I'm not sure your cruise issue relates. I would have thought that all the controls for cruise on your car were electronic; Mitchell shows that when the brake pedal is pushed, +12V feeds the brake lights and the cruise ECU (this +12V to the cruise ECU cancels cruise control).

+12V from the brake light switch is also required to release the shift lock, so you can use that for a test as to whether or not the brake switch is working. (The test below assumes that the rest of your shift lock functionality is working fine - see this post).

- turn the key to the position II (Owner's manual is wrong; it says position I)
- try to take the transmission out of Park - it shouldn't
- now press and hold the brake pedal down
- now try to take the transmission out of Park - it should come out now

If the above test works, your brake switch is fine. If it doesn't, it could mean there are other issues with your shift lock release, otherwise it confirms your brake switch is likely the issue.

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David Armstrong - '86 240(350k km?), '93 940T(270k km), '89 240(parts source for others) near Toronto