2000 Ford Mustang, Shifter Interlock Erratic, Inop

This 2000 Ford Mustang came in with the complaint that the shifter interlock for the automatic transmission would not release properly and that it would have to be tried several times before it would release. I checked it and found that it required the brake pedal to be firmly pushed in order for it to work for me. I figured there was something wrong at the stoplight switch. If you click on the following pictures to enlarge them you will get a better view of the light green that was burnt at the switch connector.

A gentle tug and the wire pulled right out of the harness connector.

I disconnected the harness connector from the switch and detached the wiring from the brace where a push in connector had it secured.

With the tape and the push in connector removed I separated the wiring.

Then cut and spliced in the new repair harness connector. Part number 4020

For some reason the end caps are not available and I always make an effort to take it off the old one.

And then install it on the new connector.

I finished the job by wrapping the wires up with tape and securing the push pin connector to the harness and then securing the harness to the bracket. The customer did not realize that the stoplights were not working properly either. The brake pedal would have had to of been pushed quite firmly in order for the wire to move enough to work and by that time the vehicle would have been stopped. The result was a very delayed stoplight condition.

4 discussions on “2000 Ford Mustang, Shifter Interlock Erratic, Inop”

  1. I did this just like you explained but while I was fixing it, a wire made contacted with the metal that caused a spark now I can’t shift out of park. I checked all a fuses including 33 and 41. If you can help me I would appreciate it. Thanks

  2. Thanks,my wife’s 2004 Mustang has the same problem. Tonight,I will check the wiring and the switch. Excellent pictures and instructions. Jim, Manteca Calif.

  3. I had the same exact problem on my 2001. Thanks for the great photos and the steps. It worked exactly as you said. One hour later I was back on the road again. Thank you for sharing this information. Craig in Kansas City.

Share Your Experience: