[macysum]

I've been puzzled for a few months about my roll bar. I have the roll bar idiot dash light lit and the roll bar switch blinks when the bar is down. I've had BBA Reman rebuild the soft top controller ($390) behind the passenger's seat but that did nothing to change these symptoms.

It all started when I asked my upholsterer to recover the convertible top lid and recover the roll bar. He took the roll bar off and recovered it with original MB vinyl. Now these items look great but I got roll bar fault issues when he completed the work.

I searched the forums (http://www.benzworld.org/forums/r129-sl-class/1324795-r129-roadster-soft-top-electrical-controller.html) and several of the posts said my symptoms indicate the soft top controller MY '90, PN 129 820 0097, is faulty. I had my upholsterer pay for the rebuild but after reinstallation it still has the same fault. The fuse in the trunk was also blown when I got the car back and the seat belt retractors would not operate properly until I installed a new fuse. That is fine now.

The top goes up and down properly except the roll bar will come up before completing the cycle (either up or down)...the logic knows there's a fault in the automatic roll bar deployment system somewhere and it wants to ensure the vehicle is safe.

Where to check next? Any suggestions?

 

[Pete S]

Macy I am not sure if all R129s are equipped with the Star Diagnostic System but maybe try checking to see if there is some type of code/reset function that is only available through SDS.

 

[TopHydraulics]

Macy,

have you actually read the roll bar codes with an LED code reader?

Did BBA give you an explanation of what they found wrong with the controller, and what exactly they did? If I was to "rebuild" someone's controller, then I would feel responsible for having provided an improvement, being able to explain it, and not charging the full amount if the rebuild was not necessary. Part of the reason why Top Hydraulics does not rebuild controllers is because the rebuild is not necessary for most controllers, and I would feel obliged to help the customers diagnose their problems further. Certainly, BBA should have a way of testing every function of the controller when it comes in, and they should have a log of that initial test which they should be willing to share with you...

Klaus

 

[macysum]

Klaus,

Calling BBA Reman is on my list of things to do as is building a OBD 1 flasher so I can read the codes.

It would be nice if its only the computer needing to be reset.

 

[macysum]

Read the codes

Klaus,

Calling BBA Reman is on my list of things to do as is building a OBD 1 flasher so I can read the codes.

It would be nice if its only the computer needing to be reset.

Read the codes today from my OBD I connector... The DTC readout on Socket 10 gave me a 23 (Roll Bar Control Module) and Socket 7 exhibited a 3, 4, 5 and 6. I cleared 3, 4 and 5 on the Roll Bar Socket but 6, Roll bar deployment solenoid, open circuit to Battery or Ground persists.

I'm calling BBA Reman this afternoon but wanted to see if anyone's seen this code by itself. I've perused the forum and couldn't find much except potentially removing the trunk mounted fuse to reset the solenoid (?)

The Roll Bar dash light stays on and the dashboard switch blinks unless I manually raise the bar.

 

[TopHydraulics]

Congratulations, looks like a successful code reading to me!

Check for wiring problems directly at the roll bar deployment solenoid. The solenoid is near the top of the roll bar cylinder assembly, so it is fairly close to the upholstery that has been worked on. It could be that your upholsterer accidentally cut or damaged a wire going to that solenoid, or disconnected it, and this could be a really easy fix.

After all, the code implies that the solenoid circuit has a problem with conducting current. That explains also why the warning light is not on when the roll bar is up - the deployment solenoid's function is not essential when the roll bar is already up.

Klaus

Top Hydraulics | Rebuilt and Upgraded Convertible Top Cylinders, Pumps, Hydraulic Lines - Top Hydraulics, Inc

 

[macysum]

Didn't see anything obvious from looking at the solenoid wiring. Strange that the solenoid was not where the diagrams say it should be ...it was almost on the floor, not up near the roll bar cylinder assembly.

Next I'll check continuity of the wiring to the RST Controller but can someone send the pin-outs? I'm not at my computer that has the Star DVD.

 

[TopHydraulics]

The picture in your post appears to be the roll bar valve, which is used for manual roll bar actuation. Why is one solenoid on it disconnected?

 

[macysum]

Klaus,
I had disconnected the cable from the socket to check the integrity of the wires in that picture.

You must be right as there's a cable connecting to the top of the roll bar cylinder.

The pdf Poundy attached in http://www.benzworld.org/forums/5409956-post10.html isn't quite correct for my 1990 R129...I have the larger control module (N52) built by Becker, not the smaller (N53) item with the Bosch logo on the top. That's what threw me with Y57/1...the later model (post 6/95 show the solenoid Y57/1 as the same one in the first picture).

I'm suspecting that the cable connecting into the solenoid on the roll bar (Y57/1 - center of photo attached) could be problematic from first inspection.

 

[macysum]

All Cleared

Success - the dashboard and roll bar switch lights are both cleared off.

Sure enough both wires to the solenoid had a couple of whiskers shorting across to the other wire. My guess is the upholsterer unhooked the connector by pulling the wires and not using a flat screwdriver and coaxing it away from the socket. That frayed the red and brown/white wires just enough to short the circuit...

Solution was to tin both red and brown/white wires, put some heat shrink on them up to the pins and reinstall into the male connector.

Thanks for the support Klaus! As usual you have the deepest knowledge of the Roll Bar/Top Hydraulic systems outside of Stuttgart.

Obviously BBA Reman rebuilt a good Soft Top Controller
It would seem they should have tested the unit when they received it and if it tested out fine, return it "No Trouble Found."

Here's a close up of the frayed wires for the forum in case someone encounters a similar roll bar code 6 in the future.

 

[lowesguy]

Good job finding it!

 

[rorypff]

Congratulations on solving the problem - very good technical descriptions. You must be very happy:wink

Of course to Klaus it goes without saying:smile

 

[TopHydraulics]

Macy,

I'm glad that you were able to find the wiring problem. Code reading and tracking down the fault via the code description did the job!

Controllers get blamed all too often. You mentioned in the first post that you had initially studied several threads in http://www.benzworld.org/forums/r129-sl-class/1324795-r129-roadster-soft-top-electrical-controller.html and come to the conclusion the controller was bad. If you recall which thread or threads originally lead you to that conclusion, could you post a reply to it (them), describing what you went through and reference this thread for more details? That could help future readers with similar trouble...

Thank you in advance,

Klaus

www.tophydraulicsinc.com

 

[LWB250]

I'm especially interested in this thread, as my car exhibits exactly the same symptom. However, it's a 1997 model, so the controller and even the wiring is probably different.

I have a DAS system and have been able to read codes from the controller, but not clear them. Whenever I have tried I end up with a "communications failure" error.

I get the following errors when I read the controller:

128, 135 and 136

Here's what's really weird:

The sequence of operation is spot-on. That is, everything works as it is expected to and described in the MB shop manual.

BUT - the roll bar light in the cluster is always lit, and if the roll bar is lowered, the red lights in the roll bar rocker switch flash constantly.

I may send the controller to BBA for a bench test, as I don't want to give them carte blanche to "rebuild" a good controller.

Suggestions?

Dan

 

[LWB250]

For what it's worth I checked the roll bar release solenoid today.

While the wiring seems like it was stretched and run around some pretty sharp corners, it is the original harness and tested out with a continuity tester while being moved, stretched and wiggled.

I pulled both ends of it and checked the connectors and both were in good condition with no errant conductors sticking out anywhere.

I also checked the solenoid itself by applying 12VDC to it, and it worked as expected.

I guess this puts me back at the beginning, with a need to send the controller in for testing....

Dan

 

[macysum]

I'm especially interested in this thread, as my car exhibits exactly the same symptom. However, it's a 1997 model, so the controller and even the wiring is probably different.

I have a DAS system and have been able to read codes from the controller, but not clear them. Whenever I have tried I end up with a "communications failure" error.

I get the following errors when I read the controller:

128, 135 and 136

Here's what's really weird:

The sequence of operation is spot-on. That is, everything works as it is expected to and described in the MB shop manual.

BUT - the roll bar light in the cluster is always lit, and if the roll bar is lowered, the red lights in the roll bar rocker switch flash constantly.

I may send the controller to BBA for a bench test, as I don't want to give them carte blanche to "rebuild" a good controller.

Suggestions?

Dan

Dan,
I don't have the code description for '97 and above...what are the meanings for the readings 128, 135 and 136?

Took me some time and trial and error to sort mine. I'd certainly ask BBA Reman to bench test before spending any rebuild $$.

 

[MBRyan]

Macy,

I'm glad that you were able to find the wiring problem. Code reading and tracking down the fault via the code description did the job!

Controllers get blamed all too often. You mentioned in the first post that you had initially studied several threads in http://www.benzworld.org/forums/r129-sl-class/1324795-r129-roadster-soft-top-electrical-controller.html and come to the conclusion the controller was bad. If you recall which thread or threads originally lead you to that conclusion, could you post a reply to it (them), describing what you went through and reference this thread for more details? That could help future readers with similar trouble...

Thank you in advance,

Klaus

www.tophydraulicsinc.com

Dear Klaus,

I have several error codes on roll bar module, one of them is error 6 - Roll bar deployment solenoid, open circuit or short circuit to Battery + or ground (-).

Checked wire from roll bar module to roll bar deployment solenoid, no short there. How can I check Roll bar deployment solenoid? I measured resistance on solenoid and got only 0,8 ohm. Is that ok, seams very low.

 

[bobterry99]

The steps for troubleshooting roll bar fault code 6 are here: http://manual.startekinfo.com/manual/JSP/ba6/19_2/m23.jsp#6.0.

 

[MBRyan]

Thank you! These is really good, will try to do these steps.

 

[MBRyan]

Hello all,

I'm restoring R129 which I bought recently. I'm trying to troubleshoot roll bar. Roll bar is in up position and I can't get it down. Roll bar is not lowering when RB switch is pushed and I can't hear any of relays clicking in RST module. Tried to hold RB switch up for 10 seconds and then lowering RB, but nothing.

I had many error codes in RB module 3, 5, 6, 7, 8. I erased RB module errors, could clear all but 4, 5 and 8. 4 and 5 I guess are ok, because both seats has been taken out and all wires disconnected, but for error 8 I'm not sure. Should I be able to lower and rise roll bar if both seats are out and disconnected and roll bar module has errors 4,5, and 8?