CarolinaR320

I have a 2007 R320 with an automatic lift gate. It almost closes by itself until 2/3 of the way down then needs a light "assist" or it goes back all the way up. It opens all the way fine although I've noticed that it doesn't like to stay open below 50 degree F.

Looking for ideas to solve this issue. I found a schematic that shows a hydraulic pump. It may need fluid as this seems to be an issue with the ML/GL units. What type of fluid is used in this tail gate lift system?

Thank you.

Plutoe

your girlfriend cant fix this one---find someone with DAS Xentry diagnostics to make adjustments or live with it

Tsumi

I'll have to look up what I used, but I can tell you from experience that simply filling up the pump will not fix your issues. I have bought a replacement pump and plan to replace it in the coming weeks- hopefully that will solve the issue.

CarolinaR320

Well, I refilled the reservoir this weekend and that did not fix my issue. Sounds like the driver's side roof top actuator is the issue. It does open/close better with more fluid but I still have to "hand assist" the tailgate about 2/3 of the way to close. Not really a big deal if it will now consistently stay open by itself which was my other issue.

twhumphrey

After having this problem for several years and already investigating the hydraulic system as the OP did, I consulted with a Mercedes expert, who told me that this problem comes from the sensor that detects that the lift gate is fully closed. That sensor is in the D pillar and ja subject to failure if water is able to ingress into the car and flow down the D Pillar. There are water plugs at the top of the lift gate opening that must be well sealed to prevent water ingress, which will cause this problem as well as other electronic problems in the floor of the tailgate area (where the Keyless-GO module happens to be mounted). If the sensor has failed, it does not detect that the liftgate is closing, then the liftgate will reverse when nearly closed, and reopen. I am going to replace the sensor in my car and see if it fixes this problem….

CarolinaR320

Please let us know how replacing the sensor works for you.

CarolinaR320

Did replacing the D pillar sensor fix the closing issue for you?

Tsumi

I bypassed the sensors with the resistor method, did not fix my problem. The sensor fix only works when the problem is that it will only close a little bit and then reverse. If it's closing at least 1/4 of the way before reversing, the problem lays elsewhere.

CarolinaR320

OK. Thank you for the update. My tailgate works well enough. All it needs is a little "help" about 3/4 way down and then finishes/latches securely. Not bad all things considered for a nearly 18 year old SUV with 195k miles.