Brake pedal/Starter interlock disconnect procedure

Kit Sullivan

Registered User
OK, here is the easy way:

Brake Pedal/ Starter Interlock By-Pass Procedure
(For 1990 model year Thunderbird and Cougar)​

Sometime around 1990 or so Ford Motor Company decided to “protect us from ourselves” and installed a starter interlock system on our cars preventing the starter from engaging until the brake pedal was depressed.
Unaware of this ‘feature’, many a car mechanic, car wash attendant, parking valet or other person driving your car has probably come up to you at one time or another and told you that your car won’t start. Telling them to step on the brake pedal solves the issue.
I am frequently reaching through the open driver-side window to crank the engine only to re-discover that I have to open the door and step on the pedal to start the car.
So, I had enough! A little tinkering with some simple hand tools, combined with about 15 minutes of my time on a Saturday morning and now it is all disconnected.
It is very easy, so follow along and we’ll do it together!

1. Disconnect the negative battery cable under the hood.

2. Use an 8mm socket to remove the three bolts from the lower trim panel below the steering column.
Set the trim panel aside.

3. Now, remove the three 8mm bolts holding the metal shield that is mounted directly behind the trim panel and remove that panel also.
Set this shield/panel aside.

4. There is now an open exposed area to the left of the steering column, and if you peer inside you will see a wiring harness attached to the top of the fuse panel.
Immediately to the right of that, and tucked up a little bit towards the
front is the Starter/Brake Pedal Interlock Relay and the associated
wiring.
The relay is attached to the inside of this opening and to the right on
the metal panel using a ‘christmas tree’ style fastener.
Carefully pry the relay off the panel and lower the whole assembly down out of the opening extending the wiring down so that you have easy access to work on it.

5. Remove the relay from the wiring harness. This is not strictly necessary since there is no current going thru the system with the key off and the battery disconnected, but it is a good habit to take as many precautions as you can when working around electrical wiring

6. There are four wires in this assembly: 2 large red wires with light blue tracers (stripes), a smaller green wire and a smaller purple wire. We are going to cut both of the red wires w/ blue tracers and join them together, eliminating the relay function from the wiring.

7. Once the 2 red wires w/ blue tracers are cut, strip about ½ “of insulation from the ends of both wires. Be sure to strip the wires that are coming from the wiring harness and not the ends of the wires still leading into the relay connector. Just leave the wires leading into the relay connector loose, as these are now going to be ‘dead’ and not connected to anything.
(I like to leave enough wiring on both ends of the cut so that I can re-connect the wiring back to ‘factory original’ if I one day decide to do so. This is a good precaution to take to preserve the future ‘collectable status’ of the car)

8. Use a blue butt-connector to join each of the two red wires/w blue tracers coming from the wiring harness together.

9. Reattach the relay to the relay connector.

10. Carefully tuck everything back up into the opening and attach the relay back into its original mounting location.

11. Reattach the metal shield.

12. Reattach the lower trim panel.

13. Clean up tools and put away.

14. Reconnect negative battery cable under the hood.

15. Start engine without stepping brake pedal.

16. Smile with satisfaction, knowing you just improved your ride a little!



Good luck, Kit Sullivan
 
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