Pinpoint Test AA: The Trailer Parking Lamps Are Inoperative
Trailer Lamps
Pinpoint Test AA: The Trailer Parking Lamps Are Inoperative
Refer to Wiring Diagrams Set 95, Trailer/Camper Adapter for schematic and connector information. Electrical Diagrams
Normal Operation
The trailer tow parking lamp relay coil receives voltage when the vehicle parking lamps are illuminated. The Smart Junction Box (SJB) fuse 38 (20A) supplies voltage to the trailer tow parking lamp relay switch side. When the trailer tow parking lamp 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 connector
- Trailer tow parking lamp relay
- Trailer
PINPOINT TEST AA : 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 mounted on the bumper for signs of corrosion or damage. Repair or install a new trailer tow connector as required.
AA1 CHECK FOR VOLTAGE THROUGH THE TRAILER TOW CONNECTOR
- Place the headlamp switch in the PARKING LAMPS ON position.
- Measure the voltage between the trailer tow connector parking lamp voltage supply pins, circuit CAT11 (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
GO to AA2.
AA2 CHECK FOR VOLTAGE TO THE TRAILER TOW CONNECTOR
- Place the headlamp switch in the OFF position.
- Disconnect: Trailer Tow C4099.
- Place the headlamp switch in the PARKING LAMPS ON position.
- Measure the voltage between the trailer tow C4099-6, circuit CAT11 (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 AA3.
AA3 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.
- Measure the voltage between the trailer tow C4099-6, circuit CAT11 (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 AA4.
AA4 CHECK FOR VOLTAGE TO THE TRAILER TOW PARKING LAMP RELAY COIL
- Place the headlamp switch in the PARKING LAMPS ON position.
- Measure the voltage between the trailer tow parking lamp relay pin 1, circuit CLS30 (VT/WH), harness side and ground.
Is the voltage greater than 10 volts?
Yes
GO to AA5.
No
REPAIR circuit CLS30 (VT/WH) for an open. TEST the system for normal operation.
AA5 CHECK FOR VOLTAGE TO THE TRAILER TOW PARKING LAMP RELAY SWITCH
- Measure the voltage between the trailer tow parking lamp relay pin 3, circuit SBP38 (BN/RD), BJB (Battery Junction Box) face side and ground.
Is the voltage greater than 10 volts?
Yes
GO to AA7.
No
VERIFY the SJB (Smart Junction Box) fuse 38 (20A) is OK. If OK, GO to AA6. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Electrical Diagrams
AA6 CHECK THE TRAILER TOW PARKING LAMP RELAY VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
- Disconnect: SJB (Smart Junction Box) C2280D.
- Measure the resistance between the trailer tow parking lamp relay pin 3, circuit SBP38 (BN/RD), BJB (Battery Junction Box) face side and SJB (Smart Junction Box) C2280D-4, circuit SBP38 (BN/RD), harness side.
Is the resistance less than 5 ohms?
Yes
GO to AA8.
No
REPAIR circuit SBP38 (BN/RD) for an open. TEST the system for normal operation.
AA7 CHECK THE TRAILER TOW PARKING LAMP RELAY COIL GROUND CIRCUIT FOR AN OPEN
- Measure the voltage between the trailer tow parking lamp relay pin 3, circuit SBP38 (BN/RD), BJB (Battery Junction Box) face side and the trailer tow parking lamp relay pin 2, circuit GD120 (BK/GN), harness side and ground.
Is the voltage greater than 10 volts?
Yes
REPAIR circuit SBP38 (BN/RD) for an open. TEST the system for normal operation.
No
REPAIR circuit GD120 (BK/GN) for an open. TEST the system for normal operation.
AA8 CHECK FOR CORRECT SJB (Smart Junction Box) OPERATION
- Disconnect all the SJB (Smart Junction Box) connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SJB (Smart Junction Box) connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new SJB (Smart Junction Box). TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.