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P codepowertrainMedium severity

P2747Intermediate Shaft Speed Sensor "B" Circuit No Signal

The transmission control module is receiving no signal at all from intermediate shaft speed sensor "B" when the shaft should be turning.

Definition

The TCM expects pulses from intermediate shaft speed sensor B whenever the vehicle is moving and the transmission's internal shafts are rotating. P2747 sets when the sensor produces no signal while the input and output speed sensors confirm rotation. Because the TCM loses one of its ratio-verification inputs, it typically defaults to limp mode with fixed or limited gears, harsh engagements, and an illuminated MIL.

Common causes

  • Failed intermediate shaft speed sensor B
  • Open circuit in the sensor signal wiring
  • Disconnected, corroded, or fluid-contaminated connector
  • No supply voltage or ground to the sensor (Hall-effect types)
  • Sheared or severely damaged tone ring
  • Failed TCM input (rare)

Common misdiagnoses

  • Valve body or solenoid pack replaced for a dead sensor
  • Transmission overhauled when a connector had backed out
  • Wrong shaft speed sensor replaced
  • TCM replaced without checking sensor power and ground

Troubleshooting steps

  1. 1.Confirm the dead signal on a scan tool

    Drive the vehicle while graphing all shaft speed PIDs; sensor B reading zero while input/output speeds are normal confirms the no-signal condition.

  2. 2.Check the connector first

    Verify the sensor connector is fully latched and free of transmission fluid, corrosion, or bent pins, since a backed-out connector is a common and cheap find.

  3. 3.Verify sensor supply and ground

    With key on, confirm the specified reference voltage (often 5 or 12 volts) and a good ground at the sensor connector.

  4. 4.Test the signal circuit to the TCM

    Check the signal wire for opens and shorts between the sensor connector and TCM connector using the wiring diagram.

  5. 5.Replace the sensor and re-test

    If power, ground, and wiring are good, replace sensor B, clear codes, and verify a live proportional signal on a road test.

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