GM Service Manual Online
For 1990-2009 cars only

Special Tools

EL-38522 Variable Signal Generator

For equivalent regional tools, refer to Special Tools.


Object Number: 1880312  Size: MF

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

  1. Disconnect the ISS/OSS wiring harness connector from the control solenoid (w/body and TCM) valve assembly.
  2. Using a terminal test kit, connect the EL-38522 generator to the affected ISS or OSS signal circuit on the control solenoid (w/body and TCM) valve assembly.
  3. 2.1. Set the EL-38522 generator Signal to 8 volts, the Frequency to 120 and the Percent Duty Cycle to 50.
    2.2. Ignition On, observe either the scan tool parameter ISS Signal or OSS Signal.
    2.3. The signal parameter should display between 100-400 RPM.
If the signal display is not in this range, the control solenoid (w/body and TCM) valve assembly is not reading the input signal correctly and is faulty.