Top not working on 98 Boxster / any diagnostic steps available?

911Senior · 01-07-2011, 02:14 PM

The last few months the operation of the top has become temperamental, working when it wanted to. Now, it will not operate at all and the dash indicator light is glowing whenever the key is on. Are there any diagnostic steps available to figure out what the electrical problem is? Or the most probable cause of the failure. Thanks!

JFP in PA · 01-07-2011, 02:34 PM

Yes, and it is going to sound strange: Check the switch on your hand brake. The top will not operate unless it gets a signal that the parking brake is engaged; if the switch goes bad, top won't work...........

Wayne 962 · Wayne 962's Garage

I agree, the handbrake switch is the number one failure here, and also the easiest fix. The top won't operate if the car is going more than about 15 mph, and the handbrake has to be engaged too. I've always thought this was a dumb design - the car doesn't remind you with a display message to pull the handbrake. Many times I'm sitting there thinking "why isn't this working and then 2 seconds later I remember about the brake".

If it's not the handbrake switch, it may be the top relay / controller located on the lower left kick panel.

If the dash indicator lamp is on, then the roof may not be fully parked. Do you have issues with rolling up the windows too?

-Wayne

911Senior · 01-07-2011, 04:04 PM

The hand brake is engaged and indicator dash light is on. Would that also mean the switch is working properly?
The windows are working properly, but do not drop when the center top latch is released.
Is the location of the top operation relay marked somewhere? I have not yet check the owners manual.
Thanks for the guidance.

thstone · 01-07-2011, 06:14 PM

If the windows don't drop when the center top latch is released, it is probably the top microswitch in the windshield.

There are actually two switches in one - if you stick your finger up into where the top latch goes, you'll feel a pressure switch, this tells the car whether the top is latched or not and when its unlatched the car will drop the windows. There are also contacts within the same switch which allows power to go to the top motors. If the top microswitch is broken or has corroded contacts or solder joints, then the top can be intermittant or inoperable.

To get to the top microswitch, remove the two alarm covers (black plastic ovals) from the center windshield cover - they wll just kind of pop out with your fingernail or a very small screwdriver. Then use a Torx bit to take out the two screws. This will allow the center cover to drop down.

There will be three wire bundles - one for the courtesey light, one for the alarm module, and one for the top microswitch. Remove each of them by pressing the clips and pulling. The microswitch is a black module with two silver bars across it and the pressure switch for the latch is underneath.

Just use a pair of needle nose pliers to pull the retaining clips off while rotating them back and forth; be careful and they can be reused for the new microswitch.

I just did this exact repair on my '99 Boxster last week. It only takes about 10 mins.

thstone · 01-07-2011, 06:23 PM

By the way, the top relay is on the relay board which is up above the fuze box on the left side of the drivers footwell. Its WAY up in there so you'll almost have to get on your back and look up under the dash somewhat to see it.

The top relay is the biggest relay of all and is double the size of all of the others. Its three rows up from the bottom and on the right side in slots 14 and 15 (double size). All you can do is to pull it out, clean the connnectors using some fine sandpaper, replace, and see if this helps.

911Senior · 01-07-2011, 06:52 PM

I will dismantle the top latch circuitry first thing tomorrow. If the toplatch micro switch is the culprit, like it appears, where did you get a replacement?
Thanks!

Wayne 962 · Wayne 962's Garage

You can get one right here:

Porsche Boxster Convertible Parts - Page 1

I'm still troubled by the top light illuminated on your dash. If the switch were truly bad, I don't think you would see the lamp lit up there, as the roof would think it's closed. There's another switch in the trunk that might be causing issues as well, I would look at that one too, if the one in the front checks out okay.

I was going to include this particular project in the book, but I ran out of space!

-Wayne

JimHoyland · 01-09-2011, 11:39 AM

Has a test been devised ?

911Senior · 01-09-2011, 02:35 PM

OK, following thstone's instructions I carefully removed the microswitch assembly from the housing (2 small press on clips) and bench tested the switches for continuity with my Fluke meter. Both switches worked, but were sluggish. I sprayed the switches as best I could with electrical contact cleaner and lightly oiled all the moving pivot points. Reconnected the plug in connector and turned on the ignition key. The windows dropped and the top motor now works. I completely reassembled the housing back to the top of the windshield and latched the top. Everything appears fine now, but the top closed position light on the dash is still glowing, yet the top is fully closed and latched.
Question: Can any one tell me what switch or electrical signal operates this light? I believe there is another switch under the clam shell cover and another one mounted to the top mechanism near the hard top de-mister connection (behind drivers left shoulder). Thanks

Wayne 962 · Wayne 962's Garage

Quote:

Originally Posted by 911Senior

Question: Can any one tell me what switch or electrical signal operates this light? I believe there is another switch under the clam shell cover and another one mounted to the top mechanism near the hard top de-mister connection (behind drivers left shoulder). Thanks

I don't believe it's any one particular switch. I would take a look at the one above the motor in the trunk - it may be faulty. If the computer is confused about the switches, it will toss the light on.

-Wayne

911Senior · 01-10-2011, 09:59 AM

Wayne,

To your knowledge, is there a way to clear or reset the computer to make the light go out?

Wayne 962 · Wayne 962's Garage

Quote:

Originally Posted by 911Senior

Wayne,

To your knowledge, is there a way to clear or reset the computer to make the light go out?

Not that I'm aware of, but I haven't really delved into that area of the PST-2. I currently have the passenger seat out on my wife's Boxster (we're drying out the carpets from a roof leak + major rain storm - the one that turned into snow in the NorthEast), and I have to reset the airbag lamp, so while I'm in there, I'll take a closer look.

You could maybe try pulling out the control unit from the car and then replugging it in - tech article on that in our Tech Article section: Pelican Technical Article: Boxster Smart Top Roof Control Installation - 986 Boxster (1997-04) -

-Wayne

911Senior · 01-11-2011, 04:54 AM

Wayne,
I will pull out the top control relay and reinsert it to see if it will cancel the light. Let me know if you see anything in the PST-2.
Thanks for your help.

911Senior · 01-11-2011, 02:04 PM

Wayne,
That did the trick. With the ignition off, I pulled out the top control relay, turned the ignition on and the top indicator light was out. I turned the ignition off, reinserted the top control relay and turned the ignition back on. the the top indicator light came on for 1/2 a second and went out.
Thanks, again!

Wayne 962 · Wayne 962's Garage

Quote:

Originally Posted by 911Senior

Wayne,
That did the trick. With the ignition off, I pulled out the top control relay, turned the ignition on and the top indicator light was out. I turned the ignition off, reinserted the top control relay and turned the ignition back on. the the top indicator light came on for 1/2 a second and went out.
Thanks, again!

Cool! I wasn't sure if that would work, but that's a really good data point to have and to recommend for the future! Thanks for letting us know that worked!

I see sunny days with the top down ahead for you!

-Wayne

jamesmcd03 · 06-22-2016, 08:09 PM

First started:
I put the top down, wouldn't go up, emergency brake like goes on and off fine, tried auto button near the roof latch to reset but nothing (windows go up and down like normal). To protect from the rain I had to manually pull as well as press "up" to close the roof now it won't open. The open/in progress warning light will not go off even though the roof is closed.

Tried checking and taking the the 2x fuses and 2x relay switches in and out to remove corrosion. Still nothing. When I press the open and close button it sounds like something is trying to work behind me for 1 second and the rear body part that opens for the roof to fold into looks like it moves slightly.

Please help with any more ideas or fixes.

Many thanks!

James

Boxster_S · Boxster_S's Garage

Thank you very much thstone, your advice concerning the top microswitch was perfect. I dismantled the latch and re-soldered the connections saving me 232 GBP (plus tax) in the cost of a new switch. The top is now working as it should.

ddodgen · 01-19-2020, 06:25 PM

my micoswitch was junk so I got a used one from Ebay and it fixed all. I have had a great deal of luck finding and trusting Ebay Motors for parts like this one.

xsbank · xsbank's Garage

Judging by what you are finding with the other electrical doodads, I would take the top switch apart and hose it down with Deoxit or brake cleaner. My car is dormant so I can't see what the switch looks like closely but you "might" be able to spray it in place. Don't get brake cleaner on the painted console.