Special Tools

J 38522  Variable Signal Generator

Fig 1: J 38522

Courtesy of GENERAL MOTORS CORP.

The purpose of this test is to provide a simulated output speed sensor (OSS) signal to the control solenoid (w/body and TCM) valve assembly OSS input circuits.

1. Disconnect the OSS wiring harness connector from the OSS assembly.
2. Using a terminal test kit, connect the red lead of J 38522  to the OSS signal circuit terminal B and the black lead to the OSS supply voltage circuit terminal A.
   1. Set the J 38522  Signal to 8 volts, the Frequency to 120 and the Percent Duty Cycle to 50.
   2. With the ignition ON, observe the scan tool parameter OSS Signal.
   3. The signal parameter should display between 100-400 RPM.

• If the signal display is not in this range, test the OSS signal and supply voltage circuits for an open/high resistance, short to ground, or short to voltage. If the circuits test normal, the control solenoid (w/body and TCM) valve assembly is not reading the input signal correctly and is faulty.