Pinpoint Test Z: The Trailer Stop/Turn Lamp Is Inoperative
Trailer Lamps
Pinpoint Test Z: The Trailer Stop/Turn Lamp Is Inoperative
Refer to Wiring Diagrams Set 95, Trailer/Camper Adapter for schematic and connector information. Electrical Diagrams
Normal Operation
The Smart Junction Box (SJB) fuse 2 (15A) supplies voltage to both trailer tow stop/turn relays.
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, the voltage is routed to the trailer tow LH stop/turn relay and 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, the voltage is routed to the trailer tow RH stop/turn relay and the trailer tow connector.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Trailer tow connector
- Trailer tow stop/turn relay
- Trailer
- SJB (Smart Junction Box)
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.
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.
Z1 DETERMINE IF BOTH TRAILER STOP/TURN LAMPS ARE INOPERATIVE
- Ignition OFF.
- Determine if both trailer stop/turn lamps are inoperative.
Are both trailer stop/turn lamps inoperative?
Yes
VERIFY the SJB (Smart Junction Box) fuse 2 (15A) is OK. If OK, GO to Z2. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Electrical Diagrams
No
GO to Z3.
Z2 CHECK THE TRAILER TOW STOP/TURN RELAY VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
- Disconnect: Trailer Tow LH Stop/Turn Relay.
- Disconnect: SJB (Smart Junction Box) C2280D.
- Measure the resistance between the trailer tow LH stop/turn relay pin 3, circuit SBP02 (YE/RD), BJB (Battery Junction Box) face side and the SJB (Smart Junction Box) C2280D-13, circuit SBP02 (YE/RD), harness side.
Is the resistance less than 5 ohms?
Yes
GO to Z9.
No
REPAIR circuit SBP02 (YE/RD) for an open. Test the system for normal operation.
Z3 CHECK FOR VOLTAGE THROUGH THE TRAILER TOW CONNECTOR
- Connect: SJB (Smart Junction Box) C2280D.
- 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 Z4.
Z4 CHECK THE TRAILER TOW STOP/TURN CIRCUIT FOR VOLTAGE
- 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 Z5.
Z5 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 Z6.
Z6 CHECK FOR VOLTAGE TO THE TRAILER TOW STOP/TURN RELAY COIL
- For the trailer tow LH stop/turn relay, while applying the brake pedal, measure the voltage between the trailer tow LH stop/turn relay pin 1, circuit CLS18 (GY/BN), BJB (Battery Junction Box) face side and ground.
- For the trailer tow RH stop/turn relay, while applying the brake pedal, measure the voltage between the trailer tow RH stop/turn relay pin 1, circuit CLS19 (VT/OG), BJB (Battery Junction Box) face side and ground.
Is the voltage greater than 10 volts?
Yes
GO to Z7.
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.
Z7 CHECK FOR VOLTAGE TO THE TRAILER TOW STOP/TURN RELAY SWITCH
- For the trailer tow LH stop/turn relay, measure the voltage between the trailer tow LH stop/turn relay pin 3, circuit SBP02 (YE/RD), BJB (Battery Junction Box) face side and ground.
- For the trailer tow RH stop/turn relay, measure the voltage between the trailer tow RH stop/turn relay pin 3, circuit SBP02 (YE/RD), BJB (Battery Junction Box) face side and ground.
Is the voltage greater than 10 volts?
Yes
GO to Z8.
No
REPAIR circuit SBP02 (YE/RD) for an open. TEST the system for normal operation.
Z8 CHECK THE TRAILER TOW STOP/TURN RELAY COIL GROUND CIRCUIT FOR AN OPEN
- Measure the voltage between the trailer tow LH stop/turn relay pin 3, circuit SBP02 (YE/RD), BJB (Battery Junction Box) face side and the trailer tow LH stop/turn relay pin 2, circuit GD120 (BK/GN), BJB (Battery Junction Box) face side.
- Measure the voltage between the trailer tow RH stop/turn relay pin 3, circuit SBP02 (YE/RD), BJB (Battery Junction Box) face side and the trailer tow RH stop/turn relay pin 2, circuit GD120 (BK/GN), BJB (Battery Junction Box) 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.
Z9 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.