bombay digital > boxster > projects > parking brake sensor switch

by Trygve Isaacson, ©2008

This article describes how to replace the parking brake sensor switch in a 986 Porsche Boxster. A faulty sensor switch will prevent raising or lowering the convertible top.

Sensors for Convertible Top Operation

There are two sensor switches in the Boxster that can go bad and prevent you from opening and closing the convertible top, or can cause your windows to not close all the way.

One sensor is often called "the microswitch", and it's located in the little hole where the convertible top latch hooks onto the front windshield frame. This sensor detects whether the latch is closed or open. When you open the latch, the side windows drop a couple of inches so that you can retract the convertible top without the windows being in contact with it. If the sensor starts to go bad, or the latch gets out of proper alignment, you may drive over a bump and suddenly find your windows rolling down a couple of inches or all the way, and you may be unable to roll them up until you fix the latch or cycle it a couple of times! The problem there is that the sensor thinks you have just unlatched the roof, and goes into window drop mode. The solution for this is either to replace the microswitch, or in the interim, pad it with a little piece of sticky-backed rubber or soft velcro, so that the hook presses it more firmly.

The other sensor is in the parking brake lever. The Boxster won't let you operate the convertible top (opening or closing it) while the car is moving. To enforce this, normally it requires that you engage the parking brake, and aren't moving above a certain very low speed as an extra check. There is a little sensor under the parking brake lever that detects whether it's engaged or not. If this sensor goes bad, when you engage the parking brake lever, the electronics don't know that you've done so. The PARK dash light won't light up, and you can't operate the convertible top. When the sensor starts to go, it may be intermittent so that repeated pulls on the brake lever will eventually get it to work. When it finally goes, you need to replace it. (Look in the owner's manual for the "emergency" procedures to raise or lower the convertible top manually.)

Part Number

The sensor switch is part number 996-613-112-01-M100. I got it from Pelican Parts for $4.50.

Removing the Forward and Center Consoles

So, here are the instructions for replacing the parking brake sensor switch. It's pretty easy and only requires a screwdriver with two Torx bits: T20 and T30.

First, remove the following snap-on trim pieces. These just slide or snap off.

1. Leather-covered trim piece on each side of the dash console. (Pull the forward edge off first.)

2. Carpet piece on each side of the dash console. (Slide forward, then pull the bottom edge off first.)

3. Brake lever side cover next to driver seat. (Pull the bottom edge off first.)

4. Leather-covered trim piece on each side of the center console rear storage bin. This is optional, but I think it makes it a little easier to lift the console out later. (Pull the bottom edge off first.)

Next, remove the dash console itself. It's attached with two T20 screws on each side. After you remove the screws, you can slide it out of the dash and away.

Remove the rubber mat from the rear storage bin. This will expose a T20 screw that holds down the plastic floor at the back. Remove the T20 screw and the plastic floor. You'll notice that you can now see the parking brake cable. The two big nuts there are for parking brake tension adjustment. If you ever need to tighten the parking brake, just adjust it here. This also exposes the second T20 screw you need to remove.

Next, remove the coin holder by sliding it straight up. This will expose another T20 screw. Remove it. That completes the three T20 screws holding down the back end of the center console.

Pull the shift lever and boot off. The lever is just a friction fit so it slides off if you pull hard enough. The boot then snaps off by prying the edges. Do the forward edge last and lift away. This should expose a T20 screw holding down the front of the console. Remove it. (See photo below.)

Pull the ash tray out. It just lifts up with a small amount of friction. This exposes the two T30 screws that help hold the switch plate down on the console. One of these screws also attaches the center console to the car. Remove them.

After removing the T30 screws, you can pull up the switch plate. You just sort of squeeze the side of it and pull it up. This exposes the final T20 screw holding holding the middle of the center console down.

Now that you have exposed the underside of the switch plate, remove the four plugs that connect the window and heated seat switches. Make a note of the plug colors so you can put them back in order. On my car, the white plugs were driver side and the brown plugs were passenger side. There are two other little wires with plugs you need to remove. One powers the ash tray light, and the other is for the rear storage tray alarm sensor. Now you can put the switch plate aside.

With all the securing screws removed, you can lift the center console out of the car. This takes some care and maneuvering. The key points you have to work around are the front (which tucks under the metal bracket where the forward console was mounted), the brake lever (which you have to lift the console around), and the rear (where the bottom edges of the console are a risk for scuffing the leather on the side of the seats). You just have to work it out carefully.

Installing the New Sensor Switch

Finally you are ready to replace the defective switch. It's located in a very tight spot at the base of the brake lever. If you look at the new one, you can see how it's oriented. There is a wire you need to unplug from the old one. The switch itself has a prong that pokes into the metal base with a one-way arrow-shaped plug that prevents it from backing out. You'll need to either pry it out until it breaks, or use a small knife to slice it off.

It's a bit difficult to slip the new switch in place. You just have to try different angles to get it to slip into place with the prong poking into the hole in the metal base.

Finishing Up

Test the new switch before putting anything back. Then just reverse the entire procedure, and you're done!