I_am_Sam

Hi all,
So I've been having this issue for a while.
RHD Australian CLK 320.

The issue:
After what seems like a random period of time, from half a day to a few months, the seat belt presenters will no longer extend. Both sides.
(Rear right window, will also not go down, but will go up)

The temporary fix:
Pull fuses 32 and 33, wait a few sec and replace.
Now seat belt extenders and rear window all work as they should.
However, I don't know for our long.

Does anybody know the reason this occurs so I can make it a full time fix?

Thanks!

Lloydchiro

I have found that for several faults on my CLK, I have to clean electrical contacts at the fuse, or at a light socket, or other electrical connectors (third brake lamp.)

Get some electrical cleaner, and spray the surfaces. Maybe wipe the surfaces of the fuses with a microfiber cloth.

I_am_Sam

Thanks, but did not help in this instance.
The time period between pulled fuses and retractors and window no working is now reduced to 5 minutes or less every time.

Any other thoughts on this one please?

I_am_Sam

Hello all,
Unfortunately this issue still plagues me! I was going to replace the control box/module and see if that fixes it.

Would someone know if the: CONTROL UNIT (REAR CONTROL UNIT) A2098205926 (previous part numbers A2098205226, A2098200326), is the control box/module that handles the the seat belt extender operation (and rear right window).

Thank you!

I_am_Sam

SOLVED:
Replacing the Rear Control Unit has fixed my issue.
My part was: A209 820 03 26 [02]. HW20/01 SW: 35/01 Q3
Replaced with: A209 820 03 26 [02]. HW01/02 SW:06/03 Q5 (from a donor CLK500)
Changing this part, also fixed a parasitic battery drain!

Long story (may help others diagnosing):
So as per above posts, this failed slowly over time, until the extenders would only operate for a few minutes after battery reconnected or fuses pulled - enough time to either get stuck extended (annoying) or to get them to retract.
I also developed a parasitic battery drain, where the battery would go flat if the car was not driven much. It would be fine if driving to and from work, but weekends with not much driving it would not start come Monday morning.
However as this issue also didn't just start immediately, and I put in an after market radio at some point, I didn't relate the two issues.
So the battery drain was really annoying me so I decided to do some tests as YouTube videos describe:
- Disconnect battery
- Clamp the door switch closed (so you can access the internal fuse box) without activating internal lights and whatever else might turn on
- Use a multimeter in series with the battery to monitor current
- Disconnect fuses to try to isolate the issue
- However when I did this, the current was 0.06A then 5 minutes later 0.02A. Which is very low and would not cause a battery drain - so I was stumped. I still pulled all fuses but current reading didn't change.
- But here is where I was lucky, I opened the boot/trunk (YouTube says not to as you might get a large current spike that will kill your multimeter...I was out of ideas so I just did anyway) because there are also fuses in the boot/trunk, which did cause a spike, so I decided to close it promptly and make sure my multimeter survived - which it did, but now the multimeter was showing 0.1A and after 15 minutes it remained. (I even unlocked and relocked doors just in case an immobiliser or alarm or something along those lines was activated, but current remained high)
- Then I pulled both fuses 32 and 33 and the current dropped immediately (note, it has to be both fuses, one or the other did not affect the reading), putting the fuses back in did not cause a spike, and the car did its 0.06A then 0.02A
- As those fuses are listed in other operations of the car, I thought the final thing I would try is to disconnect the control module and try the the above again. This time opening the boot/trunk did not cause the current to stay high and the car went back to 0.02A after 5 minutes.
- I replaced the module with a used one off eBay. The extender arms and window are working fine now. And testing the current as above it shows the car also goes back to 0.02A in its sleep mode.

Conclusion: The rear control module failed over time and would also cause a battery drain when it was activated

I hope this is of help to someone!

digitalstorm

Hi, I am also having trouble with the seat belt presenters. When replacing your module did you need to reset any other functions in the car? Or is it just plug and play?

thx

PATRIOT USA

Butterfly is the Italian greyhound behind the wheel. She can almost outrun it.


I have a 2005 CLK 320 CABRIOLET with less than a 100000 miles on it, but I had to replace the door actuator on the passenger side.I don't know why it just became whatever and the door would not catch and stay closed.Fly open turning a corner.
During that week of absolute hell doing that thing by myself I lost some of the screws to put the panel back on. The Warning light for the open door would come on and off constantly.And it finally stopped doing that once.I found the screw that goes in underneath the hand pull, and got that tightened up however. Just the other day.I closed the door from From the driver's seat and when I did it pulled the screw out of the door because in all my brilliant mechanical aptitude used a too small screw. Then a couple days later both the seatbelt presenters stopped working . So I spent several days dealing with trying to figure out what was wrong with the seatbelt presenters and on a lark decided to replace the screw in the door that had come out. I lost the screw out underneath one of the vehicles that there.I can't find it but anyhow.I've got the panel back on completely perfect so that it is very flush All the way around. The top edge of the door panel when viewed from outside showed a hint of particle board type material running the lenght behind the top of the rolled down window. I pulled up tge door panel and towards the outside and had to use a soft hammer to get it back completely in sync as before i messed with it. low and behold both seatbelt presenters started working then. So I don't know.I would suggest to check thePosition of your door panels and make sure that they are perfectly lined up with everything.Because that's what was Screwing up the Seatbelt presenters on my baby. I love this thing

I_am_Sam

Plug and play.

I_am_Sam

Plug and play.

tenpin

Where is the seat belt extender control module located?

I_am_Sam

In the trunk/boot. Left hand side wall. Behind the carpet/trim.