WIS 88.52 Retractable Trunk Lid Grip (RTG)

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Description - Retractable Trunk Lid Grip

Facelift vehicles without option code 881 - REMOTE TRUNK LOCKING have a hidden handle which appears whenever the boot/trunk lid is opened. The handle is chrome plated and is pneumatically controlled. It is called the Retractable Trunk Lid Grip (RTG).

The Retractable Trunk Lid Grip (RTG) is used to pull down the boot/trunk lid for easy closing. According to M-B the hidden handle was provided to avoid the operator having to touch a wet handle in inclement conditions. STAR DAS refers to it as the "dirt free handle".

  • Photo of a W220 2003 (Update) S500L with Retractable Trunk Lid Grip (RTG) in hidden or retracted position.
  • Photo of a W220 2003 (Update) S500L with Retractable Trunk Lid Grip (RTG) in open or extracted position.

The positive and negative pressures required for the pneumatic functions are obtained from the Pneumatic System Equipment (PSE) Pump and specifically the 'HECK' port.

Function - Retractable Trunk Lid Grip

Opening Trunk

When the Boot/Trunk lid is opened by either remote control on the key fob, using the driver’s door trunk release switch or pressing the switch on the trunk lid, the Pneumatic System Equipment (PSE) Pump applies positive pressure to the latch mechanism which unlocks the latch, releasing the lid which fully opens and also extends the Retractable Trunk Lid Grip (RTG) handle. The RTG stays in the extended position until the trunk is closed.

There should be no hissing sound of air escaping during this operation. If there is a hissing sound for even one to two seconds see the Issues Section below.

Closing Trunk

When the Boot/Trunk lid is manually closed by pulling down on the RTG Handle until the latch goes click, the PSE applies positive pressure to the latch mechanism and pulls the lid closed.

Six seconds later the RTG is moved to the retracted position by the PSE pump applying negative pressure to the latch mechanism. (Note if the RTG has a leakage issue and a hissing sound of air escaping can be heard the RTG handle can take much longer (17s has been observed) to retract.)

Issues - Retractable Trunk Lid Grip

Hissing Sound on Trunk Opening or Closure

This issue applies to vehicles with auto closing trunk and later ones post facelift 2003 which if they don't have the auto close feature have the Retractable Trunk Lid Grip (RTG) or retracting chrome handle feature.

When the boot lid is opened there is a hissing noise due to air escaping as PSE pump applies positive pressure to the latch mechanism. This is not normal.

After the boot lid is closed there is a hissing noise due to air escaping as the lid is pulled down tight and then the chrome handle retracts. This is not normal.

Hissing Noise Cause

A persistent loud hissing noise once you open or close your trunk even for one to two seconds is not normal and usually means that you have a leak in the trunk lock actuator, the RTG actuator, the yellow pneumatic hose or fittings connecting the PSE Pump to the locking mechanism, or the orange pneumatic line or fittings connecting the locking mechanism to the RTG.

It will eventually stop leaking once the leak gets worse. Hopefully the pump will recognise that it is running for too long and will stop working so that it doesn't burn out. Then the trunk stops sucking down. Do not leave in this condition for too long because when the trunk stops sucking down water can get in and ruin your electronic components in the left side of the trunk behind the panels. There is also a possibility of damaging the pump due to constant running.

Repair Hissing Noise

Often the hissing is caused by a crack in the yellow pneumatic line that is located inside the black braided plastic harness which is easily visible on the inside of the trunk towards the rear window. You can see it when the trunk opens and closes. For whatever reason M-B used a very stiff pipe which cracks easily.

A common mistake is that when you have some aftermarket installation such as a reversing camera, the installer runs their wires alongside the harness, and adhere their wires to this with the additional strain causing premature failure of the stiff pneumatic line.

A simple fix is to use a rubber hose to cover the crack and seal it with adhesive, sealer, tape and plastic ties.

W220_Repair_of_Yellow_Trunk_Vacuum_Hose.JPG

Reference: http://www.benzworld.org/forums/showthread.php?t=1761754

If the hissing is caused by a broken actuator mechanism it is possible to apply a temporary fix by reinforcing the actuators with twitching wire and plastic ties. But be aware that the forces generated by the PSE Pump are considerable and the best method to achieve a repair is to replace the actuators with new ones. Second hand actuators will most likely be just as stressed as the broken one you are replacing.

Trunk/Boot Lid Handle Removal

It is difficult to remove the actuator rod out of the trunk locking mechanism without breaking the plastic that surrounds it.

Caution Be careful as if the rod is not replaced correctly and securely, the trunk can lock and may not be openable with either the key or with the remote.

Method

  • Disconnect the battery earth connection.
  • Remove the trunk lid lining as per DIY - Removing Trunk Lid Lining
  • Note that the rod end is placed between one black plastic piece that has screw thread on it and another piece that is like a small latch door.
  • Mark the position of the actuator rod with masking tape.
  • Make sure to remove the actuator rod at the end closest to the pneumatic actuator or "hockey puck". Some BW Members have spent hours trying to pry off the ball joint end, and finally yanked on the other end to find it came out relatively easily.
  • The latch door can be opened with a wide flat head screwdriver. Carefully apply a strong steady force.
  • Once the latch piece "swings away", the metal rod can be pried out of the plastic piece. The key is to be gentle and patient. It is a good idea to place a spacer behind the rod to hold it in place when applying finger pressure to the plastic tab.
  • Once the rod is removed, remove the pneumatic actuator or "hockey puck". Caution because if the rod is not replaced correctly and securely, the trunk can lock and may not be openable with either the key or with the remote.
  • Once the rod is released the whole actuator can easily be removed from the trunk lid. It is far easier to attempt a repair on a work bench than with the unit still in the car.
  • Mark the position of the two Torx screws holding the latch mechanism in place. This makes for easier reinstallation.
  • Remove the two Torx screws and allow the whole actuator assembly to hang down into the trunk.
  • Note the colours of the pneumatic lines and the position of the black and blue electrical connectors before disconnecting them.
  • Move the whole assembly to a work bench.
  • At the lock mechanism where the rod attaches, take a screw driver or needle nose pliers and gently wedge between rod and plastic slot where the rod attaches.
  • Gently pry the rod out of the slot.
  • Once the rod is released you can then pull the lock mechanism down so you can access the puck. This isn't hard, but a word of warning! There is a little electrical plug that attaches next to the puck. If you unplug it, make sure your fingers are not next to the lock latch as it will put a death grip on your finger.
  • The puck is press fitted into the lock housing and again can be detached by gently prying with a small screwdriver to release.
  • Once the puck is detached if the air line is still attached it can be removed if required to bench work the puck. Instead of detaching the airline at the puck just pull the hose off at the attachment point at the puck. It is easy to understand when you get the puck released from the housing.
  • Unless you have a replacement puck, then you must attempt to reseal.
  • Reseal by compressing the puck then using a two part sealer. Coat the seam around the side of the puck where it was leaking, 360 degrees.
  • Let it cure for a few hours.
  • Wrap "high speed" tape over the seal.
  • Add more tape over the top and bottom to fortify the bond.
  • Here is an example of a less elegant solution by BenzWorld member 'ricebubbles'. Twitching wire and plastic ties were used to reinforce the pneumatic chambers.
  • Re-install in reverse order and the system should be restored to fully operational.
  • A bonus was that an annoying rattle which had been present for years was discovered. It turned out to be the one way valve (black and white device in next picture) installed in the red pneumatic line to the trunk lid actuator. It was rattling against the boot lid and was fixed by securing firmly with plastic ties.

Acknowledgement

With thanks to BenzWorld Members dilsingh, deucer, OCKlasse and mercy-me. Downloadable pdfs are at reference Post #5: http://www.benzworld.org/forums/w220-s-class/1675592-w220-trunk-lid-hockey-puck-removal.html

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