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Pinpoint Test AC: The Trailer Battery Charging Is Inoperative/Does Not Operate Correctly




Trailer Lamps

Pinpoint Test AC: The Trailer Battery Charging Is Inoperative/Does Not Operate Correctly

Normal Operation

The trailer battery charge relay coil receives voltage from the Battery Junction Box (BJB) fuse 54 (5A) when the ignition is in RUN. The BJB (Battery Junction Box) fuse 21 (30A) supplies voltage to the trailer battery charge relay switch side at all times. The Body Control Module (BCM) controls the ground side for the battery charge relay coil.

The BCM (Body Control Module) provides ground for the trailer battery charge relay when the ignition is in RUN and the BCM (Body Control Module) determines that the battery voltage is not low. 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

- BCM (Body Control Module)

PINPOINT TEST AC : 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.

AC1 CHECK FOR VOLTAGE THROUGH THE TRAILER TOW CONNECTOR (BATTERY CHARGE INOPERATIVE)

- Start the engine.

- 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 AC2.
No
VERIFY the BJB (Battery Junction Box) fuse 21 (30A) is OK. If OK, GO to AC7. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short [1][2]Diagrams By Number.

AC2 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 AC3.
No
GO to AC5.

AC3 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 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 AC4.

AC4 CHECK FOR VOLTAGE TO THE TRAILER BATTERY CHARGE RELAY COIL (ALWAYS ON)

- Measure the voltage between the trailer battery charge relay pin 1, circuit CBB54 (VT/OG), BJB (Battery Junction Box) face side and ground.






Is any voltage present?

Yes
REFER to the Wiring Diagrams to identify the possible causes of the circuit short [1][2]Diagrams By Number. TEST the system for normal operation.
No
INSTALL a new trailer battery charge relay. TEST the system for normal operation.

AC5 CHECK FOR DTC B130C:14

- Review the DTCs recorded from the BCM (Body Control Module) self-test.

Is DTC B130C:14 present?

Yes
GO to AC6.
No
The vehicle is operating correctly. SEND the trailer to an authorized camper/trailer repair facility.

AC6 CHECK FOR VOLTAGE TO THE BCM (Body Control Module) (DTC B130C:14)

- Disconnect: BCM (Body Control Module) C2280F.

- Measure the voltage between the BCM (Body Control Module) C2280F-22, circuit CDC66 (BN/YE), harness side and ground.






Is the voltage greater than 10 volts?

Yes
GO to AC13.
No
REPAIR circuit CDC66 (BN/YE) for a short to ground. TEST the system for normal operation.

AC7 CHECK FOR VOLTAGE AT THE TRAILER TOW CONNECTOR (BATTERY CHARGE INOPERATIVE)

- Ignition OFF.

- Disconnect: Trailer Tow C439A.

- Ignition ON.

- Measure the voltage between the trailer tow C439A-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 AC8.

AC8 CHECK THE TRAILER BATTERY CHARGE RELAY (INOPERATIVE CONDITION)

- Ignition OFF.

- Disconnect: Trailer Battery Charge Relay.

- Substitute a known good relay.

- Ignition ON.

- Measure the voltage between the trailer tow C439A-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 AC9.

AC9 CHECK FOR VOLTAGE TO THE BATTERY CHARGE RELAY (SWITCH SIDE)

- Ignition OFF.

- Measure the voltage between the trailer battery charge relay pin 3, SBB21 (GY/RD), BJB (Battery Junction Box) face side and ground.






Is the voltage greater than 10 volts?

Yes
GO to AC10.
No
REPAIR circuit SBB21 (GY/RD) for an open. TEST the system for normal operation.

AC10 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 CBB54 (VT/OG), BJB (Battery Junction Box) face side and ground.






Is the voltage greater than 10 volts?

Yes
GO to AC11.
No
VERIFY the BJB (Battery Junction Box) fuse 54 (5A) is OK. If OK, REPAIR circuit CBB54 (VT/OG) 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 [1][2]Diagrams By Number.

AC11 CHECK THE BATTERY CHARGE RELAY COIL GROUND CONTROLLED CIRCUIT FOR A SHORT TO VOLTAGE

- Ignition OFF.

- Disconnect: Trailer Battery Charge Relay.

- Disconnect: BCM (Body Control Module) C2280F.

- Ignition ON.

- Measure the voltage between the BCM (Body Control Module) C2280F-22, circuit CDC66 (BN/YE), harness side and ground.






Is any voltage present?

Yes
REPAIR circuit CDC66 (BN/YE) for a short to voltage. TEST the system for normal operation. After the repair:

If no DTCs are present, TEST the system for normal operation.

If DTC U1000:00 is present, CLEAR the DTCs and REPEAT the self-test (required to enable the trailer battery charge relay control driver if DTC U1000:00 is present). TEST the system for normal operation.

If DTC U3000:49 is present, INSTALL a new BCM (Body Control Module). TEST the system for normal operation.
No
GO to AC12.

AC12 CHECK THE BATTERY CHARGE RELAY COIL GROUND CONTROLLED CIRCUIT FOR AN OPEN

- Ignition OFF.

- Connect: Trailer Battery Charge Relay.

- Ignition ON.

- Measure the voltage between the BCM (Body Control Module) C2280F-22, circuit CDC66 (BN/YE), harness side and ground.






Is the voltage greater than 10 volts?

Yes
GO to AC13.
No
REPAIR circuit CDC66 (BN/YE) for an open. TEST the system for normal operation.

AC13 CHECK FOR CORRECT BCM (Body Control Module) OPERATION

- Disconnect all the BCM (Body Control Module) connectors.

- Check for:
- corrosion

- damaged pins

- pushed-out pins


- Connect all the BCM (Body Control Module) 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 BCM (Body Control Module). 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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