cowiepeters

A few days ago the roof pump on my car (2003 SL55) continued to run for a while when the roof was fully open and the front windows did not descend. Closing the roof was fine.

Two nights ago the pump continued to run when the roof was closed, the windows did not fully rise the last 1/4" and the red warning screen and chime run when driving.

The roof and trunk lid appear to be closed and locked. The trunk lid cannot be opened with the roof closed with the remote or with the trunk lever

These are the exact signs given in the vario roof diagnostic aid (I found it elsewhere but it is attached in one of the threads) for an open circuit at the S118 tubular frame lock microswitches.

The switches are buried deep on either side of the trunk behind the trunk lining.

Has anyone had any experience with finding out what has gone wrong with them?

Any hints on removing the trunk lining?

The switches are in series and it's likely that just one is not working.

Are they or one of them likely to be "broken" or just requiring an adjustment?

Thanks

Peter
Sydney
Australia

cowiepeters

Further investigation revealed that the switches are difficult but not impossible to remove without removing the trunk (boot) lining from both sides

You need to start to open the roof and pause it with the trunk (boot) open and before the flaps start to move.

This is easy to do with the SmartTop installed as you operate the unlock button on the car keyfob three times to open the roof and press it twice to halt the operation

The photos show the right hand switch in position and various details

Removal: slide a long small flat blade screwdriver down the medial aspect of the support plate you can gently pry apart the bottom lug, leave the screwdriver in position

Slide a second similar screwdriver down and pry apart the top lug leaving the screwdriver in position

With a third screwdriver apply rear-wards pressure to the switch and it will slide out.

One of my previous questions is answered: There is no adjustment possible for this switch.

Gently remove the connector from the switch and secure it so it does not fall into the bowels of the trunk (boot) never to be seen again.

I tested the switch with a multimeter and it connected when the lever was pressed with a typical micro-switch click.

I repeated the removal and testing procedure on the left side... same results.

The switches send an earth message to the computer when actuated so I confirmed the earth connection (on the left switch connector) and confirmed the continuity of the wire leading to the right switch.

I replaced one switch at a time and alternatively shorted the connections to both switches to test whether it was the actuation of the switch that had failed.

No change to the symptoms.

So I am back to the drawing board and thinking that the problem now lies with either the roof controller not sending the message to close one or the other of the tubular frame lock hydraulic cylinders or a failure of one of the cylinders themselves.

Any suggestions?

Thanks

Peter

cowiepeters

At a dead end and about to start replacing things I decided to step back and reconsider. Something didn't make sense.

I decided to buy a Star Diagnosis System

AUD$498 Ordered Sunday arrived Wednesday

Good looking, heavy cables, a nice looking bit of kit.

Helpful vendor (b-art_@live.nl) who arranged a link with my laptop and set it all up (and did it again after I mucked it up)

Ran the DAS and came up with error codes suggesting that the roof latch microswitches (S69) were either faulty or the wires were broken

Same symptoms as the S118

I removed the roof lining and the switches did the usual microswitch click and were operating correctly when the latches closed.

The DAS suggests a way to see if they were working by removing a connector (N52) from its socket beneath the RH luggage box behind the seat but I couldn't identify the connector at all.

The switches and wires are all sealed and part of a single wiring harness that leads all the way through the roof and down into the trunk and then behind the RH seat. Not being able to test the switches I decided to cut the wires on the left side as they ran towards the side of the car.

Using a multimeter I showed that the switches were operating normally which led to the possibility of a broken wire.

I fed the pair of wires through the cable clips and gently pulled on the wires to get a bit of slack in the outer casing and the blue wire pulled out about an inch. Then another few inches with a bit more of a tug.

Tracing the cables back further revealed some chafing around the pivot point for the front section of the roof. I cut the outer covering which revealed no blue wire.

I replaced both wires, soldering at each end, reassembled the vital bits and everything worked perfectly.

Problem solved!

The "proper repair" would involve replacing both microswitches and the wiring harness which would have involved taking half the car to bits on the way back to the connector beg=hind the RH seat.

I reckon that the Star system has probably paid for itself already.

The photos show both latches locked and unlocked (the microswitches can be seen) and the location of the repair in the cables.

Although the roof mechanism appears to be generally reliable and the theory is that using it regularly is good for it this problem appears to be use related and is probably going to happen to someone else.

My vehicle with 110,000 km is used at least 5 days per week and the roof is generally operated twice each day on 4 of those days.

Based on past experience I reckon that if I had taken it to the dealer it would have cost me at least the switch/ harness combo, a days labour and probably a few of the hydraulic cylinders and the main pump.

I hope this helps someone else!

Peter

GET TUBED

Well done mate. You did yourself proud. Thanks for posting.

mightycpa

Peter, you are the man!

Where in the world can I get replacement microswitches? The MB dealer says they are part of the assembly...

I'm repairing all 5 cylinders in mine, but I don't think that's the end of the problem.

Thanks

Rick SL55

great post and work

cowiepeters

You will probably be able to source a microswitch from an electronics supply firm that will fit or you could modify one to suit but I would be reluctant to blame the microswitch.

The're pretty durable and don't usually fail.

You can check if they are working by cutting the pair of wires that lead from the left switch back along the top of the window and test the switches with a multimeter. They are in series so you should get continuity when both switches are actuated (squeeze the lever on the micro switch with your fingers)

The far more likely culprit for this fault is in the wires around the first hinge joint in the roof where they are forced to fold and straighten with every operation of the roof

If you get this fault I would be inclined to cut the wires about 6" forward of the hinge and give each wire a gentle tug. If one comes out it's broken and you will need to splice a new one in.

You could replace both switches and the wiring harness that runs back through the roof and to the board under the storage box beneath the right seat but that's a lot of work and the harness switch set is probably costly.

Having had a little play with the roof mechanism now I would not be inclined to just replace everything that moves... that's a dealer strategy, The Shotgun Approach

Finish the cylinder job then see what happens

Use the VarioRoof Diagnostic aid available on this forum and other places and see what any symptoms match.

Get hold of a STAR Diagnostic set and check for fault codes

Good Luck

Peter

Walter Weakley

Does anybody know the limit switches on Vario roof? open roof and fold into the boot but the boot does not close, everything stops.
switch number and location pls

bobterry99

Walter, post this over in the R172 forum. If nobody helps you there by the end of this week, I will reply with the information you request.

Walter Weakley

No nobody replyed, still waiting for advice. my roof open and fold up in boot but boot lid does not close.

MikeJ65

S69/11 which is located just in front of the right B-pillar is the roof stowed switch.

cjhazard

This post helped a lot. I was having the same exact problems, and I actually performed this repair.

It resolved one of the problems, but for some reason, my car is still not detecting when the roof is fully open and closed. The pump just keeps running. I'm taking it to the shop soon because I can't figure out why the car's micro-switches don't seem to be communicating properly even after replacing those bad wires. If anyone has any suggestions, or things to try, I would greatly appreciate it!

MikeJ65

Do you have any diagnostic tools? It is better to see exactly what the controller sees vs trying to diagnose with a voltmeter. At the end of both open and close cycles, the control is looking for the frame lock switches to be recognized. I would start there. Either they are not closing or you have a switch or wiring issue.

yovenim

It seems that you are experiencing issues with the roof pump and microswitches on your 2003 SL55 car. The pump continues to run when the roof is fully open, the front windows do not descend, and the roof and trunk lid appear to be closed and locked. Additionally, the windows do not fully rise when the roof is closed, and there is a red warning screen and chime while driving.

Based on the symptoms you described, it aligns with the signs given in the vario roof diagnostic aid for an open circuit at the S118 tubular frame lock microswitches. These microswitches are located deep on either side of the trunk behind the trunk lining.

Finding out what exactly has gone wrong with the microswitches can be challenging without a proper inspection. However, it is possible that one or both of the microswitches may be broken or require adjustment.

To remove the trunk lining and access the microswitches, it is recommended to consult the vehicle's manual or seek assistance from a qualified mechanic who is familiar with the specific model of your car. They will have the necessary expertise and tools to safely remove the trunk lining and inspect the microswitches for any issues.

It's worth noting that the microswitches are in series, so if one is not functioning correctly, it can affect the overall operation of the roof system. Proper diagnosis and adjustment or replacement of the faulty microswitch should help resolve the issue you are facing with the roof and windows.

If you are unsure about performing the inspection and repair yourself, it is best to consult a professional mechanic or visit a certified service center for assistance. They will be able to provide a thorough diagnosis and offer the appropriate solutions to resolve the problem with the microswitches and ensure proper functioning of the roof system.