Top Control Module 98 SL500

[allanbrand]

I have read other threads on this issue but I am posting mine.
I stored the vehicle and when the battery was reconnected, the top light switch and rollbar panel light stayed on. The power windows did not function.
My dealer concluded the module was fried. Cost $3500.00. I sent the part to rebuild. Cost 700.00. Dealer reinstalled and said it did not work. Returned to rebuilder. Says dealer wants to sell me his new part. He says the unit is OK but to be safe he said that he is replacing the insides of the module with my shell. Awaiting return on Tuesday. Can these units be rebuilt? Is there anything special to do on reinstallation?
Help!!!!!!!!!

[TheV12pwr]

by...Dire Straits
Feel sorry...

[allanbrand]

I feel sorry also. If ther is an alternative, please let me know.

[TheV12pwr]

would've been posting the thread prior to doing the job.
It is too late now isn't it?
My top controler quit once when the battery was replaced(no power windows,no roll bar),in two days unpluged and pluged the unit and worked fine.
It is hard to believe that yours 'fried' just like that...

[tecqboy]

As an electronics engineer very familiar automotive electronics I am very skeptical that your top controller was "fried" by disconnnecting the battery. I disconnect (and re-connect) the battery in my SL 129 frequently while doing certain routine matainance or working on the stereo. For instance, disconnect the battery when pulling the VDO to replace a burned out lamp. I have never "fried" any of the electonics in my car. So, once again a (shop?) which hasn't got a clue about electronic service proceedures thought they could fix the problem without a through diagnosis. Yes, the top controller system is complicated. But it's loaded with machanical limit switches and other components external to the controller which are far more likely to malfunction or get out of adjustment than the controller itself. There are two fuses in the trunk, one for the left window and one for the right window. The windows can draw as much as 15 amps going in the up direction and the fuses are rated at 15 amps; so they are the first things to check. Either fuse open and the top contoller will not work. There is a fuse for the hydraulic pump which must be checked and there is an outside chance the pump my be low on fluid. There is a "float" switch in the fluid resevoir which will disable the top controller if the fluid runs low. There are limit switches which must close and open in proper order as the top deploys for the controller to "know" what postion the top is in. They are known to fail from lack of excercise. They also get loose and fall out of proper position. Newer chassis cars have codes which can be readout to help pinpoint the problem device. Now, you didn't go into detail about how much your shop checked out the car before deciding the controller was bad. But in my opinion, the electronic controller itself would be the very last suspect in this very mechanical system. Just thought of this possibility too. The top contoller must know that the car is in "park" or nuetral and both doors are closed: but I'm not sure from which circuits it gets that signal. Keep us informed.

[LeaUK]

Listen to tecqboy, his advise is excellent and being an Electronic Design Eng myself I would also agree with his comments 100%.

I see all sorts of this throughout the automotive industry because many mechanics do not understand the complex sensor and electronic systems in modern cars. Dealers are just as bad as you have found!.

Every time someone here posts that their module has 'fried' I don't believe them - sorry. I believe this is the industry failing to diagnose the problem correctly. My view of modules failing (frying) isn't always correct and I've even proved it wrong with my own car (the IR sensors on my SL did actually deteriorate with time to the point where only new IR modules resolved the problem) but it's 95% of the time due to electro-mechanical components failing - not electronic modules. Especially as there are only a couple which actually see high volts, currents - a common failure mode.

But, sorry, your story again proves that simply 'plug and play' with modules very rarely fixes the issue. Of course with others telling you this you probably feel even more disappointed and it probably doesn't really help you.

I hope your dealer (or a reputable dealer/mechanic) can resolve your issues.

Lea

[allanbrand]

This is what the dealer has told me.
He put his test controller in the car and everything worked fine. Therefore the conclussion that mine was no good. If this is so, all the other possibilities, fuses etc., are not the cause. Do I trust the dealer? I know that I will be on site when the controller is reinstalled this second time and I will make him show me, if mine doesn't work still, his functioning test unit.
Assuming the test unit works and my rebuilt doesn't, do I presume my rebuilder is not competent? Tough question when honesty is an issue!!!!

Thanks for your responses.

[TheV12pwr]

What was the dealer 'good' price...let us know pls.

[philbone]

Just for the record..

I was foced to Jump Start my car a while ago and before I could say "don't do that", the person "helping me" went and connected the jumper cables to my battery while his "jumper" car was still running! This has been know to fry the top module due to the 14.5V spike that gets sent down the MBZ line and which it doesn't like. If the "jumped" MBZ car has the ignition turned on at the time, more serious fying damage can be done! Please be careful!!

Anyway, after my car was up and running the same sign; the roll bar switch lights and the top switch lights were constantly on and refused to function.

A quick call to two MBZ mechanics that I know and the same response - time to buy/repair the top module.

After a GREAT deal of research here and elsewhere I took a gamble... I had read many times that it is not advisable to remove power to the car totally, but I had nothing to lose anymore and had to replace the worn out battery anyway, and so I disconnected the battery altogether and left it off all night (gasp!!!!).

Next morning I replaced the battery for a new one, turned the ignition key and, amongst a great deal of flashing and whirring, the entire system came back online! So... I had to re-enter the radio codes and everything was back to normal! I also noticed that the infra-red key sporadic problem that I had before, also disappeared!

I would guess that the whole system benefitted from a "hard reset". Seems to make sense .....

Oh the cost....?

$136.00 (for the new battery!)

Please try this BEFORE you spend $3,800.00 on a top module based on the expert diagnosis.

1997 SL500 AMG Sport

[schabey]

I feel for you guys as I am in the same boat! We disconnected battery and reconnected it after car came out of storage. Various window issues, now they are stuck down, and roll bar light and top light are contantly on. Checked window fuses, okay, and have a clicking sound comind from behing the seat. I went to MB dealer and had codes read. sure enough, according to dealer I need a new module too for $1857. Is it worth checking other issues out or shouodI believe dealer?

[tecqboy]

Do you hear the relays "click" ( under the back seat ) when you push the window switches? If so, the controller is probably OK. The relays interface the controller electronics to the high current window motors. The window fuses are in the trunk; right side top. Often these fuses "look" OK, but are not, especially if they are the original aluminum style fuse. ( They corrode in their sockets ). If your vehicle is 90 thru 95 it does not have window limit switches in the doors. ( motor just stalls ) Later models use a switch to lower the window a tad when you open the doors. These switches can fail or stick. There are many posts in the forum on diagnosing this issue. Do a search. In my experience, the control modules do not fail due to disconnecting / reconnecting the battery for normal storage or maintenance.

[schabey]

The clicking behind the seat is constant when the car is on. According to MB dealer the codes on the car indicated the soft top module and the code could not be reset. Should I take them at their word? Can one rebuild the module or should I buy a rebuilt one?