1995 W124 Cabriolet - top problems

[NDP 2.6 190E]

Appreciate any advice on the following problems:

Tried to lower the top yesterday and ran into an issue; the rear window part of the top unlatched but did not want to lift away from the tonneau cover. So, while my wife operated the top (down) button, I gently lifted the rear window part of the top which caused the remainder of the top down operation to complete OK.

Next I tried to raise the top. Nothing, no sound from the hydraulic pump motor. The top switch light is now on all the time and a chime sounds when any attempt is made to drive the car.

Built a code reader and initially noted 9 CST codes (2, 4, 5, 7, 8, 9, 10, 13 and 15). Managed to clear them all. But, when I try raising the top I get a code 4 (Limit switch signals illogical). I can clear the code 4 but it reappears if I try to raise the top. Fuses all test OK. No hydraulic leaks.

Also, both seat belt presenters have stopped working. Which seems to be more than a coinicidence.

Have read Kestas threads (very informative) but have run out of ideas on what to try next.

[pawoSD]

It seems like you answered your own question with the code reader. Limit switch illogical means the limit switch is malfunctioning, so the top will not operate. Likely a safety feature of the system.

[NDP 2.6 190E]

Originally Posted by pawoSD

It seems like you answered your own question with the code reader. Limit switch illogical means the limit switch is malfunctioning, so the top will not operate.

Sounds about right. Do you know where this limit switch is and if it can be accessed while the top is down?

Thanks.

[TheDon]

I'd investigate and see if a limit switch has failed.

[RBYCC]

Have you checked the fluid level in the hydraulic reservoir?

[TheDon]

Originally Posted by RBYCC

Have you checked the fluid level in the hydraulic reservoir?

Where the heck is the thing, this isnt even an issue for me and I cannot find it in my cabrio to help this poster out lol

[RBYCC]

Originally Posted by TheDon

Where the heck is the thing, this isnt even an issue for me and I cannot find it in my cabrio to help this poster out lol

It's located behind the right hand side trim panel in the trunk.
First remove the trim panel facing the rear seat back, then the right will pop out.
There is a metal plate that has to be remove that covers the pump and reservoir.
If the fluid level is below the min mark the roof will have erratic operation, some which will show up as electrical fault codes as the limit switches aren't properly tripping.
The FEBI fluid is under $8.00 per liter.

[NDP 2.6 190E]

Yes. The hyd pump is straight forward to get to, the fluid level can be easily checked after the RHS trunk trim panel is removed.

I forgot to mention in my initial post yesterday, the rear 'head rest/roll bars' no longer operate either. They are in the down position. The switch on the dash flashes but provides no movement. Any one know the where abouts of the limit switch(es)?

[NDP 2.6 190E]

Originally Posted by RBYCC

Have you checked the fluid level in the hydraulic reservoir?

Yep. The level is between min and max.

[Kestas]

Check the roll bar fuse. I once had it blow just before the rollbar was completely retracted.
http://www.peachparts.com/shopforum/showthread.php?t=196318

[NDP 2.6 190E]

Originally Posted by Kestas

Check the roll bar fuse. I once had it blow just before the rollbar was completely retracted.

That fuse is OK. I removed, tested and replaced it to be sure.

While re-checking the main fuse box I decided to remove the rear cover - held by 4 screws. The 2nd pic is with the cover removed.


Underneath are some more relays and modules. The blue and green relays near the top left of the picture have fuses. The (15A) fuse on the blue relay had blown! Alas, replacing it made no difference.

The (30A) fuse on the green relay was OK. But, I dropped the fuse somewhere inside the firewall - so will need to replace it anyway.

Am running out of ideas on where to look next. Would like to try swapping out the CST module under the rear seat for a known good one before dismantling the rear of the car to get to the limit switches.

Can anyone recommend a good indy in Orange County, CA?

[vexed]

Sorry to hear no joy. The limit switch for the tonneau cover can be accessed without any disassembly. If you have the wrench to unlock the cover from behind the rear seat, raise the top manually. You then need to raise the bow (rear) of the top and then lift the cover. You'll see the limit switch on the driver's side, the lining for the soft top compartment is held in by plastic rivets.

The other limit switches can be inspected once you remove the side interior panels, not hard or time consuming. Once the seat bottom and back are out the panels just screw in and one hex screw at the rear. That would allow you to inspect the connections. If you lost both seat belt presenters something may have come apart. From what I could see the presenters have separate relays. You may want to do that before swapping out the controller.

The fact that your CST switch is always lit is another issue, usually that means it is available to operate the top but not here.

Something is telling the controller that all systems are not "go" it must think the roll bar is not fully retracted or the windows are not down. Is the roll bar inop using the dash switch? If you can raise and lower it I would cycle it a couple of times.

If you manually raise the top is it also not responding to the switch if you try and close it? From what you posted before about tricking it into finishing the lowering cycle your CST controller is doing something.

[NDP 2.6 190E]

Appreciate the explanation. I'll check to see if I have the top wrench - then try unlocking the cover as you suggest.

[NDP 2.6 190E]

Well, the advice to manually raise the top worked out great. Thanks

My top problem was caused by this tiny screw:


It lives inside the tonneau cover and holds the tonneau latch limit switch (a micro switch) in place. The screw is in the middle of this picture:


Zoom out to show the underside of the tonneau cover. The latch assy is in the middle of this picture:


The latch assembly is normally hidden behind a metal plate held on by 11 x M10 bolts

While testing the switch it quickly became apparent that the screw was loose - allowing it to move about. Took a couple of attempts to get the switch position just right, but the screw is now secured with a dab of blue loctite and the top works great.

Now, I just need to get the seat belt presenters working once more....

Thanks again