R129 hard/soft top release snag

[Talonneur]

I'm fervently hoping that someone out there will be able to shed some light on this very elusive and frustrating fault with my 1991 R129 SL300 -24.

Having read and acted upon the very useful posts already available on here on this very subject, the fault still refuses to show itself.

The first thing to say is that the rocker switch that operates the roll over bar flashes a red light constantly. The roll bar will operate on the switch up to a point where the presence of the hard top restricts it.

Operating the roof release switch makes it (the roof switch) flash, the release mechanism at the rear of the top is audible as it functions, but it fails to release at the front. Notably neither of the front windows lower as they should when the roof switch is operated.

The car is now in the care of a local independant MB specialist who have had the car for many weeks. They tell me that they are now at a complete loss as to where the snag is. They have replaced the battery as the one on the car was weak - no change. They have also tried the synchronisation operations as detailed on this forum - again - no change. The hydraulic/electrical solonoid that is located at the foot of the offside 'B' post was suspected - subsequently replaced - no joy. Various ECU from another 129 of similar vintage have been tried on the car - more frustration - changes nothing!!

They have advised that they suspect an electrical gremlin somewhere and have engaged a local car electrical specialist (who have an excellent reputation) to try and locate the snag. So far - nothing.

If anyone out there can throw any ideas into the mix I would be most grateful - it's a great car and I look forward to many adventures and lots of fun with it - but this infuriating problem is thwarting every effort. I will of course reply to any suggestions or advice and look forward with great eagerness to reporting that the problem has been traced at some point - hopefully soon.

Kind regards

Talonneur

 

[television]

Your flashing roof knob is flashing out the fault code.

Malcolm

 

[stats007]

The hard-top shouldn't restrict the movement of the roll-bar - at it's maximum deflection it doesn't come in contact.

The first thing you need to make sure of is that all the fault codes have been cleared completely - on the early cars this sometimes needs doing twice. You can then see if the system works - if not you'll be able to read a valid fault code. This can be done by yourself - albeit slowly by triggering the codes to flash through the roofswitch light - this isn't done automatically.

 

[Talonneur]

R129 roof release snag

Thank you to Malcolm and Stats007 for your respective replies. Guys, please forgive my uninitiated mind - but could you please be specific and lay out in step by step detail exactly what you mean. I am technically minded and have reasonable ability and repair experience - but I'm completely unfamiliar with MB fault codes and what form they take. So if you are able to provide further guidance I would be most appreciative.

Stats, I note your point about the roll bar - unfamiliarity on my part - I haven't had the beast long!

I haven't personally laid eyes on the car for some time as it has been ensconsed in a local independant MB specialist. They tell me that they have cleared all the fault codes off the various ECUs that these applied to. I'm sure they told me that the car is now not showing any fault codes (I will check though) but the problem remains.

I haven't ascertained whether the roof switch still flashes when it is operated - as presumably this will be significant. In publicising this problem I was hoping that guys like you would be able to pinpoint something hitherto overlooked.

In an earlier conversation with the specialist, I mentioned the technical posts on this forum and the suggestions made. I was assured that they were aware of the forum and indeed contributed to it. Nonetheless, I printed the posts relating to 129 roof snags including the synchronisation procedure and faxed them over.

Thank you in anticipation

Talonneur

 

[Talonneur]

R129 roof release snag

Thank you to Malcolm and Stats007 for your respective replies. Guys, please forgive my uninitiated mind - but could you please be specific and lay out in step by step detail exactly what you mean. I am technically minded and have reasonable ability and repair experience - but I'm completely unfamiliar with MB fault codes and what form they take. So if you are able to provide further guidance I would be most appreciative.

Stats, I note your point about the roll bar - unfamiliarity on my part - I haven't had the beast long!

I haven't personally laid eyes on the car for some time as it has been ensconsed in a local independant MB specialist. They tell me that they have cleared all the fault codes off the various ECUs that these applied to. I'm sure they told me that the car is now not showing any fault codes (I will check though) but the problem remains.

I haven't ascertained whether the roof switch still flashes when it is operated - as presumably this will be significant. In publicising this problem I was hoping that guys like you would be able to pinpoint something hitherto overlooked.

In an earlier conversation with the specialist, I mentioned the technical posts on this forum and the suggestions made. I was assured that they were aware of the forum and indeed contributed to it. Nonetheless, I printed the posts relating to 129 roof snags including the synchronisation procedure and faxed them over.

Thank you in anticipation

Talonneur

 

[television]

You must get the fault codes read out.

The widows do need to be set,otherwise the the roof will not go down as it needs to know where the windows are,this also applies to the Rollbar.

The hydraulic cylinder do go faulty (easy to replace O ring).

What happens if you put the roof down manualy and you try and power it up to close.

malcolm

 

[stats007]

There are a lot of things to try - can I ask you have a read of this and the many other related threads - the code reading is relatively straightforward - if you're not getting any fault codes and the light is flashing permanently then it sounds like the ECU may be at fault.

 

[Talonneur]

R129 roof release snag - update - sorted - but roll bar light is lit!!

Thank you once again to those who posted ideas and suggestions on this problem.

I'm happy in part to report that the roof release snag is now resolved. The independant local MB specialist that had had the car for some time eventually suggested that it needed to go to a dealer who would have greater technical resources available to them.

I did some research to ascertain which dealer in this part of the world (Somerset) had a time served technician with enough experience and expertise, ideally someone was around when the R129 first came out. So it was that the car went to MB in Dorchester where a chap called Roger knew the 129 well and had 28 years service with MB. I spoke with Roger at length prior to delivering the car.

Within a couple of days he diagnosed that the main roof ECU located beneath the rear seat was at fault - at last something positive! Gloom though with the news that the ****** bit alone costs almost £950!

Subsequently I spoke with Roger again, who confirmed that with the new ECU installed the roof now worked perfectly. However - he confirmed that the roll bar rocker switch was still showing a red light and the warning light in the instrument cluster was still on! Having had my pocket emptied already - I asked him not to investigate further.

So - guys - can anyone offer any insight into what or why these lights are on - and how to go about persuading them to go out. Any suggestions/pointers - very gratefully received. My thanks in anticipation...

 

[television]

Is the roll bar working

 

[Talonneur]

Malcolm,

Thanks for responding - yes the roll bar works on the rocker switch. Whether it would work in response to the rear wheels coming clear of the ground as it should - I know not. Any ideas?

 

[television]

Malcolm,

Thanks for responding - yes the roll bar works on the rocker switch. Whether it would work in response to the rear wheels coming clear of the ground as it should - I know not. Any ideas?

Have you tried lowering the roll bar,raising and holding the switch for 20 sec in key 11

 

[Talonneur]

I haven't - but certainly will, not sure what you mean by key 11 - please would you expand on that?

 

[television]

I haven't - but certainly will, not sure what you mean by key 11 - please would you expand on that?

With the key turned to position 11 is ignition on, holding the button when up is the standard reset