B2844

Steering Column Switches

Pinpoint Test F: DTCs B2844 and U2472

Normal Operation

The Smart Junction Box (SJB) contains several microprocessors that monitor the voltage outputs from the ignition switch. The SJB (Smart Junction Box) use these inputs to determine ignition switch position and then send that information to various modules over the High Speed Controller Area Network (HS-CAN) bus. The ignition switch is designed so that only one output (ACC, RUN or START) is sent to the SJB (Smart Junction Box) at a time.

- DTC B2844 (Ignition Fault)- If the SJB (Smart Junction Box) receives an invalid ignition RUN input or cannot receive the ignition RUN input during normal operation, DTC B2844 is set.

- DTC U2472 (Unexpected Ignition State)- If the SJB (Smart Junction Box) does not receive the ignition RUN signal or receives conflicting ignition switch signals while performing an on-demand self test, 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 F : DTCs B2844 AND U2472

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

NOTE: Verify that battery voltage is 10 volts or greater.

F1 CHECK THE SJB (Smart Junction Box) DTCs

- Review the DTCs recorded during Inspection and Verification.

Is DTC B2A20 present?

Yes
GO to Pinpoint Test E. Pinpoint Test E: B2A20

No
GO to F2.

F2 CHECK THE IGNITION SWITCH PIDs

- Connect the scan tool.

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: DataLogger- SJB (Smart Junction Box).

- Monitor the following ignition switch PIDs while cycling the ignition switch through each position:
- ECU Derived Ignition State-OFF (IGN_O_ECU)
- ECU Derived Ignition State-ACC (IGN_A_ECU)
- ECU Derived Ignition State-RUN (IGN_R_ECU)
- ECU Derived Ignition State-START (IGN_S_ECU)


Does each PID display YES when the ignition switch is moved into the corresponding position and NO when the switch is moved to another position?

Yes
The condition is not present at this time. INSPECT SJB (Smart Junction Box) connectors C2280A and C2280B for corrosion, spread terminals and/or pushed-out pins. REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test.

No
If IGN_O_ECU displayed YES at all times, GO to Pinpoint Test A. Pinpoint Test A: No Power in All Ignition Switch Positions

If IGN_A_ECU and/or IGN_R_ECU displayed YES at all times, GO to F3.

If IGN_S_ECU displayed YES at all times, GO to Pinpoint Test E. Pinpoint Test E: B2A20

If IGN_A_ECU displayed NO at all times, GO to Pinpoint Test B. Pinpoint Test B: No Power in ACC

If IGN_R_ECU displayed NO at all times, GO to Pinpoint Test C. Pinpoint Test C: No Power in RUN

If IGN_S_ECU displayed NO at all times, GO to Pinpoint Test D. Pinpoint Test D: No Power in START

F3 ISOLATE THE SJB (Smart Junction Box) AND IGNITION CIRCUITS

- Disconnect: SJB (Smart Junction Box) C2280D.

- Disconnect: SJB (Smart Junction Box) C2280E.

- Measure the voltage between SJB (Smart Junction Box) C2280D-22, circuit CBP43 (GY) and ground.





- Measure the voltage between SJB (Smart Junction Box) C2280E-10, circuit CBP45 (YE) and ground.





Is any voltage present?

Yes
REPAIR the affected circuit(s). CLEAR the DTCs. REPEAT the self-test.

No
GO to F4.

F4 CHECK THE SJB (Smart Junction Box) RUN/ACC INPUTS FOR A SHORT TO VOLTAGE

- Disconnect: SJB (Smart Junction Box) C2280A.

- Disconnect: SJB (Smart Junction Box) C2280B.

- Measure the voltage between SJB (Smart Junction Box) C2280A-3, circuit CDC33 (VT/GN) and ground.





- Measure the voltage between SJB (Smart Junction Box) C2280B-45, circuit CDC34 (WH/OG) and ground.





Is any voltage present?

Yes
GO to F5.

No
GO to F6.

F5 CHECK THE IGNITION SWITCH FOR A SHORT TO VOLTAGE

- Disconnect: Ignition Switch C250.

- Measure the voltage between SJB (Smart Junction Box) C2280A-3, circuit CDC33 (VT/GN) and ground.





- Measure the voltage between SJB (Smart Junction Box) C2280B-45, circuit CDC34 (WH/OG) and ground.





Is any voltage present?

Yes
REPAIR the affected circuit(s). CLEAR the DTC. REPEAT the self-test.

No
INSTALL a new ignition switch. REFER to Ignition Switch Service and Repair. CLEAR the DTCs. REPEAT the self-test.

F6 CHECK FOR CORRECT SJB (Smart Junction Box) OPERATION

- Check SJB (Smart Junction Box) connectors C2280A, C2280B, C2280D and C2280E for:
- corrosion.
- pushed-out pins.
- spread terminal.


- Connect: SJB (Smart Junction Box) C2280A.

- Connect: SJB (Smart Junction Box) C2280B.

- Connect: SJB (Smart Junction Box) C2280D.

- Connect: SJB (Smart Junction Box) C2280E.

- Make sure the connectors are seated correctly, then 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 DTC. REPEAT the self-test.

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