I will stick some leads in that pin and check! Appreciate the help!

 

At pin 21 on C1 I get a steady 3 volts (doesn't go to ground 0 volts) and the electronic trunk lock doesn't work at all

 

I"m thinking the trunk lid is not indicating that it is closed. Im just not sure where that wire is.

I BELIEVE all of the following is the way it works:
The "trunk lid open/closed" indication goes to the Body Control Module - to turn the dome / trunk lights on and off.
That output (to the lights) has I timer in it, the timer is in the BCM.
The BCM then goes onto the CAN bus and tells the Top Control Module the status of the trunk.

Have you downloaded the manual? It is time to! I did so a LONG time ago and I THINK this is what I'm using:
http://www.jodykrivohlavek.com/_docu...ice_Manual.pdf

 

If you open either car door, the dome light should come on, then go off with closing the door.
The same better happen when you open and close the trunk lid.

If the trunk lid does not cause the light to go on and off properly, you may be onto it. I cannot determine if the "Liftgate Lock Indication" is an indication of:
1) The pnuematic lock position (that activates with the key fob - and the central locking pump)
2) The electric lock position (that activates by command of the Top Control Module)
3) The closed/open status of the trunk (if so, it is named wrong)

There is, somewhere, a switch that tells the car (telling either the Body control module or the central security module) the status of the trunklid's open/closed position. What ever module gets that wire, that module then uses the CAN bus to tell the Top module that the lid is closed and it is OK to electrically lock the lid and start the pump.

 

When I scanned the car today there was a code...1040 - no CAN communication with ECU. Does that mean anything to you?

 

I don't think P1040 is a Mercedes-defined code. Where did you get that definition?

 

I pulled that code with exact description out of the cars computer with my scan tool...it isn't a "P" code

 

It appears I may be having more issues than just the top not working...when checking the interior lights on/off with the doors, it appears that isn't working properly either. With the light switch in the top of the windshield header slid to the right hand position, the lights just stay ON and do not go off with the doors or when you hit the lock button on the remote. With the light switch slid to the left hand side, the lights just stay OFF all the time. I also notice now that the door locks work every time (lock/unlock) when using the remote HOWEVER not when using the door lock switch on the dash. I am beginning to think that my issue just may be that central locking vacuum pump box that was once full of water!

 

Lots has developed and progress made in the time it has taken me to get this darn virus protection software updated and everything restarted.

It probably is more than this given the other problems now noted but early in the post I read references to the truck top boot being "UP". If this is the bag like structure that the lowered top goes into it should be DOWN not "UP".

I hope you get that top down before the weather gives out.

 

are you referring to the tonneau cover being up? If so, mine doesn't go up or down right now...nothing happens when I hit the switch it just beeps!

 

Looking in ALLDATA I can see that C1 (white plug) on the central locking pump/security system module has wires for the following...
Pin 8 - CAN B Bus (+)
Pin 9 - CAN B Bus (-)
Pin 13 - Liftgate lock switch sense (unlock)
Pin 14 - Left door ajar switch sense
Pin 16 - Right door ajar switch sense

 

I am not referring to the hard tonneau but rather to the fold up bag like structure in the truck that can be folded up to allow for more baggage in the truck when the top is up BUT will prevent the top from lowering if left in the up or closed position.

I leave my top down so cannot tell you too much about it but it is accessible from the truck area and is below the top. It is what the top goes into when it is lowered.

 

He has verified the divider and top open switches. We are looking at some other conflict here.

(This guy is the FIRST person to come here looking for help that was willing to get a meter out and check voltage levels!!!! This will get fixed!)

Yea, you are making it sound like your "top problem" is actually a problem elsewhere - and this is VERY possible.

 

That happened to my wifes 05 roadster and it had the same symptoms you are talking about it was the big expensive central locking box that is in the lowest part of the trunk we replaced that and everything went back to mnormal. we now keep the lock box in the main part of the trunk in a plastic box to keep it from getting wet

 

We can pursue the manual all day long - but I'm not sure that anything beats experience.

 

At this point I believe the problem exists in the central locking vacuum pump box so I am going to order one. I will definitely post the outcome once it comes in. Thanks for all the help and guidance...I really appreciate it!

 

***UPDATE***
I replaced the central locking vacuum pump box and EVERYTHING WORKS!!! I appreciate everyone's help and time with diagnosing this issue.

 

Cool ! question.. did that rectify the interior dome lights too? Wife's car has no other issues other than this light and exit courtesy lighting (fogs-marker) .. "Ironically" we went to cars and coffee in Dallas a couple weekends back. It was still dark so had the headlights on. We parked and I got out of the car .. and while standing there noticed the rear side marker lit.. Hmm.. could have sworn I turned the lights off.. opened the door and sure enough..off. Well okay then.. Later that evening stopped off for coffee.. exit courtesy worked again! Well maybe she just missed Texas? (that's her "origin").. after getting coffee flipped the interior switch over to "on/automatic".. and they stayed lit.. 2 blocks over to motel and no exterior exit lights once again.

 

it did also fix the issue with the interior dome lights as well as the door lock/unlock switch on the dash...everything works perfect again

 

Hello
Ive gone through this entire thread and I believe you might be the person to help me. Ive got almost the same problem here and following the order/sequence of actions that should take place bringing the top down, I'm now stuck at the point where the electronic lock activates but top doesn't go down. I don't hear any pump running and I don't really know how to proceed with fixing the problem. Can you please help?