Wheel Speed Signal Conditioner Module

Wheel Speed Signal Conditioner Module:

The wheel speed signal conditioner module for the L81 application is only equipped on vehicles without antilock brakes. The wheel speed signal conditioner module is located behind the left front console trim panel, which is orange in color and similar dimensionally to a relay. The module harness is taped to the console harness.

Vehicle speed for misfire rough road detection on non-ABS vehicles is received from the right front wheel speed sensor. The wheel speed signal conditioner module is used to convert the A/C voltage of the sensor to a square wave. This is accomplished by pulse width modulating the vehicle speed output circuit to ground, which is pulled up to 12 volts through resistance in the ECM. The ECM interprets the square wave input as vehicle speed only to determine a rough road condition. NOTE: The ECM will receive true vehicle speed used in its diagnostic functions from the transmission over the Controller Area Network (CAN) based on the output speed sensor.