R129, Correct Roof ECU?

[AGod]

Can anyone confirm if I have the correct Roof ECU for my 500 SL 1991? P/N: 129 820 00 97

I purchased the vehicle with a demonstration of the hood & roof working, albeit with a slight hand, as I was told it hadn't been used for a while.

When I collected the vehicle a couple of days later, I noticed that the roof button constantly glowed red and the roll bar switch light stays on, as I drove it home. I should have checked when I collected the car, but I'm no expert.

I have a very good reason to believe that guy swapped the roof ECU over with a faulty on. Therefore I would like to make sure I have the correct roof ECU before I send it off to get refurbished.

Many thanks in advance.

 

[BTB 500]

Can anyone confirm if I have the correct Roof ECU for my 500 SL 1991? P/N: 129 820 00 97

I purchased the vehicle with a demonstration of the hood & roof working, albeit with a slight hand, as I was told it hadn't been used for a while.

When I collected the vehicle a couple of days later, I noticed that the roof button constantly glowed red and the roll bar switch light stays on, as I drove it home. I should have checked when I collected the car, but I'm no expert.

I have a very good reason to believe that guy swapped the roof ECU over with a faulty on. Therefore I would like to make sure I have the correct roof ECU before I send it off to get refurbished.

Many thanks in advance.

Permanently lit roof and rollbar switches can often just mean that the car has some error codes logged ... this can happen due to low battery voltage for example. Not sure what the process for getting them checked/cleared on an early R129 like yours is though - with later cars it's done via a STAR computer.

 

[Doodle]

I believe that number is correct for a car of your age, yes.

 

[AGod]

Permanently lit roof and rollbar switches can often just mean that the car has some error codes logged ... this can happen due to low battery voltage for example. Not sure what the process for getting them checked/cleared on an early R129 like yours is though - with later cars it's done via a STAR computer.

Ok thanks, I'll get someone like BBA or ATP Electronics to test the unit first.

 

[AGod]

I believe that number is correct for a car of your age, yes.

Thanks for confirming DolphiN Tech.

 

[stoneage]

HI,before you send this unit off, have you tried clearing the fault codes, this is done by means off the 16pin socket under the n/s off the hood, i can send you this information, this socket can be used to check all the equement on this modle and cancell any fault codes. PM ME YOUR EMAIL. YOU NEED AND EXTERNALL HARD DRIVE THEN YOU CAN STORE IT FOR FUTURE REFF.[ YOU CAN STORE IT ON COM. IF YOU GOT ROOM

 

[AGod]

Thanks Stoneage. I have an external HD. I'll PM you in a sec..

 

[AGod]

oh, I'm not able to PM you as not up to 30 posts yet : )
Please send info to xxxxxxx
Many thanks!

 

[AGod]

Using a wire with an LED I connected pin 1 & 10…. looking at the roof switch it continued to glow red with no flashes. I repeated this action several time and the roof switch & roll bar light continuously glow red. The LED on the wire did not even light up.
When I connected pi 1 & 7, the LED flashed twice (I’m 99% sure it was 2 flashes. I repeated and it did not flash again. From the list of codes you sent me –2 flashes = Roll bar control unit
Pin 1 & 16 just glows red.
Do you think I should send the roof ECU to get refurbished? I’m being quoted £300.
If i can locate the tool, shall i manually remove the hard top and try reading the codes again?

Also when i viewed the car the passenger window slowed and stopped short (5cm from top) The passenger window now works after a Merc specialist greased it up (although it's a little slow), but now the drivers window does nothing (stays closed) - it was working perfectly fine before. Quite frustrating, but i guess this could be linked to the window?
I would really appreciate anyone's help? Sorry for such a story!

 

[AGod]

Correction = i guess the driver window not working could be linked to the ECU

 

[Alex Crow]

Do check all the torpedo fuses in the boot, even if they look fine the ends can corrode.
If the windows stop working these fuses are the most common cause. Later models use blade fuses and do not suffer this issue.

 

[AGod]

Thanks Alex.
The fuses in the boot weren't looking to good - probably because the plastic cover is missing! Anyway, I've replaced all of them.... and the drivers window is now working!! Very happy!
I did notice that there is a small fuse missing in no. 4 - not sure if there's meant to be one there?

Now I have noticed that the roll bar light on the dash is permanently on. I shall try and re-read the codes and see if that does anything...

 

[neilrr]

I've got a roof relay with the part # 129 820 00 97 if you find you need one.

I'm not too far away from you & am in regularly (this Sunday for e.g.) so you could plug it in & see if it provides a remedy.

 

[AGod]

Hi Neilrr,
That would be great to try a working ECU and see what happens...
Please drop me your details to alexsgodwin at yahoo. co. uk
Cheers

 

[AGod]

So, Neil arrived with a working roof ECU, i disconnected the battery and swapped the ECUs over... reconnected battery, opened both doors and turned the ignition so all dash board lights were on..

The difference this time was that the roof switch & roll bar switch were no longer glowing. So i moved the roof switch and nothing happened. However, you could hear a click every time i moved the roof switch - this came from below the small side roof window behind the driver's seat. I tried to re-set the codes by linking 1 & 10, but nothing changed.

One thing that did happen was the driver's window stopped working - it had blown a fuse again. Replaced that, window working again, but no difference to the roof.

I think it might be time to take it to an Indy.... does anyone know a good one near Epsom / Leatherhead area?

 

[Howard]

Hi there.

Give Colin at Colin Ferns a ring , he's in Richmond but knows his stuff.

He's done a fair bit for me and my dad on our cars.

Mercedes in Richmond - Used Mercedes - Service - Command SatNav Retrofits

Good luck

H

 

[AGod]

Cheers H. Booked in at Richmond for next week..

 

[neilrr]

Any nearer getting to the bottom of this?

 

[AGod]

Colin Ferns have confirmed the roof ECU needs refurbishing for starters...
Won't see the car until after xmas/new year. Will keep you posted..
So for the time being... have a merry Christmas all !!

 

[neilrr]

Alex,

How did they test the roof ECU?