Output Speed Sensor Check

Output speed sensor check. 1992 Two wheel drive models except C/K:

Circuit Description:
The Vehicle Speed Sensor circuit consists of a magnetic induction type sensor, vehicle speed sensor buffer (DRAC) module and wiring. Gear teeth pressed on the outside diameter of the output carrier assembly induce an alternating current in the sensor. This current is transmitted to the DRAC where it is passed on to the PCM/TCM. The DRAC compensates for various axle ratios and converts the signal to a square wave for use by the speedometer, cruise control, and anti-lock systems.

Output Speed Sensor Diagnostic Chart:

Test Description:
Number(s) below refer to circled number(s) on the diagnostic chart.

1. Test one checks the vehicle speed sensor signal to the PCM/TCM.

2. Test two checks the vehicle speed sensor signal to the digital ratio adapter.

3. Test three directly verifies the vehicle speed sensor signal.


Diagnostic Aids:
Check all connections, especially at the transmission pass-thru connector.
If the input sensor is not operational at start up, this can cause the output sensor to read zero.
While code 24 is set the Scan Tool will display an RPM derived from input speed.