Output Speed Sensor Circuit Check - 4WD Vehicles: Notes

Fig 1: Output Speed Sensor Circuit Diagram (4WD)

Courtesy of GENERAL MOTORS CORP.

The output sensor is a magnetic induction type. Gear teeth pressed on the outside diameter of the output carrier assembly induce an alternating current in the sensor. Since vehicle speed is taken from the transfer case on 4WD drive vehicles, the transmission output sensor signal on these units goes directly to the PCM/TCM. If input sensor is not operational at start up, it can cause the output sensor to read zero.

1. This test checks for a speed signal at the PCM/TCM.
2. This test checks the output sensor directly.