Timroperco

Hmmm ... this is a puzzler. I just went out to my Cab to see if I could duplicate your problem.

I unlatched just one of the top latches -- the passenger side -- then put the car in gear. The red switch light, which had been solid, started blinking ... and the chime commenced, then stopped. It began chiming again whenever I released the brake and let the car roll. I unlatched the other top latch, pulled back on the red switch and all worked fine.

So it seems your car is sensing a problem, it thinks the top is not fully latched down, or similar. The could indeed be a code fault. But first I suggest you unlatch both latches, lift front of the top, and inspect the latch mechanism and the spots where they seat into the windshield. Could be dirt or grit interfering with the latch closure, making the car think it's not properly closed.

Also note, on the passenger side interior latch, there's a little black plastic pin or button that sticks out about 2 mm or so from the left side of the interior well where the latch sits when closed. I think this little bugger has something to do with the latch sensing system.

Sorry I can't help more ... running out of options ...

jeffjensen121

Tim, I will try the slot inspection. Both little latch pins (2mm) push in and out just fine. I want to thank you for all your help. Each step brings me a little closer to solving this. Quick note on how I acquired the car, A friend has a car lot, this car was collateral on another vehicle. owner defaulted and hid car for years, friend didn't want to deal with roof, figured I'd be able to get it working. Traded a Ford Excursion straight across for it.

Timroperco

Happy to help. I've had my Cab since about 1999, and its had it share of woes over that time -- water pump, tranny, window lifts. The most maddening was how my turn signals would go haywire, but only in summer. Turned out to be a $70 relay, as I discovered on this forum. I also tackled a problem I couldn't get a mechanic to fix -- replacement of a top lift hydraulic cylinders. MB dealer wanted $4000, I did it myself for about $400 (cost of cylinder rebuild). It's actually not that hard a challenge once you have the right tools -- the biggest headache is removing the rear interior seats and panels. But as I said, I was fortunate and didn't have any code faults or electrical problems (knock on wood). So she's still going nicely at 130,000 miles.

jeffjensen121

So...Can anyone else give me an idea where to start on this issue? The top keeps sensing that it is unlocked when it is not.

vexed

It sounds that way but it would be worth it to read and clear the codes (faults). That will tell you what the car thinks is wrong.

Floobydust

There are two micro switches attached to the latches located in the windshield header. One or both are either broken or disconnected. They both must be closed to tell the controller that the top is latched closed. Remove the header cover and inspect/test them. I believe I read somewhere that they can break easily.

Besides the obvious screws on the top and on the latch handles, there are to small screws hidden under the rubber weather strips on each side the must be removed as well. Should take no more than 15 minutes to open and inspect.

jeffjensen121

Thank you Floobydust. Yes, I checked and cleaned those, got the windows to roll down as they are supposed to, can hear pump running, but switch needed a lot of manipulation to accomplish this. Have a new switch on the way. One last question for now; How full should the fluid reservoir be?

kmoradpump@aol.

Could someone suggest if a standard 10 mm open end wrench will substitute for the tool kit top wrench?
Also, how do I find the radio code. My manual is in German.
Thanks kmoradpump

jeffjensen121

I don't know about the wrench, but your radio code may be hand written in one of your owners manuals. It is a 5 digit code. If not, you will have to call your nearest Mercedes dealership and give them your VIN #. This will enable them to look up the code for you.

jeffjensen121

Ok all, I have built my own blink code reader to check and clear faults in my top. Can anyone tell me which pins I should plug into in the footwell?

vexed

This should help.http://www.benzworld.org/forums/w124...ml#post4091215

When I built my code reader I used very long wires so I could still use the power and ground sources in the engine compartment.

Floobydust

Jeff -

Sorry for the tardy reply, but I've been out of the country traveling. I'm not sure what the fluid level should be in the pump reservoir, but as long as the pump is not sucking air, the fluid level is not the problem. BTW, does the roll bar go up and down? It is also driven by the hydraulic pump as well, so that may give a hint about whether the pump is supplying pressure.

I have attached with MB cabriolet top troubleshooting guide. I hope this and the code reader will help track down the issue.

- FD

jeffjensen121

FD,

Thanks for much for the info! And no worries on reply time, lol, I work 6 or 7 days a week, so little time for hobbies. So, yes, the roll bar goes up and down, so pump works. I have a feeling that it is just a matter of clearing codes. When I traded for this car, I knew the top didn't work. What I didn't know is that right before my friend acquired it, the fabric had just been replaced. The former owners swear the top worked just fine until replacement of fabric. I will keep you posted on progress and thank you again,
J-

Floobydust

Jeff -

If the top malfunction really did start when the fabric was replaced, I can almost guarantee the problem is with one of the several micro-switches that sense the position of the top mechanism. Most of these are in the top compartment area and are easily moved/damaged when something major like top replacement occurs. I have also posted the schematic for the top/rollbar controller here: top schematics to give you a better idea of the micro-switches involved.

Good Luck!

- FD

jeffjensen121

FB-

Sorry for my delay in saying Thank You. I finally took half a day from work today and ran the car to the dealership. They cleared the codes and tried to lower the top. The low volts code kept coming back. Any suggestions on where to start searching?

Thanks,

J-

joef

Have you tried moving the top with the car running? I had issues with trying to move the top just on battery power and had issues where it didn't want to move. I would try things with the car running first.

Floobydust

Jeff -

A "Low Volts" error comes from two sources. True low voltage - either at the battery or from voltage drops in the wiring. Or, from excessive pump current draw which is turn cases excessive voltage drop in the wiring.

With regard to the battery, check the battery voltage at the 30 Amp fuse described below while trying to operate the top with the engine running. It should go no lower than about 10 - 11 volts.

Power for the top systems comes through Fuse A (Bosch style) in the regular fuse box and through two additional fuses mounted on the "Axillary Fuse Holder" which is mounted on the right strut tower mount. There is a Bosch style 16 Amp fuse and a fusible link style 30 amp fuse. The 30 amp fuse feeds only the pump, while the other two feed everything else. Replace both Bosch style fuses prophylactically and inspect the 30 link. Make sure the Philips head screws are tight on the fusible link.

With regard to pump over current (which I think is most likely given what you have described), I can think of the following:

- One or more of the hydraulic solenoid blocks is electrically disconnected.
- One or more of the hydraulic cylinders has been re-connected with the lines hydraulic lines reversed.
- A blockage in the hydraulic lines - a kinked hydraulic line or dirt got into the system.
- The new top is binding somewhere, stalling the system.

Let us know what you find.

- FD

jeffjensen121

FD-

I think I have found the problem, but would appreciate your input. Had a Porsche mechanic buddy do voltage check. We started right at the pump. We disconnected the bracket from the pins on the pump and tested there first. When the switch is activated it gives proper voltage for up and down. But, with the pump connected, it only runs going up. Could it be the relay on the pump? Or could the pump be bad? I am awaiting a call from Klaus at Top Hydraulics for a more definitive answer, but you can never have to much info. As for the reversed hydraulic lines, how can I tell?

Thanks for any help. BTW, the pump leaks a little right at the brass torx screw on top.

J-

Floobydust

Jeff -

It could be a relay/pump issue, but I would doubt it. The reason is that the same relay closes whether the top is going or down. Same is true for the pump - it only spins one direction. The fact that you get voltage at the motor, if only in the up direction, tells me that the relay is good. The system does not sense the pump voltage, so even if the relay were iffy, it would not show up as a Low Volts error.

When you measure voltage with the pump motor disconnected, can you hear the relay on the pump click when you push the top switch to both up AND down? Or just up or just down?

When you measure voltage with the pump motor connected, can you hear the relay click when you push the top switch to both up AND down? Or just up or just down? What are the voltages that you measure? Is it ~12 volts up, and 0 volts down or something like 2 - 6 volts down?

Measure the pump voltage while connected and while operating the roll bar. Voltage ~12 volts both up and down?

Does the top switch start flashing if you hold it for ~5 - 10 seconds?

Can you lower the top part way manually? If so, will it go back up again under hydraulic control?

Lastly, I believe each hydraulic line is numbered and there is a corresponding number embossed on the cylinder at the correct port.

- FD

jeffjensen121

FD-

Thank you for the list. I will go over each step with a friend operating the switch. My friend was in the boot last time. We did not check voltage on the pump with the roll bar in operation.
Just checked the switch. It does not flash even when held for 30 seconds.
I can only push the top up about a foot before it refuses to go any further, but it has no problem hydraulically putting it back into place. I know the front latches are operating properly, but I see absolutely no movement in the cables next to the rear windows in either direction. Again, the tonneau lifts about half an inch, and I assume that is just from unlatching. I tried listening for the relay clicking, but the window motors were all I could hear (not enough time to remove covers). So Tuesday I will check the remaining items on your list unless what I have just mentioned gives you a definitive answer.

I really appreciate your guidance with this FD, just wish I had more time to devote to fixing this issue. Patience does not come easy for me, lol. I'd like to move on to some of the other issues I"d like to work on like running rich, rough idle when cold, and how do I check the vacuum system for the door locks since I have to unlock each door separately. Hopefully my shop manual arrives soon so I can tackle some of these myself . And while I have you for the moment, one quick question: In the row of switches and warning lights where the roll bar switch is, what is the one that is all black with a single red dot in the middle? It is constantly on and like the shop manual, I am waiting for the owners manual to arrive.

Thanks again FD,

J-

Floobydust

Jeff -

No problem - no hurry.

Your current post in combination with your previous tells me that the hydraulic pump and its associated relay are working, although pressure may be an issue. It seems like something else is locking out or preventing operation.

One thing caught my attention in your post - you said that "the tonneau lifts about half an inch." When you say tonneau, what piece are you referring to? Do you mean the rear top section like in my photo or do you mean the hard cover the covers the top storage compartment? I hope it is the former as the hard cover should not be able to move with the rear section in place. If the rear section is unlatching, have a friend push it manually up to the position shown in the second photo; then try to continue lowering the top. this will set the next microswitch and may allow the hard cover to unlatch and lift as shown in the last photo.

If the rear section releases somewhat, but not all the way so you cannot manually raise it as shown, the latch microswitch will remain closed and inhibit further operation. Causes of latch failure could be a leaky cylinder, misalignment, or low pump pressure.

Good luck.

- FD

jeffjensen121

FD-
Thanks for the clarification. What raises just a bit is the deck right behind the back seat. I do not see any movement outside the cabin. Klaus from Top Hydraulics suggested right side switch or possible incorrect fluid replacement after soft top replacement. BTW, I was searching older posts, love your cabrio! very nice. I am very interested in your radio replacement, what model/year is that. I would love to do the same.

Thanks,

J-

Floobydust

Jeff -

Thank you - I still consider my Cabrio somewhat of a work-in-progress.

I am still mystified by your top issue as the tonneau should not be trying to lift until the rear bow locked switch is cleared and the bow raised switch is set. This should be the case regardless of the reason for the bow latch failing to unlock. And, when the latch fails to unlock, the system should store a fault code - as indicated by the flashing top switch - when it takes too long for the bow to unlatch and raise. A Low Volts error is more consistent with the hydro pump stalling.

I'm kind of thinking more along the lines of a top controller issue. If the microswitches are in an out-of-sequence state, the controller will generate and "Microswitches Illogical" error (e.g., it knows the tonneau can't be open if the bow is latched).

I'm curious if the convenience module is speaking to the top module properly. Try the following simple test: With the windows up, start the car. Pull the top switch back two times quickly and the pull it back and hold it. All the windows should roll down. If the windows go down, push the top switch forward two times quickly and the push it forward and hold it. All the windows should roll up. If the windows don't go down with the first test, manually roll them down and do the second test. This will confirm that the two controllers are talking.

Lastly, if you get the time, try this: disconnect power to the pump, either at the 30 Amp strip fuse or on the pump itself (whatever is easier). Start the car; open the front latches and push the top up slightly as normal. Pull back on the top switch and hold for at least a minute or until it starts flashing. You will not damage anything because the pump isn't running. The code that is stored should be bow latch failed to unlock or bow failed/took too long to raise. I'm pretty sure that the top controller (unlike the ECU) only stores the first fault code discovered. This test should prevent a Low Volts code from hiding other codes. Still getting a Low Volts code would be telling as well.

As for the stereo, there are three parts to it. The head unit from a later year (2000 - 2002) W210 E class sedan; the D2B fiber optic buss iPod adapter is a Dension Gateway 500 (no longer made, but occasionally up for sale); and the speakers are the Jenhert speaker panels from Germany. The head unit is plug-n-play as is the Dension. The Jenherts are a special install, but I set them up to use the factory amps and wiring.

Keep us updated.

- FD

jeffjensen121

FD-

Thank you for the stereo info. Something to consider down the road...

Sooo.... I took a few minutes today and uncovered the pump, etc. Had someone else push the switch while I was in the trunk. The pump only runs when I try to raise the top. It does not run trying to lower it. Earlier I stated that the light does not blink when switch is set to lower. It does blink immediately on a single pull, stays lit on the double pull and all windows will go down and up with no problem. Pump runs fine both directions for the roll bar. Otherwise, nothing seems to be unlatching whatsoever. Again, the front end of the hard cover moves a bit. The 4 hydraulic lines I can see at the moment are in their correct locations, 54 to 54, etc. I did discover that one of the gas lift supports is missing and the other is shot.
Does any of this help? Tomorrow I will try to search out more lines, switches, etc..

Thanks,

Jeff

Floobydust

J -

I thought I had posted this last night, but I guess I had too much wine.

Try this very quick test. Start the car and while looking back at the rear bow, push the top down switch forward (e.g., up). You should see the rear bow push downward slightly. You may also hear the hydraulic solenoid click. If the pump is running and the solenoid block is working, you should see movement.

- FD