Pinpoint Test 6: DTCs B2844 And U2472 - Ignition Fault And Unexpected Ignition State

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PINPOINT TEST 6: DTCs B2844 AND U2472 - IGNITION FAULT AND UNEXPECTED IGNITION STATE

Normal Operation

When placed in ACC, RUN or START, the ignition switch sends voltage out to the smart junction box (SJB). Micro-processors in the SJB continuously monitor the ignition switch state. The ignition switch has 4 possible states:

- OFF
- ACC
- RUN
- START

When the ignition switch is placed in ACC, fused ignition voltage is sent to:

- SJB J2280a pin 3, along circuit (V/G).When the ignition switch is placed in RUN, fused ignition voltage is sent to:

- SJB J2280a pin 3, along circuit (V/G).
- SJB J2280e pin 1, along circuit (W/O).
- SJB J2280b pin 45, along circuit (W/O).
- Fuse 35 (10A) in the battery junction box (BJB) along circuit (W/O).When the ignition switch is placed in START, fused ignition voltage is sent to:

Non-Hybrid Vehicles
- Fuse 35 (10A) in the BJB along circuit (W/O).
- SJB J2280e pin 1, along circuit (W/O).
- SJB J2280b pin 45, along circuit (W/O).
- PCM 0140-175b pin 7, along circuit (L/W).
- BJB starter diode along circuit (L/W), then through the diode to:

- SJB J2280b pin 32, along circuit (L/BR).
- PCM 0140-175b pin 4, along circuit (L/BR).
- Transmission range (TR) sensor 0119-03 pin 4, along circuit (L/BR).

Hybrid Vehicles
- Fuse 35 (10A) in the BJB along circuit (W/O).
- SJB J2280e pin 1, along circuit (W/O).
- SJB J2280b pin 45, along circuit (W/O).
- PCM 0140-175b pin 21, along circuit (L/W).
- SJB J2280b pin 32, along circuit (L/W).

- SJB J2280b pin 32, along circuit (L/BR).
- PCM 0140-175b pin 4, along circuit (L/BR).
- Transmission range (TR) sensor 0119-03 pin 4, along circuit (L/BR).

- B2844 Ignition Fault - If the SJB receives an invalid ignition state or cannot detect the ignition switch state during normal operation, DTC B2844 is set.
- U2472 Unexpected Ignition State - If the SJB does not receive the ignition RUN signal, or any ignition switch signal, while carrying out an SJB self-test, DTC U2472 is set.

Possible Causes
- Wiring, terminals or connectors
- Ignition switch
- SJB

Diagnostic Procedure

CAUTION: 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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