300SL convertible top alarm
 

On my 300 SL the convertible top alarm goes off with an annoying frequency. The top is not actually loose. I have recently (about 6 months apart) replaced both of the hydrolic cylinders in the top because they were leaking fluid. It seems that a tilt (or rocking motion) in the car from side to side sets it off instead of a straight on bump. I took it to my local certified mercedes shop, but he has had no luck in finding the problem. I live in a small town and he has not had the opportunity to work on many SL's. He connected it to the diagnostic computer and no codes show, but he has an aftermarket program. He suggested I take it to a mercedes dealership, but it is a terrible inconvience since it is nearly 2 hours away. Please help! Any suggestions would be appreciated. Thanks a bunch!

You might consider checking for fault codes, as explained here:

http://www.peachparts.com/shopforum/tech-help/38215-questions-techs-my-sl-please-read.html

and perorming diagnostics, if necessary, as explained here:

http://www.peachparts.com/shopforum/mercedes-benz-sl-discussion-forum/44939-500sl-soft-top-roll-bar.html[URL]

Sorry, I guess I need to add a few more details. My OVP relay has also been replaced because I was having the exact same problem with the ABS light as the other member. Also, the limit switch in one door was replaced about two years ago. My mechanic read the codes and everything has been corrected that the codes suggested. Then he cleared the codes and drove the car for a while. The problem still exists. He then reread the codes but no codes appear. He (we) are at a lost for what to do. Still it would be hard for me to take the car 2 hours away to a dealership, but maybe I have no choice. This things drives me nuts. It alarms (and flashes) about 12 to 15 times in my 30 minute trip to work! It is much worse on rough roads (I live in rural area) than on the smoother roads in town. Much more sensitive to a dip that causes a side to side motion than to a head on bump. HOWEVER, THANKS EVER SO MUCH FOR THE REPLY. Any further suggestions out there?

What is probably happening is when you hit a bump the soft top controller is getting a false input signal from one of the switches that monitor the position of each latch. Possible causes include the switch having a loose electrical connection or an improper adjustment.

How long does the alarm sound when it comes on? If you immediately pulled-off to the side of the road, would it stop or continue?

Thanks for answering Bobby!
If I stop (and dont put it in park) the sound stops but the light stays lit (not blinking). When I start moving again, the alarm sounds and the light blinks again. The alarm sounds until I depress and hold the button again and let it process through like the top had been off.

One more thing :

Would it be possible that this trouble could have anything to do with my roll bar being deployed once? I mean, does anything have to be reset when that happens? I guess that sounds like a dumb question but I am trying to cover all the basis.

This could be really simple. When you have the car in a state where you are parked and the lamp in the red switch is on, use the special tool to work each of the four latches that are securing the top. The light should go out when you work the latch that has the switch with the problem.

I don't think your roll bar having deployed has anything at all to do with your current problem.

Thanks again Bobby!

I have been so busy at work that I have not had time to check out anything further. I am wondering if I dont need to clarify (once again ), seems I am not good at this posting thing. LOL! The ringing and flashing of the light happens only when the top is ON the car. If the top is off OR the soft top is down, then I enjoy a wonderful peaceful ride with no bells or flashes. It is much worse with the hardtop than with the soft top. So this is what I dont understand.....can you move the latches with the special tool when the top is on the car (doesnt seem logical to me that you could)? I talked to my mechanic and I am going to copy everything here and take it to him. Like I said he is a personal friend as well as certified mercedes mech. He just hasnt seen many 300sl because it is a very rural area. Also, I have some of the earlier posts where you have helped others for him to read. He is very open about the idea of getting help here. Thanks soooooo much for your time and efforts!!

There should be a tool in the toolkit that manually operates the front and rear latches. The front latches are operated through those small covered holes in the header panel (behind the sunvisors).
The rear ones operate through slots in the front trim panel in the trunk. It should show where most of this is in the owners manual.
The mechanic should be capable of retreiving fault code and actual values through the control module diagnostic port, if not, you need to find a shop which has this equipment.
If all the latches are found to be fully locked, then the diagnostic port may be the only efficient way to find out which switch is defective, unless you mechanic wants to go through each switch individually and test them. He could do this easiest at the connector at the control module which handles all the input signals. There may even be a stored trouble code (DTC) which will immediately indicate what switch or latch is defective.

Gilly

You use the special tool that Gilly describes with the top on the car. In fact, the front latches are designed to close only if one of the tops is in place. The purpose of the tool is to allow the hard and soft tops to be operated if the elctro-hydraulic system is not functional.

If you can get a stored DTC for the problem as mentioned by Satern and Gilly that would be great. I think the only way for you to capture one is as follows. When the problem occurs, stop the car and push the top button forward to latch the top. If the lamp in the switch goes out, the top is fine and you have no code. But if you hold the button and the lamp stays on, after a moment the lamp will flash. If that happens, a fresh DTC has been stored for the problem. You can follow Satern's post and use a wire to retrieve the code and report it here for us to look-up.

If you can't get a code, I think you'll have to play with the latches as I suggested in an earlier post. You may find it necessary to go to the electrical connector like Gilly mentioned and check the switches that monitor the state of each latch. That is a bit time consuming, but it is easy. If you find yourself going that route, I can guide you with a simple procedure.