Pinpoint Test M: DTCs B2844 and U2472 - Vehicles With A Push Button Start System

Steering Column Switches

Pinpoint Test M: DTCs B2844 and U2472 - Vehicles With A Push Button Start System

Refer to Wiring Diagram Set 13, Power Distribution/SJB for schematic and connector information. Diagrams By Number

Normal Operation

The Remote Function Actuator (RFA) module provides battery voltage to the Smart Junction Box (SJB) along 3 circuits in the following combinations to achieve the desired ignition state:

- OFF

- ACC- Power on circuit CDC33 (VT/GN) to the SJB (Smart Junction Box)

- RUN- Power on circuit CDC01 (GN/VT) and CDC33 (VT/GN) to the SJB (Smart Junction Box) and Battery Junction Box (BJB)

- START- Power on circuit CDC35 (BU/WH) to the PCM and the One-Touch Integrated Start (OTIS) diode in the BJB (Battery Junction Box). From the OTIS (One-Touch Integrated Start) diode, the voltage is sent to the SJB (Smart Junction Box), the PCM and the starter relay in the BJB (Battery Junction Box) along circuit CE336 (GN/WH).

The SJB (Smart Junction Box) will provide circuit protection and distribute the voltage throughout the vehicle electrical system. The microprocessor internal to the SJB (Smart Junction Box) will translate the ignition state into a network message and broadcast the message over the Medium Speed Controller Area Network (MS-CAN) bus. The SJB (Smart Junction Box) continually monitors the voltage signals received from the RFA (Remote Function Actuator) module and will set a DTC if it receives an invalid combination of voltage signals.

- DTC B2844 (Ignition Fault)- The SJB (Smart Junction Box) monitors voltage on circuits CDC33 (VT/GN), CDC34 (WH/OG) and CDC35 (BU/WH) to determine the ignition switch position. If the SJB (Smart Junction Box) receives an invalid ignition switch state or cannot detect the ignition switch state during normal operation, DTC B2844 is set.

- DTC U2472 (Unexpected Ignition State)- If during the SJB (Smart Junction Box) on-demand self test, the SJB (Smart Junction Box) does not receive the ignition RUN signal or any ignition switch signal, DTC U2472 is set.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- Ignition switch

- SJB (Smart Junction Box)

PINPOINT TEST M : DTCs B2844 AND U2472 - VEHICLES WITH A PUSH BUTTON START SYSTEM

NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multi-meter probes.

M1 CHECK THE RFA (Remote Function Actuator) MODULE FOR DTCs

- Connect the scan tool.

- Ignition OFF.

- Enter the following diagnostic mode on the scan tool: Self Test- RFA (Remote Function Actuator) Module.

Are any DTCs retrieved?

Yes
CORRECT any RFA (Remote Function Actuator) module DTCs before diagnosing the SJB (Smart Junction Box).

REFER to the Master DTC Chart in Body Control Systems. Master DTC Index

No
GO to M2.

M2 CHECK THE IGNITION ACC CIRCUIT FOR AN OPEN

- Ignition OFF.

- Disconnect: RFA (Remote Function Actuator) Module C2153B.

- Disconnect: SJB (Smart Junction Box) C2280A.

- Measure the resistance between SJB (Smart Junction Box) C2280A-3, circuit CDC33 (VT/GN), harness side and RFA (Remote Function Actuator) module C2153B-4, circuit CDC33 (VT/GN), harness side.





Is the resistance less than 5 ohms?

Yes
GO to M3.

No
REPAIR circuit CDC33 (VT/GN). CARRY OUT an on-demand self test (required to clear certain DTCs). CORRECT any unresolved DTCs. CLEAR all DTCs. TEST the system for normal operation.

M3 CHECK THE IGNITION RUN CIRCUIT FOR AN OPEN

- Disconnect: SJB (Smart Junction Box) C2280B.

- Disconnect: Run/Start Relay.

- Measure the resistance between RFA (Remote Function Actuator) module C2153B-5, circuit CDC55 (BN/VT), harness side and run/start relay pin 2, circuit CDC55 (BN/VT).





Is the resistance less than 5 ohms?

Yes
GO to M4.

No
REPAIR circuit CDC55 (BN/VT). CARRY OUT an on-demand self test (required to clear certain DTCs). CORRECT any unresolved DTCs. CLEAR all DTCs. TEST the system for normal operation.

M4 CHECK THE PCM START CIRCUIT FOR AN OPEN

- Disconnect: SJB (Smart Junction Box) C2280E.

- Measure the resistance between OTIS (One-Touch Integrated Start) diode, circuit CE336 (GN/WH), output side and SJB (Smart Junction Box) C2280E-8, circuit CE336 (GN/WH), harness side.





Is the resistance less than 5 ohms?

Yes
GO to M5.

No
REPAIR circuit CE336 (GN/WH). CARRY OUT an on-demand self test (required to clear certain DTCs). CORRECT any unresolved DTCs. CLEAR all DTCs. TEST the system for normal operation.

M5 CHECK FOR CORRECT SJB (Smart Junction Box) OPERATION

- Disconnect all SJB (Smart Junction Box) connections.

- Check all SJB (Smart Junction Box) connections for:
- corrosion.
- pushed-out pins.
- spread terminals.


- Connect all SJB (Smart Junction Box) connections and make sure they are seated correctly.

- Operate the system and verify the concern is still present.

Is the concern still present?

Yes
INSTALL a new SJB (Smart Junction Box). CLEAR the DTCs. TEST the system for normal operation.

No
The system is operating correctly at this time. Concern may have been caused by a loose or corroded connector.