[Zaxxon]

Soft top not opening - Code 064 "Road Speed Status Signal"

Hello!

Now that I got almost all the issues of the car taken care of, I am trying to get the soft top operation a bit more reliable. The mechanics are in great shape, all is well there, but I do have this annoying code in the top controller pretty regularly.

I erase codes at night, drive the car to work in the morning (about 15mi), and after that drive the code may or may not be set again. It's 99% of the time set again at the end of my drive back home however. I also do get an occasional ABS/ASR fault and non-functioning cruise control.

I understand that this code is basically there because the soft top controller isn't getting the proper speed signal, and therefore doesn't allow operation. I am thinking I have a problem with a wheel speed sensor, and I am thinking it is the left front sensor that's responsible for all these things. I guess it could have something to do with the gauge panel, but all seems good there from what I could tell, and I am pretty sure my speed dependent volume control of the radio is working. I checked the wiring of the LF sensor and cleaned all connectors, but that didn't make a difference. I suspect a sporadic, time limited fault, since the sensor is not exhibiting any problems just putting a scope to it and turning the wheel.

My question basically is if I am overlooking anything, and if it really is the LF sensor that's responsible for this on a '96, since I've read many posts about this, and there seems to be some evidence that at least for some years the MB docs are wrong, and it's NOT that sensor, but a transmission mounted output sensor or so? This car is a '96 model, but with a late '95 production date.

Thanks for all your help already in advance - it's much appreciated!!!
--Zax

P.S: Please ignore the window sync code - it was still in there from me pulling the controller fuse and not syncing the windows since. Usually the 064 shows up by itself, occasionally together with a code for the brake light switch, which is already on order.

 

[Zaxxon]

One more piece to the puzzle - set the A/C controls into diagnostic mode and checked the speed in the little LCD display. Seems to have accurate speed ratings (km/h) throughout the whole drive. Only thing that seemed a bit off is that it takes a bit to go from 0 to an indicated speed when just taking off, but I guess that's a general delay in that readout.

Odd was also that I cleared the code last night and the top was operating just fine, then moved the car into the driveway and this morning it seems to have the code again, as the top once more won't operate (blinking top control switch when attempting to open). So either the code set right away again driving the car that short distance, or on restart this morning.

I am really puzzled by all this...

 

[bobterry99]

My question basically is if I am overlooking anything, and if it really is the LF sensor that's responsible for this on a '96...

I have the notion that the speed signal on your car is a synthesis of signals from two sensors, since in a curve the outside wheels turn faster than the inside wheels.

The speed signal received by the roof controller originates with the ASR module. If the problem is caused by a wheel speed sensor, then I would expect to find a code in that module identifying the sensor. Otherwise the problem may be the signal from the module, and since this problem is intermittent making that determination could be challenging.

 

[Zaxxon]

I have the notion that the speed signal on your car is a synthesis of signals from two sensors, since in a curve the outside wheels turn faster than the inside wheels.

The speed signal received by the roof controller originates with the ASR module. If the problem is caused by a wheel speed sensor, then I would expect to find a code in that module identifying the sensor. Otherwise the problem may be the signal from the module, and since this problem is intermittent making that determination could be challenging.

Thank you so much for your response - I am not terrible in electrical diagnostics, but certainly not at your level, and this has been driving me crazy!

Yes, I have a feeling it will by quite challenging...the only code I had in the ASR module was the one for the brake light switch - I will be replacing this today, however, it seems that code is much more sporadic in frequency than the VSS one in the top module.

I am pouring over diagrams, and it seems the top controller actually receives a speed signal from the ASR module (Pin 27) - (the same signal from the connection that also feeds e.g. the speed dependent volume control of the stereo as well as the A/C controller, and it also receives a VSS Status Signal, which goes in a harness that has apparently pretty inaccessible connectors from the ASR module (Pin 5) to the top controller (Pin 10). Looks to me that I am dealing with an incorrect output of that one. The description of the diagnostics of that signal is a bit hard to read, I attached it to this post.

The way I am reading this is that in a fault case, there are more than 3V AC on top of more than 10V DC on that pin? If that's the case, what is there in a no-fault situation? Nothing? Could I just disconnect this wire and see if the top is working fine then as long as the car isn't moving, since the other VSS signal might be working, just as a test? Or does it mean no fault = more than 3V AC, fault = less than 10V DC?


Thanks again,
-Zax

 

[bobterry99]

The way I am reading this is that in a fault case, there are more than 3V AC on top of more than 10V DC on that pin? If that's the case, what is there in a no-fault situation?

That M-B description of the signal is nonsensical to me, and it seems to contradict the description given by the diagnostic manual for the top controller. I don't know what to believe. You could determine yourself through experimentation, since your system is normally fault-free and it is easy to create a fault by disconnecting a wheel speed sensor.

Could I just disconnect this wire and see if the top is working fine then as long as the car isn't moving, since the other VSS signal might be working, just as a test?

I believe the purpose of having two signals is to check the plausibility of the speed information, so if you disconnect a wire that will invalidate the signal from the connected wire and generate a fault.

As a last resort you could construct a simple circuit to mimic the two speed signals and fake-out the controller. Inherently, this circuit would add the feature of allowing the roof to operate while the vehicle is in motion up to a speed of your choosing.

 

[Zaxxon]

That M-B description of the signal is nonsensical to me, and it seems to contradict the description given by the diagnostic manual for the top controller.

Yes, it definitely contradicts that, BUT, it somehow makes a lot more sense to be honest. The only other place where this VSS Status is used, would be the ADS module, which my car doesn't have. I guess I could hook up the scope and go for a ride and see what it does...

I believe the purpose of having two signals is to check the plausibility of the speed information, so if you disconnect a wire that will invalidate the signal from the connected wire and generate a fault.

If the info above is actually correct, this would make total sense, especially considering how catastrophic an accidental top opening at 180km/h or so would be

As a last resort you could construct a simple circuit to mimic the two speed signals and fake-out the controller. Inherently, this circuit would add the feature of allowing the roof to operate while the vehicle is in motion up to a speed of your choosing.

Funny you say that...I was actually thinking I could just use a 555 timer or so and build something that simulates what I need. But I much rather get things fixed right.

I am also in the process of selecting a soft top convenience module to install, and they probably do much of the same to "fool" the soft top controller...


Thanks for the additional info - much appreciated! I guess first thing is to replace the brake light switch tonight, and if I get to it, hook up the scope and see what's going on. I'll update once I know more...

--Zax

 

[Zaxxon]

Replaced the brake light switch today and pulled both front wheel speed sensors and thoroughly cleaned them as well as the rings. The sensors had a good size "bush" of metal shavings attached to them on either side, and I would think it could lead to some issues. I haven't driven the car much yet, so we'll see if it fixed anything.

 

[Zaxxon]

So far, so good!

No dash lights since, no codes since. I am knocking on wood as I type, since it just seems too easy of a fix...

--Zax

 

[Zaxxon]

Just a quick update on this and to hopefully close the thread (and still knocking on wood): Up until my possible conductor plate issues this past weekend, the problem hasn't resurfaced again. It seems that the brake light switch replacement and cleaning the speed sensors did the trick! I am still somewhat surprised about the amount of tiny metal shavings that were stuck to the sensors though. There was a good amount of metal on each of them, more so than I've seen before.

I wonder if someone did any sanding close to them at some point, especially since the car came with awfully painted calipers to me...

Thanks again for everyone's help with this!
--Zax

 

[Zaxxon]

Thought too soon it's fixed - it reared it's ugly head again - the 064 code came back and stopped the top from functioning again. This is making me crazy. So, maybe an intermittent speed sensor? Weirdly enough, no ABS/ASR light ever since back then, and also no ABS/ASR codes, just the 064.

It would be nice to have some solid info which speed sensor really is responsible, or if it's a combination of a couple? Somehow I was thinking that teh ABS/ASR code would set right away at a malfunction though, and the logic for the convertible top would be a bit more fuzzy, looking at the safety implications.

Anyone have any ideas?

--Zax

 

[bobterry99]

It would be nice to have some solid info which speed sensor really is responsible, or if it's a combination of a couple?

In regard to that I have nothing to add beyond what I offered in my prior post.

I would purchase or build a device that bypasses the speed signal to the roof controller. That would solve your Code 064 problem and enhance your vehicle. If it is your own design and is microcontroller-based, with a bit of additional effort you could add the ability to fully open or close the top with a momentary touch of the control switch or the car's remote. My R230 has a commercially-available SmartTOP module that has all those features, and I plan to add them to an R129.

 

[Zaxxon]

Hello again!

Thanks for chiming in again, and you know, your original suggestion actually has put me that way - I already have the full solution by Reinhold Engineering in Germany, waiting to be delivered when My parents come over next month, I just wasn't sure if that will take care of the code or if it will just somehow delay/time stretch the original signal in some way, since I know it's programmable for a certain speed, so must be doing something with the original speed signal.
Meaning, I hope it's not allowing the code to be set anymore...until then, I am probably dealing with just resetting it when it happens.

Thanks again,
Zax

 

[bobterry99]

...I just wasn't sure if that will take care of the code or...

I suppose the way these work is the vehicle speed and the roof control switch up/down signals are re-routed from the roof controller to the Reinhold "Comfort" module. The roof controller gets no speed signal at all, and its roof up/down control signals now come from the Comfort module. When you operate the roof control switch based upon speed calculation the Comfort module determines whether or not to issue a control signal.

I suppose the Comfort module will solve your problem. It may not detect the glitch in the speed signals that cause the roof controller to set code 064; and if it does, it would probably momentarily affect top operation only for the duration of the glitch.

 

[Zaxxon]

I suppose the Comfort module will solve your problem. It may not detect the glitch in the speed signals that cause the roof controller to set code 064; and if it does, it would probably momentarily affect top operation only for the duration of the glitch.

Well, considering that it really is a very sporadic fault and doesn't cause any safety/drive-ability issues, I am keeping my fingers crossed that it will! Thanks once again for your help! I'll report back once I installed it next month.

--Zax