Hi
hope someone can help?
I recently bought a clk 430 convertible 2002 and needed to disconnect the battery to do some work. A week later I went to reconnect the battery and the boot wouldn’t open. Now I did check the boot opened with the key before disconnecting the battery but now it won’t open. I have had the rear seat out and no way through. I also connected a battery to the engine bay and tried the remote and no joy. Assume because negative terminal disconnected that won’t work. Am I right in thinking the only other way is to smash the rear tail light at least then I should be able to get my hand in and reconnect the battery?

Any help appreciated

Cheers

 

You just need to remove the mechanical key from the fob, which will override the pneumatic central locking system, to unlatch the lock and open the truck (see owners manual).

 

Thanks for the reply but the key won’t open the lock so there appears to be no way to enter the boot to reconnect the battery. Hence I’m thinking about breaking the rear light to gain access

 

OK........You seem very determined to smash your rear tail light, to get your hand in to reconnect the vehicle battery, which is an invasive (e.g. destructive/unnecessary/expensive assembly to replace), not to mention will more then likely prove to be not be unsuccessful.

By design. MB provided a method of open the trunk, using the mechanical key when the vehicle battery is either disconnected or discharged.

That said, while the vast majority of owners who experienced issues with the mechanical key not working, have all been previously been solved in numerous existing forum thread explanations.

If the mechanical key doesn't work as detailed in your cabriolets owner manual, explain why.

However, if you should you still be unable to open your trunk thereafter, within this forum you'll find a thread that will explain how to open your trunk , non-invasively, in great detail.

 

I got a 211 trunk open with a broken key cylinder by jumping power to the fuse block under the hood.

On the right side, there are several large wires coming from the rear to the underhood boxes, I used a screwdriver on my positive clamp of my jump box to touch one, then grounded the other side to the chassis, and got enough power to electrically release the trunk and reconnect the main battery.

 

Thanks joe have tried that method but won’t work. The negative terminal as disconnected so assume that’s why it’s not working.

Serndipity the car is 19 years old and came with no service history or owners handbook and needs a lot of work. I’m not determined to smash the tail light hence I’m on the forum looking for help. From what I can find on the form there is limited options as the battery is disconnected and the key won’t work in the lock despite numerous attempts

Thanks

 

Are your back seats locked?

 

Have removed back seats and no access to the boot from what I can see

 

No, you can have the battery fully out of the car and it will still work. You just gotta find the right place.

 

On both the W208 and A208, there is a small plastic box, located between the windshield washer tank and F1 fuse box.

Under it's cover you'll find the hot lead terminal, where you can apply 12 volts to the vehicle electrical system, which will then allow opening the trunk, via the fob or center console switch.

Notes:

When done correctly, you'll immediately be able to see some of the cabin lamps illuminate, but the stored vacuum in the reservoirs may be insufficient, so it may take a few minutes longer for the auxiliary electrical pump to build sufficient pressure for the central locking system to operate.

Also on the A208 cabriolets, by design (e.g. to prevent potential collisions between trunk lid and tonneau cover), whenever the soft top is not properly closed and locked, or open and locked, the the central locking system will block the trunk from opening and you'll have to use the mechanical key.

To use the mechanical key, insert the key, turn the tumbler 45 degrees counter clockwise and then push inward (e.g. it's the push inward that will mechanically unlatch the trunk lid).

 

Unfortunately this is the terminal I have used since day one and no joy whatsoever.

 

What is the specific capacity of the 12 volt source that you're connecting to that terminal (e.g. trickle charger, full size vehicle battery etc.) and/or using as a vehicle ground return?

 

Hi i’v been using another car battery and also my jump starter pack that has a 350a starting current which peaks at 500a

The only thing I’m thinking is will this method 100% work with the negative battery terminal disconnected?

Also do I need the battery connected for a longer period thought it would work straight away if not after a few minutes. Should I try leaving it connected for an hour?

Unfortunately I can’t jumpstart the car from a running vehicle as can’t get another vehicle in where the car is located but would thought the methods above still should of worked

i have used various parts of the body as a ground and has made no difference sadly

cheers

 

This method will still work even with the negative terminal disconnected from the battery in the trunk.

There are 3 cables connected to the positive terminal of trunk battery. The large black cable is routed through the vehicle's left interior and supplies all consumers (electrical equipment), except those in the trunk's fuse box, which is fed power by the small black cable.

Access to the other end of this large black cable is available at the terminal inside the small plastic box in the engine bay.

Therefore when you connect a 12 volt power source between this terminal and vehicle ground, you have essentially installed an auxiliary battery to the vehicle's electrical system (replacing the disconnected trunk battery).

In your situation, because your trunk battery has been isolated from the electrical system, the replacement power source should be capable supplying between 11 (minimum) and 14 (maximum) volts at sufficient current (amperage) to operate the electrical equipment required for the central locking system to open the trunk (via the fob or center console trunk release switch).

Another car battery would be best, to prevent an over voltage condition that some battery chargers present.

Also note that the battery's electrical power is distributed throughout the vehicle, using 4 different electrical circuits, based on the position of the ignition switch.

15 = switched battery power, hot in positions 2 & 3
15R = switched battery power, hot in positions 1, 2 & 3
30 = unswitched battery power
87 = powered via a specified relay

As noted in (post #10) above, there were some important caveats pertaining to the central locking system, vacuum requirements and soft-top being locked.

The central locking system and pneumatic pump are both fused with fairly high amperage fuses, which is why a questioned what you were using for a the power source, as well as it could take some time for the auxiliary electrical pump to build sufficient pressure for the central locking system to operate .

When you first attach the auxiliary battery, with the ignition off, when you open the door, the dome lamp should illuminate. As you turn to positions 1 and 2, additional circuits become powered. For example, in position 2, most of the instrument cluster lamps will illuminate.

To rule out the possibility that the central locking system is blocking the trunk from being released, when you turn initially turn to position 2, keep an eye on the center console operating switch, as it's lamp should turn on briefly for only 1 or 2 seconds (while the soft-top controller runs a builtin self test diagnostic) and then turn off. If it remains illuminated, the controller found a problem such as the roof not being properly locked.

 

Thanks will try again but despite numerous attempts I have had the dome light has never come on and the ignition won’t turn.

 

That explains why the method we've been discussing to open your trunk hasn't worked, due to faults pertaining to your Drive Authorization System , which operates as described in the below document.



In closing, if you click here, you will a noninvasive method to unlatch the lock mechanism and open your trunk without causing collateral damage to your 2002 CLK cabriolet.

 

Paint is an insulator connect the negative to the hook on the engine to complete the circuit circled in red. Remove the engine cover to access.

 

Well after nearly 2 weeks of trying to get the boot open I have had to force entry but at least i’m in.

There is a great write ups on taking the boot lock apart to get it working again. Just struggling how to get the lock cylinder out of the mechanism. Have removed the plastic parts and the snap ring and still won’t come out. Any ideas ?

Thanks again