Brake Light Switch Replacement DIY

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5chn3ll
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Brake Light Switch Replacement DIY

Post by 5chn3ll » Tue Jun 19, 2018 10:51 am

This is one of the more common 996 electrical issues. As the plunger switch that determines whether the brakes are engaged begins to fail, the car will occasionally display simultaneous ABS and PSM warning lights.

This is NOT equivalent to switching PSM off using the dash switch (if your car is so equipped). When both lights are lit, your ABS pump is not functional and none of the ABS-related stability controls will work. You probably want to be very careful when driving the car in this state.

Step 1: Acquire the new switch from your favorite Porsche parts site. Pelican lists the switch for my car as:
Brake Light Switch at Pedal,
Item# 996-613-113-02-M100

01.jpg

The brake pedal switch is even higher up under the dash than the clutch pedal (cruise control cancel) switch. Grab and pop out the dash vent duct from below the dash – this GREATLY improves visibility when you are upside-down under the dash.

02.jpg

The next photo shows the view from the floor looking up under the dash. To the left (in the red circle) is the cruise control cancel switch for the clutch pedal. The switch circled in yellow is the brake light switch; the yellow arrow points to the place where this switch is mounted.
To remove the switch, turn the body of the switch one-quarter turn. The DIY guides I’ve seen elsewhere specify a direction (clockwise/counterclockwise), but turning in either direction will work.

Hints:
1) It may help to depress the brake pedal slightly during removal.
2) Push the switch inward - against the mounting plate - and then turn it.


03.jpg

Once the switch is hanging loose below the dash, use your tool of choice to unclip the retaining clips. NOTE: there are two clips – one on each side – so you want to do your unclipping when you have already removed the switch. Trying to do this in situ will drive you crazy.

04.jpg

Plug your new switch into the electrical connecter. Notice that the switch is keyed – it will only fit into the connector one way. It’s probably easier to just try both orientations when you’re under the dash than trying to see which way is correct.

05.jpg

Once you have the new switch plugged into the electrical connector, insert the switch back into the mounting hole. Align the “ears” of the switch with the slots in the mounting hole, depress the brake pedal, push it all the way home, and turn it one-quarter turn to secure in place.


08.jpg


This part of the process is largely under-documented. NOTICE that the new switch plunger is probably longer
than the one you've removed.

09.jpg

The plunger has an internal ratcheting adjustment. FOR BEST RESULTS,
depress the brake pedal, install the new switch, and then gently release the brake pedal. You'll hear
the switch ratchet into the correct position.

If you push the switch plunger in too far, just pull firmly on it and it will extend back out.

IF YOU PUSH the plunger in too far and do not rectify this before installation, your brake lights will be stuck in the "on" position.



If you have difficulty applying enough torque to the switch body, you can use a zip tie as a handle (nod to Roadkill Garage for this Ziptie Moment ™ ). Use the old switch as a pattern for your zip tie handle…

06.jpg

If you get the new switch and the old switch mixed up, check the stamping on the plastic switch body. There are two 2-digit numbers; the second 2-digit number is the year the part was produced. The stock switch was stamped “98” and the replacement was stamped “16.”

One final hint: When you un-bag the new switch, take a minute to mark it with a Sharpie so you know the new switch from the old. You can always check the date code as shown above, but it’s a lot easier to mark the new one with some obvious markings so you don’t have to try to make those numbers out while upside down under the dashboard.

07.jpg

Finally, get your assistant (or telescoping paint roller pole) and verify that the lights work as expected. If you do not have an assistant or your shaft is too short, back up to a wall or pull into your garage to verify light operation.
10.jpg
This is an easy repair, with the caveat that you’d better be somewhat flexible. I’m 6’2”, 250ish, but relatively limber…and I found it rather uncomfortable. It’s good training for replacing that ignition switch…

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32wildbilly
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Re: Brake Light Switch Replacement DIY

Post by 32wildbilly » Tue Jun 19, 2018 11:35 am

5chn3ll wrote:
Tue Jun 19, 2018 10:51 am
This is one of the more common 996 electrical issues. As the plunger switch that determines whether the brakes are engaged begins to fail, the car will occasionally display simultaneous ABS and PSM warning lights.
This is NOT equivalent to switching PSM off using the dash switch (if your car is so equipped). When both lights are lit, your ABS pump is not functional and none of the ABS-related stability controls will work. You probably want to be very careful when driving the car in this state.

Once the switch is hanging loose below the dash, use your tool of choice to unclip the retaining clips. NOTE: there are two clips – one on each side – so you want to do your unclipping when you have already removed the switch. Trying to do this in situ will drive you crazy.

This is an easy repair, with the caveat that you’d better be somewhat flexible. I’m 6’2”, 250ish, but relatively limber…and I found it rather uncomfortable. It’s good training for replacing that ignition switch…
Nicely done. My only problem is the tool you used to unclip the the retainers. An exacto knife will cut the Hell out of you if it slips! Ask me how I know. I can show the scar. Got to be something better?

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sweet victory
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Re: Brake Light Switch Replacement DIY

Post by sweet victory » Tue Jun 19, 2018 12:52 pm

I think I used a plastic panel trim popper. Pretty safe. Just don't swallow it or stick into any of your own orifices.


I had to do this when I still lived in an apartment complex in Irvine. Other tenants we're quiet perplexed by a person working on his own car, much less seeing me looking like I'm crab walking in and out of the car cussing under my breath. :lol:
2001 996 C2 Aero

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5chn3ll
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Re: Brake Light Switch Replacement DIY

Post by 5chn3ll » Tue Jun 19, 2018 1:06 pm

My advice is to uninstall the switch, let it hang under the dash while you get comfortable and choose the tool(s) of choice.

If I had still been upside down under the dash looking upward, a hobby knife would probably not have been my first choice either. :D
32wildbilly wrote:
Tue Jun 19, 2018 11:35 am
Nicely done. My only problem is the tool you used to unclip the the retainers. An exacto knife will cut the Hell out of you if it slips! Ask me how I know. I can show the scar. Got to be something better?

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32wildbilly
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Re: Brake Light Switch Replacement DIY

Post by 32wildbilly » Tue Jun 19, 2018 1:44 pm

5chn3ll wrote:
Tue Jun 19, 2018 1:06 pm
My advice is to uninstall the switch, let it hang under the dash while you get comfortable and choose the tool(s) of choice.

If I had still been upside down under the dash looking upward, a hobby knife would probably not have been my first choice either. :D
32wildbilly wrote:
Tue Jun 19, 2018 11:35 am
Nicely done. My only problem is the tool you used to unclip the the retainers. An exacto knife will cut the Hell out of you if it slips! Ask me how I know. I can show the scar. Got to be something better?
Still the placement of your one finger could be in the path of an uncontrolled slip. Nice thing about those cuts is they don't really hurt until later but they really do bleed.

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Re: Brake Light Switch Replacement DIY

Post by 5chn3ll » Tue Jun 19, 2018 2:22 pm

Nothing a dollop of your favorite cyanoacrylate can't fix...

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32wildbilly
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Re: Brake Light Switch Replacement DIY

Post by 32wildbilly » Tue Jun 19, 2018 5:41 pm

5chn3ll wrote:
Tue Jun 19, 2018 2:22 pm
Nothing a dollop of your favorite cyanoacrylate can't fix...
I've always struggled with using Super Glue to stick my skin back together, but I know its used for that purpose.

I would mention your "short shaft" comment but I shall refrain.

Still a very good writeup.

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Re: Brake Light Switch Replacement DIY

Post by b3freak » Tue Jun 19, 2018 6:57 pm

Nice IMS ring you have on your finger there Schnelly. Is it a single or dual row? :D
2002 Porsche 996 Carrera - bare bones basic, but still a blast to drive! Heck, I don't even have PSM on it. Ha!

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Re: Brake Light Switch Replacement DIY

Post by 5chn3ll » Mon Jun 25, 2018 8:40 am

It's a single-row, tungsten carbide retrofit...one of the few things I own that I can't inadvertently destroy.
b3freak wrote:
Tue Jun 19, 2018 6:57 pm
Nice IMS ring you have on your finger there Schnelly. Is it a single or dual row? :D

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Re: Brake Light Switch Replacement DIY

Post by 5chn3ll » Tue Jun 26, 2018 8:24 am

Good news: the new brake light switch has banished the intermittent ABS/PSM fault as hoped. Three days of driving, no lights yet.

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