Output Speed Sensor Circuit Check (4WD): Notes

WARNING: This page does not describe the selected car, but rather 24 other vehicles, including the 1992 GMC Yukon, 1992 GMC Vandura Special, 1992 GMC Vandura, 1992 GMC Value Van, and 1992 GMC Suburban. However, it is still accessible from the selected car via links, so may be relevant.

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.

NOTE: Test numbers refer to test numbers on diagnostic chart.

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