2000 Boxster-S microswitch mystery

[rambo]

Hi all;

I have owned and driven Porsches continuously since 1977. I special-ordered my present Boxster-S in 2000; this is my 7th Porsche and – niggling problems aside – still my favorite one so far. It only has 20K miles on it, but I have had to replace trunk cables, tires (naturally!), both horns, and some other top and electronic components etc. I’d had similar failures with my regular Boxster, so I wasn’t totally surprised. Anyway, I almost literally turned every bolt on several of my previous Porsches and I am an engineer by trade, so I am not often stumped by them anymore but this time, I am very much so.

Failure: The top failed to go down, raising only the drivers side of the clamshell (and slightly bending it before I noticed). I powered the clamshell back into the down position with the top up, and referred to Bentley’s manual. The right side drive cable turned out to be broken, so I replaced both sides.

Now, the top is inoperable. The windows do not move when I unlatch the center top lock (but work fine otherwise), the yellow top light on the dashboard stays lit at all times, and the top up/down switch does nothing. However, I can put 12V directly across the top motor and drive the entire mechanism manually and it works fine.

Where the heck are the top microswitches??!!!

I did print out and go through the “Micro switch trouble shooting sequence” that was very kindly provided elsewhere in these forums, failing at #6. I had already metered out the micro switches in the front top lock and both worked fine, as did the handbrake switch. These are the only two micro switch locations I can find. There is no –repeat – no – switch located on or near the top motor itself.

There is a vague reference in Bentley’s to a microswitch on the right transmission, but I SWEAR that there is no microswitch anywhere near the passenger side transmission. I even took both of the stupid transmissions back out and checked all over the place for wires that could’ve led to this mysterious switch or another one. Nothing.

Finally, there does seem to be a small (~1” x 1”) plastic housing at the drivers side left shoulder, mounted just behind the base of the roll bar. This assembly contains two wires that enter it from the bottom and which are terminated as two pins that stick up vertically inside this small housing, looking as though they should mate with two female sockets on some sort of plug. However, that housing box is simply covered with a snap-on lid that has a plastic actuator-looking thingie molded into it. There is no switch, or even a piece of metal that could serve to short across the two pins and complete a circuit.

Nevertheless, thinking that perhaps the switch had just "disappeared" even though I was nowhere close to it in my cable replacement process, I jumpered across these pins at a couple of points in the top up/down process, which did nothing – no affect on the dash light, on the operation of the other switches, or of the top.

In sum, the drive cables, drive motor, and entire top and clamshell mechanisms are proven to work fine, and the top lock and handbrake switches (and fuses) are fine, but the control circuitry is somehow screwed up. I do not have enough info to troubleshoot the bowels of the top control relay and assume that it is too expensive to swap on a whim.

Can anyone help me?

[1schoir]

...

Finally, there does seem to be a small (~1” x 1”) plastic housing at the drivers side left shoulder, mounted just behind the base of the roll bar. This assembly contains two wires that enter it from the bottom and which are terminated as two pins that stick up vertically inside this small housing, looking as though they should mate with two female sockets on some sort of plug. However, that housing box is simply covered with a snap-on lid that has a plastic actuator-looking thingie molded into it. There is no switch, or even a piece of metal that could serve to short across the two pins and complete a circuit.

...

Rambo:

What you are referring to in this paragraph is most likely the connector for the rear window defroster that is found (AFAIK) on all Boxsters, even the ones with plastic windows. It's used in those instances to power the defroster grid in the hardtop. ;)

Regards, Maurice.

[1schoir]

Hi all;

I have owned and driven Porsches continuously since 1977. I special-ordered my present Boxster-S in 2000; this is my 7th Porsche and – niggling problems aside – still my favorite one so far. It only has 20K miles on it, but I have had to replace trunk cables, tires (naturally!), both horns, and some other top and electronic components etc. I’d had similar failures with my regular Boxster, so I wasn’t totally surprised. Anyway, I almost literally turned every bolt on several of my previous Porsches and I am an engineer by trade, so I am not often stumped by them anymore but this time, I am very much so.

Failure: The top failed to go down, raising only the drivers side of the clamshell (and slightly bending it before I noticed). I powered the clamshell back into the down position with the top up, and referred to Bentley’s manual. The right side drive cable turned out to be broken, so I replaced both sides.

Now, the top is inoperable. The windows do not move when I unlatch the center top lock (but work fine otherwise), the yellow top light on the dashboard stays lit at all times, and the top up/down switch does nothing. However, I can put 12V directly across the top motor and drive the entire mechanism manually and it works fine.

Where the heck are the top microswitches??!!!

I did print out and go through the “Micro switch trouble shooting sequence” that was very kindly provided elsewhere in these forums, failing at #6. I had already metered out the micro switches in the front top lock and both worked fine, as did the handbrake switch. These are the only two micro switch locations I can find. There is no –repeat – no – switch located on or near the top motor itself.

There is a vague reference in Bentley’s to a microswitch on the right transmission, but I SWEAR that there is no microswitch anywhere near the passenger side transmission. I even took both of the stupid transmissions back out and checked all over the place for wires that could’ve led to this mysterious switch or another one. Nothing.

Finally, there does seem to be a small (~1” x 1”) plastic housing at the drivers side left shoulder, mounted just behind the base of the roll bar. This assembly contains two wires that enter it from the bottom and which are terminated as two pins that stick up vertically inside this small housing, looking as though they should mate with two female sockets on some sort of plug. However, that housing box is simply covered with a snap-on lid that has a plastic actuator-looking thingie molded into it. There is no switch, or even a piece of metal that could serve to short across the two pins and complete a circuit.

Nevertheless, thinking that perhaps the switch had just "disappeared" even though I was nowhere close to it in my cable replacement process, I jumpered across these pins at a couple of points in the top up/down process, which did nothing – no affect on the dash light, on the operation of the other switches, or of the top.

In sum, the drive cables, drive motor, and entire top and clamshell mechanisms are proven to work fine, and the top lock and handbrake switches (and fuses) are fine, but the control circuitry is somehow screwed up. I do not have enough info to troubleshoot the bowels of the top control relay and assume that it is too expensive to swap on a whim.

Can anyone help me?

Rambo:

It's possible that one of the two microswitches in the convertible top latch receptacle is intermittent or has a hairline crack. A hairline crack in one of these microswitches has been known to connect and disconnect according to the ambient temperature... As the temperature rose, the connection was made, as the temperature dropped the connection was broken.

Here is a link to a documented instance:

http://www.renntech.org/forums/index.php?s...c=10458&hl=

The reason I think you should double check this again is because you stated that when you unlatched the top, the windows did not drop. The most likely suspect in that case is one of the aforementioned two microswitches. The other possibility is the main (double) relay.

It also wouldn't cost anything to take out the double relay from the relay carrier (at the driver's side kick panel) and push it back on a few times. That will sometimes clean off trace amounts of corrosion and re-energize the relay. While you have it off, rap it on a hard surface a few times (similar to when people used to tap their cigarette packs).

Also, although you mentioned that the handbrake microswitch tested out fine, it wasn't clear from your post whether the Handbrake idiot light on the dash actually lit up.

Regards, Maurice.

[rambo]

Hi Maurice;

I have seen your name on many of the postings on this site and as with many other people, I very much appreciate your efforts on behalf of your fellow Porsche guys...

Anyway, I'm sorry I wasn't clear, but the handbrake light does indeed work properly and I had, in fact, already followed your suggestions on the double relay (multiple taps, unplugs, re=plugs, etc.) but "no joy" as they say in car repair manuals written in England.

As I mentioned, I have been pretty much all over this forum, in my attempts to not ask a question that had already been answered, and had already seen the post concerning the top lock microswitches but discounted the notion because I'd already checked them pretty thoroughly. The car is always kept in a heated garage and the weather has been mild, so there is not a lot of opportunity for temperature change-related mischief.

Per your suggestion, I will check them out again at lunch time today and will also try to activate them manually to see if the top magically starts to work. Honestly, I don't have much hope, though...

Do you have ANY idea where I could look for top switches for a 2000 Boxster S? Again, none visible (and no extra wires) on the top motor, no switches or wires on or near either transmission, nothing that I can find on or near the clamshell tracks, etc. The wires I mentioned earlier near the drivers left shoulder was the only slight hope, but per your comments this is likely the defogger connection. ( I will also verify this today.)

This is 'typical' of Porsche, to change the design sort of whimsically, and it will drive me nuts if I don't figure it out. So close to success, and yet still so far...

thanks again for all of your help to myself and others,

Rob

[atta]

Do you have ANY idea where I could look for top switches for a 2000 Boxster S? Again, none visible (and no extra wires) on the top motor, no switches or wires on or near either transmission, nothing that I can find on or near the clamshell tracks, etc. The wires I mentioned earlier near the drivers left shoulder was the only slight hope, but per your comments this is likely the defogger connection. ( I will also verify this today.)

Hi.

It's on the *left* (drivers) side transmission. I know the manual says it's on the right side, but it is in fact on the left side. Both the switch on top of the motor and the b-pilar switch is now located inside the transmission (3-pin). I have marked the location of the plug on the attached picture. Hope this helps. :)

Atle

[rambo]

Hi;

First, thanks very much for your trouble! I have to say that I looked the transmissions over pretty well last time I pulled them, and there were certainly no wires connected to them or anywhere inside their enclosure area, but your advice is the only lead that I have right now and - well, the switches have gotta be somewhere, right?

Anyway, I will go pull the left transmission for the third time, and check again. I will let you know what I find out in an hour or two and I really, really appreciate your help.

Rob

[rambo]

Atle;

Well, you nailed it!

I swear that I had looked at both transmissions, but evidently not well enough. This microswitch was integrated with the LEFT transmission so well that I missed it. I must've inadvertently unplugged it when I removed that transmission.

For anyone else's future reference, this is a very small connector. With a casual look, it is very easy to miss. It has very small black shrink-wrapped wires and a tiny black plug. The wires only have an inch or two of slack, so it is tricky to get them plugged back in.

This is such a classic Porsche quirk. I bet that just about every Porsche ever built has a few similar non-standard/oddball parts or configurations ready to drive their owners nuts. Just another reason to love 'em, I guess.

Anyway, everything now works great. Thanks to both you and to Maurice for your efforts to help me out. FWIW I will be shown as a contributing member shortly, this is a great resource and well worth supporting.

Again, my sincere thanks.

Rob

[1schoir]

Atle;

Well, you nailed it!

I swear that I had looked at both transmissions, but evidently not well enough. This microswitch was integrated with the LEFT transmission so well that I missed it. I must've inadvertently unplugged it when I removed that transmission.

For anyone else's future reference, this is a very small connector. With a casual look, it is very easy to miss. It has very small black shrink-wrapped wires and a tiny black plug. The wires only have an inch or two of slack, so it is tricky to get them plugged back in.

This is such a classic Porsche quirk. I bet that just about every Porsche ever built has a few similar non-standard/oddball parts or configurations ready to drive their owners nuts. Just another reason to love 'em, I guess.

Anyway, everything now works great. Thanks to both you and to Maurice for your efforts to help me out. FWIW I will be shown as a contributing member shortly, this is a great resource and well worth supporting.

Again, my sincere thanks.

Rob

Rob:

Great news! Thanks for reporting back. Your posts and Atle's photo and tip will, I am sure, prove invaluable down the road.

Regards, Maurice.

[atta]

Great news, and thanks for reporting back. :renntech:

A.

[Tool Pants]

Green thing is the switch on the transmission.

[996noob]

Hope it's okay that I've revived this thread after 4 years!

Anyway, I have a 986 Boxster that seems like the transmissions continue to turn and each side makes a repetitive loud clicking noise, left click then right click sound in quick succession, then it happens again then once again, if you keep pushing the close switch. Could it be the limit switch in the left ransmission is faulty? There is also a warning light on the dash for the convertible top.