Car Corner
Brake Light - Shifter Problem

December 1, 2009
By Scott Lewis

This month I get to walk you through the steps it took to get my car working. This is something I would like to do more. Well, I would prefer it to be modifications to cars over repairs, but this is close enough.

The problem was with our 2001 Acura MDX. One day when leaving work the shifter would not come out of Park. I tried everything I could think of in the parking lot of work. I didn't have the ability to go through the fuses (my first thought) and needed to get the car home.

I READ THE OWNER"S MANUAL. I found the section on the shifter. It told me how to stick a flat blade screwdriver into a slot to release the shifter from Park. I did not have a screwdriver, but there were a pair of kiddie scissors in the glove compartment. The following day, while still using the scissors, I also noticed the brake lights did not come on. That means this is all related to the brakes in some way.

That Saturday it was time to get started. I e-mailed my mechanic in New York (I am in San Antonio, Texas) and he told me to look for a switch on the brake pedal, possibly inside the car or possibly on the other side of the firewall.

I crawled under the dash and I could see a bracket attached to the brake pedal. That bracket touched a switch mounted to another bracket. Perfect... I found the brake light switch. It was held in place with a jam nut. I unhooked the electrical plug, loosened the jam nut, and removed the brake light switch by hand.

I took it to the auto part store and they had one replacement in stock for $30.

Back home I replaced the brake light switch and... nothing happened. The shifter still did not come out of Park and the brake lights still did not work.

I e-mailed my mechanic. He told me to check the wiring in the plug and check all the fuses. I hooked up my voltmeter and got nothing out of all four wires going to the brake light switch. None of the fuses are labeled brake lights, so I have to pull and check every single fuse. There happen to be four locations where fuses are in the car. Two inside the interior and two under the hood.

I pulled every fuse and could not find a bad one anywhere.

I happen to e-mail my brother about the problem. He works in the parts department of a Kia dealership in New York. He checked with one of his technicians and his technician came up with a diagram of the car. Here's the conversation with my brother:

Brother: See the main fuse box on the passenger side?
Me: Yes.
Brother: It's not in there. See a box below the main fuse box?
Me: Yep.
Brother: That's not in there either. See ANOTHER box below the second box?
Me: O.K.
Brother: That's the one.

I opened this box and there where three gray cubes in there. This contained relays. There was one empty spot. My brother said the empty one was for a rear entertainment system. I don't have that in the car, so it was logical that it would be missing. They all looked exactly alike. My brother told me to pull the one toward the front of the car and on the driver's side. I pulled it out. My brother gave me a part number.

This time I went straight to the Acura dealer (figuring I might not find this at a traditional parts store). I tell the Acura parts man what I need (which is called the "Shift Lock Relay"). He comes back a few minutes later and has the part. Sure enough the number on the bag was the same number my brother gave me. Cost: $27.

I got home and plugged the relay in. I hooked up the new brake light switch and everything was working. I took out the new brake light switch and put in the old brake light switch. Yep, everything was working.

I returned the brake light switch and got my $30 back.

Now, my mechanic does not work on Acura's (he is heavily an American mechanic) and certainly does not have Acura service manuals on hand. Had I not mentioned this to my brother I might never have found that part.


In the end everything worked out. It only cost me $27 to fix the car.