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Z12 CHECK THE VOLTAGE SUPPLY CIRCUIT TO THE RH STOP/TURN LAMP RELAY
- Measure the voltage between the trailer tow RH turn relay pin 3, circuit SBB45 (GY/RD), BJB face side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to Z13.
No
REPAIR circuit SBB45 (GY/RD) for an open. TEST the system for normal operation.
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Z13 CHECK THE VOLTAGE SUPPLY CIRCUIT TO THE RH STOP/TURN LAMP RELAY USING THE RELAY GROUND PIN
- Measure the voltage between the trailer tow RH turn relay pin 3, circuit SBB45 (GY/RD), BJB face side and the trailer tow RH 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 ground GD123 (BK/GY) for an open. TEST the system for normal operation.
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