Trunk
Opening the trunk lid
A minimum height clearance of 6 ft. (1.85 m) is required to open the trunk lid.
Unlocking and opening the trunk lid using SmartKey
Press and hold trunk lid unlock button (2) on the SmartKey until trunk unlocks and begins to open.
If the trunk lid does not open, it is still locked separately (see below).
Opening the trunk lid from the inside
You can open the trunk from the inside if the vehicle is stationary. The switch is located on the driver's door.
- (1) Indicator lamp
- (2) Remote trunk lid release switch
Pull remote trunk lid switch (2) until trunk begins to open. The trunk lid opens. The indicator lamp (1) comes on and remains lit until the trunk is closed.
Even with the SmartKey removed from the starter switch or the SmartKey with KEYLESS-GO removed from the vehicle, the remote trunk lid switch can be operated.
If the vehicle was previously centrally locked, the trunk lid will lock automatically when closed. The turn signals will flash three times to confirm locking.
Opening the trunk lid using emergency release
The emergency release button is located on the inside of the trunk lid. Briefly press emergency release button (1). The trunk unlocks and the trunk lid opens. The emergency release button unlocks and opens the trunk while the vehicle is standing or driving. The emergency release button does not open the trunk lid if the vehicle battery is discharged or disconnected.
Illumination of the emergency release button:
- The button will flash for 30 minutes after opening the trunk.
- The button will flash for 60 minutes after closing the trunk.
If the emergency release button is pressed and the vehicle was centrally locked, the exterior lamps will flash and the alarm will sound as the trunk lid opens.
Opening the trunk lid from the outside
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The trunk lid open button is located in the rear license plate recess. Press the outer left-hand side of trunk lid button (1). The trunk lid opens.
Vehicles with KEYLESS-GO: If the vehicle was previously centrally locked, the trunk lid will lock automatically after closing it.
Closing the trunk lid
Warning: Do not place the SmartKey in the open trunk. You may lock yourself out. Vehicles with KEYLESS-GO: To prevent a possible inadvertent lockout, the trunk lid will open automatically if a SmartKey with KEYLESS-GO is recognized inside the vehicle or in the trunk.
Closing the trunk lid using handle
Lower trunk lid by pulling firmly on handle (1).
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In addition to handle (1), facelift vehicles can be closed using extending handle built into the trunk lid handle (2). Push the trunk lid down gently at the extending handle (2) until it engages into the lock. The extending handle (2) is retracted after a few seconds. The power closing assist automatically ensures that the lid is pulled closed completely.
Trunk lid closing system
On vehicles with option code 881 - REMOTE TRUNK LOCKING the trunk lid can be closed by a press of button.
If the trunk lid comes into contact with an object while closing (e.g. luggage that has been piled too high) in the upper motion sequence, the closing procedure is stopped and the trunk reopens slightly.
The trunk lid opening height can be limited when transporting goods on a roof rack (e.g. presence of an MB sport luggage container). When activated, the trunk lid opens to approximately the height of the roof edge. You can activate the limiting opening height of trunk lid using the control system.
The closing procedure can be stopped at any time by pressing the trunk lid closing switch (on the driver's door), the trunk lid closing switch (1) or the "trunk lid unlock" button on the SmartKey.
Closing from the outside
Press trunk lid closing switch (1) briefly. The trunk lid closes.
On vehicles with trunk lid closing system and KEYLESS-GO, you can close the trunk lid and lock the vehicle simultaneously using the second button on the switch.
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Make sure you have the SmartKey with KEYLESS-GO with you. Press trunk lid closing switch (1) (in the second picture) briefly. The vehicle is locked and the trunk lid closes automatically. The turn signals flash three times to confirm locking.
Closing from the inside
The trunk lid can be closed from the inside using the opening switch if the vehicle is stationary.
Press remote trunk lid switch (2) until the indicator lamp (1) goes out and trunk lid is closed. To interrupt the closing procedure release remote trunk lid switch (2).
Trunk lid additional locking mechanism
Vehicles equipped with option code 884 - TRUNK LID ADDITIONAL LOCKING MECHANISM (HZS) have a function permitting the separate locking of the trunk using the mechanical key. If present, this feature can permit you to deny any unauthorized person access to the trunk by locking the trunk separately and leaving the SmartKey less the mechanical key with the vehicle.
To verify the presence of this feature, use the mechanical key to lock the trunk and then attempt to open the trunk by pressing the trunk lid button after the vehicle has been centrally unlocked with the SmartKey. The lock is located next to the recessed handle.
Close the trunk lid. Pull the mechanical key out of the SmartKey. Insert the mechanical key into the trunk lid lock. Turn the mechanical key clockwise to vertical position. The trunk remains locked even when the vehicle is centrally unlocked. You can only cancel the separate trunk locking mode by means of the mechanical key.
Trunk lid
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Trunk lid covering
There are differences between pre-facelift and facelift vehicles in how trunk lid covering attached to the trunk lid.
Pre-facelift
Pre-facelift vehicles (To Date: 01/09/2002) have lid covering A2207500081 which is attached to the lid with two screws in center tightened from outside and 7 screws tightened from inside.
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Facelift
Facelift vehicles (From Date: 30/09/2002) have lid covering A2207500281 which is attached to the lid with one bolt in center tightened from inside and 8 retaining clips. The covering has also different trunk lid handle opening modified for retractable trunk lid grip.
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The U.S. version A2207500381 has smaller distance between licence plate mounting holes.
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Locking Mechanism Actuator
W220 trunk lid actuator is pneumatically controlled and can have some or all of the following functions:
- Auto opening (all vehicles)
- Auto or self closing (vehicles with option code 881)
- Extension and retraction of trunk lid handle (facelift vehicles)
The positive and negative pressures required for the pneumatic control of the Trunk/Boot Lid functions are generated by the Pneumatic System Equipment (PSE) Pump.
Part Numbers - Trunk Locking Mechanism
- Whole Assembly - Trunk Locking Mechanism Actuator 220 750 06 84, 2207500684.
- Vacuum Servo Only (Black) - Trunk Locking Mechanism Actuator 220 750 01 85, 2207500185.
- Air Servo Only (White) - Trunk Locking Mechanism Actuator 220 800 05 75, 2208000575.
Issues
Common issues relating to the trunk/boot lid functions are;
- Hissing Sound on Trunk Closure
- Broken or Failed Pneumatic Actuators
- Cracked or broken pneumatic lines.
- Cannot remove the actuator rod to get the locking mechanism out of the trunk
- Open the trunk when the battery is dead
Opening the trunk when the battery is dead
Issue: A completely dead battery prevents the boot lid from being electrically opened. A jump start is not possible if you cannot access the battery as the W220 does not have accessible jump ports.
Solution: Extract the mechanical key from the SmartKey and use it to open the trunk. If that doesn't work you may have to charge the battery prior to jump starting the car.
- Pull the carpet back from the top under the front passenger side dash.
- Behind the Styrofoam insulation there is an aluminum plate.
- Unscrew the 3-4 bolts to get to the positive terminal.
- Hook up a charger and charge the battery as long as possible.
- After a while you should be able to start the car.
- If the trunk still will not open reset it by removing the 20A yellow fuse from under the rear right passenger seat fuse box.
- Leave it out for about 5 mins.
- Then put it back in and then try to open the Trunk.
- The Trunk should now open.
DIY - Removing Trunk Lid Lining
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DIY - Removing Trunk Lining
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Opening trunk without key
To open the trunk if for some reason it cannot be opened using smartkey or mechanical key, you can use this method which will cause only minor damage of lid covering.
- Detach the licence plate from the trunk lid covering.
- The covering (9) is a big plastic part mounted on the lid. Remove the covering:
- Pre-facelift:
- You will see two screws in the middle of covering (9). Remove them.
- You have to remove covering by force using plastic molding remover tool. Note, that there are 7 bolts (10) that are tightened from the inside to hold the covering (9) in place. You will damage plastic housing for these bolts in the covering. However, it is very common to see these housings already damaged. Furthermore, the covering holds to the lid just fine only using the two central screws.
- Facelift:
- Note, that there are 8 clips (10) and one bolt in the center tightened from the inside that hold the covering (9) in place. You have to drill off the head of center bolt holding the covering. This bolt is not crucial, since the covering holds to the lid just fine using only the clips.
- Pre-facelift:
- After covering is removed you will see three T30 torx bolts (12) holding the trunk lid handle. Unscrew them.
- Push the whole trunk lid handle inside through the hole while pushing the button.
- You will hear the pop noise. Trunk lid is open.
- In case the release rod (14) that connects the trunk lid lock (1) to the trunk lid handle (13) is disconnected, you can use a needled nose pliers to release the rod and open the trunk.
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Welding trunk lid covering holes
Trunk lid has 7 (pre-facelift) or 8 (facelift) holes which are used to attach the trunk covering (9) to the trunk lid. It is common to see these holes being a source for moisture and rust inside the trunk lid. As an anti-rust measure these holes can be closed by welding. The trunk covering still remains attached to the trunk lid by two central screws (pre-facelift) or one central screw (facelift), although double sided type is recommended to prevent vibration of the covering.
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DIY - Repair of Broken Pneumatic Actuator 01
With thanks to BenzWorld member 'subscriber' for posting an excellent description of his repair of a broken locking mechanism pneumatic actuator.
Note the broken plastic tabs on the perimeter of the actuator.
See http://www.benzworld.org/forums/w220-s-class/2532833-repair-part-220-750-0684-trunk.html
DIY - Repair of Broken Pneumatic Actuator 02
See WIS 88.52 Retractable Trunk Lid Grip (RTG) for a DIY repair of a broken actuator.
DIY - Repair of Pneumatic Actuator Pneumatic Solenoid Valves
Pneumatic Actuator Pneumatic Solenoid Valves
In the Pneumatic Actuator there is a double solenoid valve which distributes the pneumatic pressure to the relevant actuator depending on the required result.
The exact description of which coil does what has yet to be determined and wasn't necessary for a thorough clean and bench test. It is something like the following: (Reference: HECK function on Pneumatic System Equipment (PSE) Pump.
- When the Boot/Trunk Lid is closed manually to the first position as identified by a loud click, the PSE HECK port provides +ve pressure (27KPa or 4psi) to the Boot/Trunk Lid Solenoid Valve Assembly and hence to the Large White Actuator which pulls the boot closed tightly, then the PSE HECK port changes to –ve pressure (19”Hg vacuum), which retracts the Handle (RTG), then returns the line to atmospheric pressure.
- When the Boot/Trunk Lid is commanded to open either by remote control on the key fob, by pressing the Boot/Trunk Lid button, or by pulling the internal Boot/Trunk Lid release button on the driver's door, the PSE HECK port provides +ve pressure (27KPa or 4psi) to the Boot/Trunk Lid Solenoid Valve Assembly and hence to the Small Black Actuator or "Hockey Puck" which opens the locking latch, thus releasing the lid which fully opens. +ve Pressure is also applied to the RTG Handle, which extends the Handle. After all this is finished the pneumatic line returns to atmospheric pressure.
DIY Clean and Regrease - Trunk Lid Actuator Pneumatic Solenoid Valves
Once the Boot/Trunk Lid Pneumatic Actuator is removed from the vehicle it can be dismantled on the work bench. See WIS 88.52 Retractable Trunk Lid Grip (RTG) for the removal method.
- Press in the two small plastic tabs and the Pneumatic Solenoid Valve Assembly can be with drawn.
- Remove the top front cover over the electrical connector.
- Then press in two small plastic tabs and remove the top rear cover.
Photo of disassembled Pneumatic Solenoid Valve Assembly
Closeup of coils and seals.
The electrical circuit diagram is very simple with the two coils just connected in parallel. A diode is also connected across the coils to reduce current surge when the coils are switched off. (Here is the theory: The magnetic energy stored in energised coils can generate a large spark across the operating switch when it is opened and consequently burn the electrical contacts in the switch. A diode provides a path for this excess energy to dissipate harmlessly.) The downside of having a diode in the circuit is that the electrical contacts are now polarised and correct polarity of any applied test voltage must be observed otherwise the diode will burn out. This just means that the '+' and '-' signs on the next diagram must be observed when applying a 12 Volt DC test voltage.
Circuit Diagram of Trunk Lid Actuator Pneumatic Solenoid Valves
- Reassemble in the reverse order but apply silicon dielectric or vacuum grease to the pneumatic seals before assembly.