Pinpoint Test AD: The Trailer Battery Charging Is Inoperative/Does Not Operate Correctly
Trailer Lamps
Pinpoint Test AD: The Trailer Battery Charging Is Inoperative/Does Not Operate Correctly
Normal Operation
The trailer battery charge relay coil receives voltage from the Smart Junction Box (SJB) fuse 44 (10A) when the ignition switch is in the RUN position. The Battery Junction Box (BJB) fuse 21 (30A) supplies voltage to the trailer battery charge relay switch side. When the trailer battery charge 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 battery charge relay
- Trailer
- SJB (Smart Junction Box)
PINPOINT TEST AD : THE TRAILER BATTERY CHARGING IS INOPERATIVE/DOES NOT OPERATE CORRECTLY
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.
AD1 CHECK FOR VOLTAGE THROUGH THE TRAILER TOW CONNECTOR (BATTERY CHARGE INOPERATIVE)
- Ignition ON.
- Measure the voltage between the trailer tow connector pin 5, circuit CAT14 (OG), component side and ground.
Is the voltage greater than 10 volts?
Yes
GO to AD8.
No
GO to AD2.
AD2 CHECK FOR VOLTAGE AT THE TRAILER TOW CONNECTOR (BATTERY CHARGE INOPERATIVE)
- Ignition OFF.
- Disconnect: Trailer Tow C4099.
- Ignition ON.
- Measure the voltage between the trailer tow C4099-5, circuit CAT14 (OG) 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 AD3.
AD3 CHECK THE TRAILER BATTERY CHARGE RELAY (INOPERATIVE)
- Ignition OFF.
- Disconnect: Trailer Battery Charge Relay.
- Substitute a known good relay.
- Ignition ON.
- Measure the voltage between the trailer tow C4099-5, circuit CAT14 (OG) and ground.
Is the voltage greater than 10 volts?
Yes
REMOVE the known good relay. INSTALL a new trailer battery charge relay. TEST the system for normal operation.
No
REMOVE the known good relay. GO to AD4.
AD4 CHECK FOR VOLTAGE TO THE TRAILER TOW BATTERY CHARGE RELAY
- Ignition OFF.
- Measure the voltage between the trailer battery charge relay pin 3, circuit SBB21 (GY/RD), BJB (Battery Junction Box) face side and ground.
Is the voltage greater than 10 volts?
Yes
GO to AD5.
No
VERIFY the BJB (Battery Junction Box) fuse 21 (30A) is OK. If OK, REPAIR circuit SBB21 (GY/RD) for an open. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short Electrical Diagrams.
AD5 CHECK FOR VOLTAGE TO THE TRAILER TOW BATTERY CHARGE RELAY USING THE RELAY GROUND PIN
- Measure the voltage between the trailer battery charge relay pin 3, circuit SBB21 (GY/RD), BJB (Battery Junction Box) face side and the trailer battery charge relay pin 2, circuit GD123 (BK/GY), BJB (Battery Junction Box) face side.
Is the voltage greater than 10 volts?
Yes
GO to AD6.
No
REPAIR circuit GD123 (BK/GY) for an open. TEST the system for normal operation.
AD6 CHECK FOR VOLTAGE TO THE TRAILER BATTERY CHARGE RELAY COIL (INOPERATIVE CONDITION)
- Ignition ON.
- Measure the voltage between the trailer battery charge relay pin 1, circuit CAT23 (GN/YE), BJB (Battery Junction Box) face side and ground.
Is the voltage greater than 10 volts?
Yes
REPAIR circuit CAT14 (OG) for an open. TEST the system for normal operation.
No
VERIFY the SJB (Smart Junction Box) fuse 44 (10A) is OK. If OK, GO to AD7. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short Electrical Diagrams.
AD7 CHECK THE TRAILER BATTERY CHARGE RELAY COIL VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: SJB (Smart Junction Box) C2280B.
- Measure the resistance between the trailer battery charge relay pin 1, circuit CAT23 (GN/YE), BJB (Battery Junction Box) face side and the SJB (Smart Junction Box) C2280B-6, circuit CAT23 (GN/YE), harness side.
Is the resistance less than 5 ohms?
Yes
GO to AD12.
No
REPAIR circuit CAT23 (GN/YE) for an open. TEST the system for normal operation.
AD8 CHECK FOR VOLTAGE AT THE TRAILER TOW CONNECTOR (BATTERY CHARGE ALWAYS ON)
- Ignition OFF.
- Measure the voltage between the trailer tow connector pin 5, circuit CAT14 (OG), component side and ground.
Is any voltage present?
Yes
GO to AD9.
No
The vehicle is operating correctly. SEND the trailer to an authorized camper/trailer repair facility.
AD9 CHECK THE TRAILER BATTERY CHARGE VOLTAGE SUPPLY CIRCUIT FOR A SHORT TO VOLTAGE
- Disconnect: Trailer Battery Charge Relay.
- Measure the voltage between the trailer tow connector pin 5, circuit CAT14 (OG), component side and ground.
Is any voltage present?
Yes
REPAIR circuit CAT14 (OG) for a short to voltage. TEST the system for normal operation.
No
GO to AD10.
AD10 CHECK FOR VOLTAGE TO THE TRAILER BATTERY CHARGE RELAY COIL (BATTERY CHARGE ALWAYS ON)
- Measure the voltage between the trailer battery charge relay pin 1, circuit CAT23 (GN/YE), BJB (Battery Junction Box) face side and ground.
Is any voltage present?
Yes
GO to AD11.
No
INSTALL a new trailer battery charge relay. TEST the system for normal operation.
AD11 CHECK THE TRAILER BATTERY CHARGE RELAY COIL SUPPLY CIRCUIT FOR A SHORT TO VOLTAGE
- Disconnect: SJB (Smart Junction Box) C2280B.
- Measure the voltage between the trailer battery charge relay pin 1, circuit CAT23 (GN/YE), BJB (Battery Junction Box) face side and ground.
Is any voltage present?
Yes
REPAIR circuit CAT23 (GN/YE) for a short to voltage. TEST the system for normal operation.
No
GO to AD12.
AD12 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.