Pinpoint Test U: The Trailer Parking Lamps Are Inoperative
Trailer Lamps
Pinpoint Tests
Pinpoint Test U: The Trailer Parking Lamps Are 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 trailer tow parking lamp relay coil receives voltage when the vehicle parking lamps are illuminated. The Battery Junction Box (BJB) fuse 57 (20A) supplies voltage to the trailer tow parking lamp relay switch side. When the trailer tow parking lamp 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 parking lamp relay
- Trailer tow connector
- Trailer
PINPOINT TEST U: THE TRAILER PARKING LAMPS ARE INOPERATIVE
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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U1 CHECK FOR VOLTAGE TO THE TRAILER TOW CONNECTOR
- Ignition OFF.
- Place the headlamp switch in the PARKING LAMPS ON position.
- For vehicles equipped with a class I trailer tow package, measure the voltage between the trailer tow C4098-3, circuit CAT17 (BN), harness side and ground.
- For vehicles equipped with a class II trailer tow package, measure the voltage between the trailer tow parking lamp voltage supply pin, circuit CAT17 (BN), 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
VERIFY the BJB fuse 57 (20A) is OK. If OK:
For vehicles equipped with a class I trailer tow package, GO to U3.
For vehicles equipped with a class II trailer tow package, GO to U2.
If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Diagrams By Number
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U2 CHECK FOR VOLTAGE TO THE TRAILER TOW CONNECTOR (7-PIN)
- Disconnect: Trailer Tow C4099.
- Measure the voltage between the trailer tow C4099-6, circuit CAT17 (BN), 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 U3.
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U3 CHECK THE TRAILER TOW PARKING LAMP RELAY
- Place the headlamp switch in the OFF position.
- Disconnect: Trailer Tow Parking Lamp Relay .
- Substitute a known good relay.
- Place the headlamp switch in the PARKING LAMPS ON position.
- For vehicles equipped with a class I trailer tow package, measure the voltage between the trailer tow C4098-3, circuit CAT17 (BN), harness side and ground.
- For vehicles equipped with a class II trailer tow package, measure the voltage between the trailer tow C4099-6, circuit CAT17 (BN), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
REMOVE the known good relay. INSTALL a new trailer tow parking lamp relay. TEST the system for normal operation.
No
REMOVE the known good relay. GO to U4.
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U4 CHECK THE PARKING LAMP INPUT CIRCUIT TO THE RH TRAILER TOW STOP/TURN RELAY FOR AN OPEN
- Measure the voltage between the trailer tow parking lamp relay pin 1, circuit CLS30 (VT/WH), BJB face side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to U5.
No
REPAIR circuit CLS30 (VT/WH) for an open. TEST the system for normal operation.
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U5 CHECK THE VOLTAGE SUPPLY CIRCUIT TO THE RH TRAILER TOW STOP/TURN RELAY FOR AN OPEN
- Measure the voltage between the trailer tow parking lamp relay pin 3, circuit SBB57 (RD), BJB face side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to U6.
No
REPAIR circuit SBB57 (RD) for an open. TEST the system for normal operation.
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U6 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 parking lamp relay pin 3, circuit SBB57 (RD), BJB face side and the trailer tow parking lamp relay pin 2, circuit GD123 (BK/GY), BJB face side.
- Is the voltage greater than 10 volts?
Yes
REPAIR circuit CAT17 (BN) 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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