Pinpoint Test M: DTCs B2844 And U2472 - Vehicles With A Push Button Start System
Steering Column Switches
Pinpoint Tests
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
- RUN - Power on circuit CDC01 (GN/VT) and CDC33 (VT/GN) to the SJB 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. From the OTIS diode, the voltage is sent to the SJB, the PCM and the starter relay in the BJB along circuit CE336 (GN/WH).
The SJB will provide circuit protection and distribute the voltage throughout the vehicle electrical system. The microprocessor internal to the SJB 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 continually monitors the voltage signals received from the RFA module and will set a DTC if it receives an invalid combination of voltage signals.
- DTC B2844 (Ignition Fault) - The SJB monitors voltage on circuits CDC33 (VT/GN), CDC34 (WH/OG) and CDC35 (BU/WH) to determine the ignition switch position. If the SJB 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 on-demand self test, the SJB 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
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.
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M1 CHECK THE RFA MODULE FOR DTCs
- Connect the scan tool.
- Ignition OFF.
- Enter the following diagnostic mode on the scan tool: Self Test - RFA Module.
- Are any DTCs retrieved?
Yes
CORRECT any RFA module DTCs before diagnosing the SJB.
REFER to the Master DTC Chart in Body Control Systems. Diagnostic Trouble Code (DTC) Chart
No
GO to M2.
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M2 CHECK THE IGNITION ACC CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: RFA Module C2153B.
- Disconnect: SJB C2280A.
- Measure the resistance between SJB C2280A-3, circuit CDC33 (VT/GN), harness side and RFA 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.
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M3 CHECK THE IGNITION RUN CIRCUIT FOR AN OPEN
- Disconnect: SJB C2280B.
- Disconnect: Run/Start Relay.
- Measure the resistance between RFA 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.
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M4 CHECK THE PCM START CIRCUIT FOR AN OPEN
- Disconnect: SJB C2280E.
- Measure the resistance between OTIS diode, circuit CE336 (GN/WH), output side and SJB
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.
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M5 CHECK FOR CORRECT SJB OPERATION
- Disconnect all SJB connections.
- Check all SJB connections for:
- corrosion.
- pushed-out pins.
- spread terminals.
- Connect all SJB 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. REFER to Body Control Systems. 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.
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