Pinpoint Test Z: The Trailer Stop/Turn Lamp Is Inoperative
Trailer Lamps
Pinpoint Tests
Pinpoint Test Z: The Trailer Stop/Turn Lamp Is Inoperative
Refer to Wiring Diagram Set 11, Fuse and Relay Information for schematic and connector information. Diagrams By Number
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 24 (15A) supplies voltage to the LH trailer tow stop/turn relay and BJB fuse 46 (15A) supplies voltage to the RH trailer tow stop/turn relay.
The trailer tow LH stop/turn relay coil receives voltage when the vehicle LH rear stoplamp is illuminated. When the trailer tow LH stop/turn relay is energized, voltage is routed to the trailer tow connector.
The trailer tow RH stop/turn relay coil receives voltage when the vehicle RH rear stoplamp is illuminated. When the trailer tow RH stop/turn relay is energized, voltage is routed to the trailer tow connector.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Trailer tow stop/turn relay
- BJB
- Trailer
PINPOINT TEST Z: THE TRAILER STOP/TURN LAMP IS INOPERATIVE
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
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Z1 CHECK FOR VOLTAGE TO THE TRAILER TOW CONNECTOR
- Ignition OFF.
- For the LH trailer stop/turn lamp, while applying the brake pedal, measure the voltage between the trailer tow C439-2, circuit CAT06 (YE), harness side and ground.
- For the RH trailer stop/turn lamp, while applying the brake pedal, measure the voltage between the trailer tow C439-1, circuit CAT09 (GN), harness 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
VERIFY the BJB fuse 24 (15A) (LH stop/turn relay) or fuse 46 (15A) (RH stop/turn relay) is OK. If OK, GO to Z2. If not OK, REFER to Wiring Diagrams to identify the possible causes of the circuit short. Diagrams By Number
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Z2 CHECK THE TRAILER TOW STOP/TURN RELAY
- Disconnect: Suspect Trailer Tow Stop/Turn Relay.
- Substitute a known good relay.
- For the LH trailer stop/turn lamp, while applying the brake pedal, measure the voltage between the trailer tow C439-2, circuit CAT06 (YE), harness side and ground.
- For the RH trailer stop/turn lamp, while applying the brake pedal, measure the voltage between the trailer tow C439-1, 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 stop/turn relay. TEST the system for normal operation.
No
REMOVE the known good relay. GO to Z3.
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Z3 CHECK FOR VOLTAGE TO THE STOP/TURN LAMP RELAY COIL
- 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; or between the trailer tow RH stop/turn relay pin 2, circuit CLS19 (VT/OG), BJB face side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to Z4.
No
REPAIR circuit CLS18 (GY/BN) (LH stop/turn) or circuit CLS19 (VT/OG) (RH stop/turn) for an open. TEST the system for normal operation.
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Z4 CHECK THE BJB
- Measure the voltage between the trailer tow LH stop/turn relay pin 3, BJB face side and ground; or between the trailer tow RH stop/turn relay pin 5, BJB face side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to Z5.
No
INSTALL a new BJB. TEST the system for normal operation.
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Z5 CHECK FOR VOLTAGE TO THE STOP/TURN LAMP RELAY USING THE RELAY GROUND PIN
- Measure the voltage between the trailer tow LH stop/turn relay pin 3, BJB face side and the trailer tow LH stop/turn relay pin 2, circuit GD120 (BK/GN), BJB face side.
- Measure the voltage between the trailer tow RH stop/turn relay pin 5, BJB face side and the trailer tow RH stop/turn relay pin 1, circuit GD120 (BK/GN), BJB face side.
- Is the voltage greater than 10 volts?
Yes
REPAIR circuit CAT06 (YE) (LH trailer stop/turn) or circuit CAT09 (GN) (RH trailer stop/turn) for an open. TEST the system for normal operation.
No
REPAIR circuit GD120 (BK/GN) for an open. TEST the system for normal operation.
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