Pinpoint Test Z: The Individual Trailer Lamp Is Inoperative - Trailer Stop/Turn Lamp
Trailer Lamps
Pinpoint Tests
Pinpoint Test Z: The Individual Trailer Lamp Is 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 34 (25A) supplies voltage to both trailer tow stop/turn relays. The trailer tow stop/turn relay coils are grounded through circuit GD122 (BK).
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Trailer tow connector
- BJB
- Trailer tow stop/turn relay
- Trailer
PINPOINT TEST Z: THE INDIVIDUAL TRAILER LAMP IS INOPERATIVE - TRAILER STOP/TURN LAMP
NOTICE: It is important to install relays in their correct position in the Battery Junction Box (BJB). Installing a relay incorrectly can cause wiring shorts or damage to modules. While carrying out diagnostics on BJB relays, have only one BJB relay removed at a time. Failure to follow these instructions can result in damage to the vehicle circuitry or to controlling modules.
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 mounted on the bumper for signs of corrosion or damage. Repair or install a new trailer tow connector as required.
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Z1 CHECK FOR VOLTAGE THROUGH 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 connector LH stop/turn lamp voltage supply pins, circuit CAT06 (YE), component side and ground.
- For the RH trailer stop/turn lamp, while applying the brake pedal, measure the voltage between the trailer tow connector RH stop/turn lamp voltage supply pins, 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
GO to Z2.
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Z2 CHECK FOR VOLTAGE TO THE TRAILER TOW CONNECTOR (VEHICLE HARNESS)
- Disconnect: Trailer Tow C4099.
- For the LH trailer stop/turn lamp, while applying the brake pedal, measure the voltage between the trailer tow C4099-1, 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 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 Z3.
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Z3 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 C4099-1, 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 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 stop/turn relay. TEST the system for normal operation.
No
REMOVE the known good relay. GO to Z4.
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Z4 CHECK THE TRAILER TOW STOP/TURN RELAY INPUT CIRCUIT FOR VOLTAGE
- 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 1, circuit CLS19 (VT/OG), BJB face side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to Z5.
No
REPAIR the circuit in question. TEST the system for normal operation.
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Z5 CHECK THE TRAILER TOW STOP/TURN RELAY BJB VOLTAGE SUPPLY
- 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 3, BJB face side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to Z6.
No
VERIFY the BJB fuse 34 (25A) is OK. If OK, INSTALL a new BJB. TEST the system for normal operation.
If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short.
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Z6 CHECK FOR VOLTAGE TO CHECK THE TRAILER TOW STOP/TURN RELAY USING THE GROUND CIRCUIT
- For the LH trailer turn lamp, 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 GD122 (BK), BJB face side.
- Measure the voltage between the trailer tow RH stop/turn relay pin 3, BJB face side and the trailer tow RH stop/turn relay pin 2, circuit GD122 (BK), BJB face side.
- Is the voltage greater than 10 volts?
Yes
REPAIR circuit GD122 (BK) for an open. TEST the system for normal operation.
No
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.
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