One Or More Speed Related Functions Do Not Operate Properly

WARNING: This page is about a different car, the 1994 Oldsmobile Cutlass Ciera. However, it is still accessible from the selected car via links, so may be relevant.

Identify vehicle speed input terminal(s) of inoperative component(s). Disconnect inoperative component's connector. Ignition switch in RUN. Measure voltage at vehicle speed input terminal of inoperative component's connector.

NOTE: If more than one or all components do not operate, measure at any inoperative component's connector.

If 5 volts or greater (less than battery voltage) are measured, go to step 2). If voltage is not as specified, check circuit 389 for an open or short to ground of voltage. If okay, check modules for internal shorts or battery voltage at vehicle speed input terminals.

2) Measure voltage at connector terminal used above while slowly rotating a drive wheel by hand. If voltage does not vary from less than 1 volt to more than 2.5 volts, go to step 3). If voltage is as specified, speed signal is reaching component. Check for good connector contact at component. If okay, replace component.

3) Reconnect connectors of suspect component(s). Disconnect PCM connector C2 on VIN 4, or C3 on VIN M. Measure voltage at connector B8 on VIN 4, or D10 on VIN M. If 5 volts or more are not measured, repair open in circuit 389. If 5 volts or more are measured, check PCM connector for good contact. If contact is okay, replace PCM.