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DTC B124: Vehicle Speed Sensor (VSS) Circuit Problem: Intermittents

If an intermittent Code B124 is being set manipulate circuit No. 817 observing BCM data parameter BD60. See DATA DISPLAY PROCEDURE under DIAGNOSTIC MODES  under SELF-DIAGNOSTIC SYSTEM, for a list of BCM Data Parameters. If the failure is induced, the reading will jump from a normal value to 0 MPH.

During the time the failure is present, the continuous compressor at idle will be disabled.

NOTE: The following numbered steps refer to circled numbers on diagnostic chart. See Fig 1. For circuit identification, see Fig 2.
  1. If E024 is also set, then there is a VSS or ECM problem. See ECM DTC EO24: SPEED SENSOR CIRCUIT PROBLEM in SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
  2. Checks for speed signal at BCM.
  3. Isolates the loss of a valid speed signal to the BCM by checking for a circuit problem in circuit No. 817 or a faulty ECM.
NOTE: When all diagnosis and repairs are completed, clear codes and verify operation.
Fig 1: DTC B124: Vehicle Speed Sensor Circuit Problem Flow Chart
G00100642Courtesy of GENERAL MOTORS CORP.
Fig 2: DTC B124: Vehicle Speed Sensor Circuit Problem Flow Chart Circuit
G00100643Courtesy of GENERAL MOTORS CORP.