Pinpoint Test AD: The Trailer Battery Charging Is Inoperative/Does Not Operate Correctly
Trailer Lamps
Pinpoint Tests
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 33 (10A) when the ignition switch is in the RUN position. The Battery Junction Box (BJB) fuse 30 (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 tow connector
- Trailer battery charge relay
- Trailer
- SJB
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 mounted on the bumper for signs of corrosion or damage. Repair or install a new trailer tow connector as required.
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AD1 CHECK FOR VOLTAGE THROUGH THE TRAILER TOW CONNECTOR
- Ignition ON.
- Measure the voltage between the trailer tow connector battery charge voltage supply pin, circuit CAT14 (OG), component side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to AD8.
No
GO to AD2.
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AD2 CHECK FOR VOLTAGE AT THE TRAILER TOW CONNECTOR (INOPERATIVE)
- Ignition OFF.
- Disconnect: Trailer Tow C4099.
- Ignition ON.
- Measure the voltage between the trailer tow C4099-5, circuit CAT14 (OG), 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 AD3.
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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), harness side 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.
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AD4 CHECK FOR VOLTAGE TO THE TRAILER TOW BATTERY CHARGE RELAY SWITCH
- Ignition OFF.
- Measure the voltage between the trailer battery charge relay pin 5, circuit SBB30 (BN/RD), BJB face side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to AD5.
No
VERIFY the BJB fuse 30 (30A) is OK. If OK, REPAIR circuit SBB30 (BN/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. Diagrams By Number
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AD5 CHECK FOR VOLTAGE TO THE TRAILER BATTERY CHARGE RELAY COIL
- Ignition ON.
- Measure the voltage between the trailer battery charge relay pin 2, circuit CBP33 (WH/BN), BJB face side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to AD7.
No
VERIFY the SJB fuse 33 (10A) is OK. If OK, GO to AD6. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Diagrams By Number
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AD6 CHECK THE TRAILER TOW BATTERY CHARGE RELAY COIL VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: SJB C2280b.
- Measure the resistance between the trailer battery charge relay pin 2, circuit CBP33 (WH/BN), BJB face side and the SJB C2280b-6, circuit CBP33 (WH/BN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to AD12.
No
REPAIR circuit CBP33 (WH/BN) for an open. TEST the system for normal operation.
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AD7 CHECK FOR VOLTAGE TO THE TRAILER TOW BATTERY CHARGE RELAY USING THE RELAY GROUND PIN
- Ignition OFF.
- Measure the voltage between the trailer battery charge relay pin 5, circuit SBB30 (BN/RD), BJB face side and the trailer battery charge relay pin 1, circuit GD120 (BK/GN), BJB face side.
- Is the voltage greater than 10 volts?
Yes
REPAIR circuit CAT14 (OG) for an open. TEST the system for normal operation.
No
REPAIR circuit GD120 (BK/GN) for an open. TEST the system for normal operation.
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AD8 CHECK FOR VOLTAGE AT THE TRAILER TOW CONNECTOR (BATTERY CHARGE ALWAYS ON)
- Ignition OFF.
- Measure the voltage between the trailer tow connector battery charge voltage supply pin, 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.
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AD9 CHECK THE TRAILER TOW BATTERY CHARGE RELAY OUTPUT CIRCUIT FOR A SHORT TO VOLTAGE
- Disconnect: Trailer Battery Charge Relay.
- Measure the voltage between the trailer tow connector battery charge voltage supply pin, 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.
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AD10 CHECK THE TRAILER TOW BATTERY CHARGE RELAY COIL VOLTAGE SUPPLY CIRCUIT FOR A SHORT TO VOLTAGE
- Measure the voltage between the trailer battery charge relay pin 2, circuit CBP33 (WH/BN), BJB 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.
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AD11 ISOLATE THE SHORT TO VOLTAGE
- Disconnect: SJB C2280b.
- Measure the voltage between the trailer battery charge relay pin 2, circuit CBP33 (WH/BN), BJB face side and ground.
- Is any voltage present?
Yes
REPAIR circuit CBP33 (WH/BN) for a short to voltage. TEST the system for normal operation.
No
GO to AD12.
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AD12 CHECK FOR CORRECT SJB OPERATION
- Disconnect all the SJB connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SJB 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. REFER to Body Control Systems. 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.
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