Pseudo Nim

So the tailgate on my R has been set to limit opening for the last however many years. It opens and closes correctly to that level. I have just disabled the limiter, and although the lid opens to the max, it will not close past that “halfway” point - it looks like it catches on that “halfway” limiter (while closing!), beeps, and goes back open. I can “help” it close and then I feel a resistance and once past that point it does close correctly, but looks like something is there.

Any advice on what to do with this? Do I need to disassemble the hatch?…

Tsumi

I had the same problem. What ended up working for me is doing a literal reset of the tailgate control unit using a clone STAR diagnostic system. I chose the options to install the tailgate control unit as a new unit, which ran it through a new calibration and that ended up working. A regular calibration from STAR diagnostic didn't work, and neither did flushing the hydraulic system. Flushing the system did clear out a lot of gunk though and I'm sure it made the tailgate perform better than it would have without it.

AFS2019

Hello, I have had this issue for years and had exchanged on a different thread but no one mentioned a full reset using the STAR diagnostic system or flushing the hydraulic system. Oddly, I was able to have the tailgate close properly when I removed all of the trimming attached to the tailgate (I was replacing the electric latch at the time). Are you referring to a flushing of just the hydraulic system tied to the tailgate or is this a total hydraulic flushing? I have seen the STAR diagnostic systems on Aliexpress but do you have the reference to the version that you used?

Tsumi

If this is your only issue, I would recommend trying to find someone around you that has a STAR system. Only get a STAR system if you plan to do other diagnostics with it. In my case, I was reprogramming my R500 to tow a trailer, the dash for an aftermarket headunit, and some troubleshooting with the headlights in addition to the tailgate issue. I actually wasn't planning on using it for the tailgate at all, I just had some spare time and decided to experiment around to see if I could get it working properly.

As for flushing, it was the liftgate hydraulic system only. The pump is located in the spare tire wheel well on the left side.

AFS2019

Got it. Thanks much. I am going to try a flush to see if that helps.

Pseudo Nim

This is great info. Thanks very much, this really helps. When you say STAR, you mean the Xentry DAS laptops they sell on Aliexpress, right? I do plan on getting one of those … can’t ever go wrong with a full diag suite. What was the procedure in it, is it relatively easy to figure out?

How did you flush the hydraulic system? What liquid goes in it etc?

Tsumi

I got the MB Star C4. In my case, since I'm relatively tech savvy, I just got the C4 control unit and set up Xentry on one of my spare laptops using Xentry downloads I was able to find.

The procedure was relatively easy for me to figure out, but I know from experience that when it comes to software, what is easy for me might as well be an alien language to others. I'll have to hook it up and see what menu options I used. Basically you just have to find the liftgate control module and find the option that says use for programming new unit or something along those lines.

As for the hydraulic fluid, I used Pentosin CHF11S fluid. I removed the rear spare tire hatch so I could sit inside the car while flushing. The procedures I used are as follows:
Remove pump from housing.
With liftgate closed, drain fluid from the plug on the reservoir.
Fill with new fluid to approximately the same level as before.
Put plug back on. While holding the pump flat, cycle the tailgate a few times.
Repeat drain, fill, and cycling tailgate until fluid drained is the color of the new fluid.

Pseudo Nim

Thanks. I used to code BMW with NCSExpert and INPA cables, I can’t fathom the Xentry interface being any worse or harder to set up. Were you able to find the cables cheaper? Cause I can only find kits with a hard disk or with a laptop - I wouldn’t mind saving the hardware costs as obv I have a laptop lying around.

Tsumi

Aliexpress listings change constantly. I bought my C4 about half a year ago, and the offerings now are different from what I remember them to be. I chose the highest quality unit (most expensive knockoff) that didn't include a hard drive or laptop.

Pseudo Nim

Understood. Thanks! Will give this a go

Pseudo Nim

Rereading this - what were you reprogramming on the dash for an aftermarket HU?

Tsumi

Disabling the clock being controlled by the head unit so I could set it manually in the dash menus. Probably going to be looking to disable navigation and compass next as they only work with the OEM nav unit.

Pseudo Nim

Ahh very cool. Yeah I’ll be doing the same. Which HU did you get? I’m hesitating because I don’t want to lose rear view camera functionality, but the standard HU is pretty abysmal… And I know I’m detailing my own thread. lol

Tsumi

I got one of the Android ones. My R500 didn't come with a backup camera, so I installed an OEM-style one on my own. You should be able to get adapters to make it work with whatever aftermarket unit you get. You'll be looking for a Fakra to RCA adapter.

If you're ever looking for additional info, try looking in the X164 and W164 forums. Electronically they are identical to our cars.

Pseudo Nim

Awesome. Thanks. Wasn’t sure if the OEM one can be adapted. That’s good info - appreciate it!

Pseudo Nim

To flush the system, did you need to go through the complete WIS procedure of removing the headliner, paneling, etc, or is most of the pump reachable by just opening the left hatch? I'm just reading the procedure now, trying to filter what's mandatory from what just makes life easier.

Tsumi

Nope, the pump is contained in the black box on the left side of the spare tire wheel well and is fully accessible. I suppose if you didn't want to have to cycle the system, you would go through the procedure of removing the panels. I figured about 10 cycles was more than sufficient to replace most of the old fluid with the new fluid, and it doesn't use that much fluid anyways. I've done something like 20 flushes and barely used half a liter.

Pseudo Nim

Nah, I don't mind cycling it. Though, I think I need Star to cycle it, based on your message below, right? If so, that's still on the list of things to get for the car, so I'll probably wait a bit. I have VW power steering fluid I bought for a leaking RS6 steering rack that I then sold, so that hopefully will be compatible, haha.

Tsumi

I didn't use the STAR system, I had the liftgate open and close a bunch of times while sitting in the trunk. Removing the spare tire hatch is necessary to work it from the inside, and the lines are a little short so the position will be a bit awkward. You'll see when you take everything apart.

Pseudo Nim

Ok, so I opened the area up and this seems to be the pump. Would you mind sharing what you unplugged / what you did so I don't do anything stupid? I tried to find the procedure in WIS, but not unexpectedly, it's not really there. I think the screw with the blue head in the centre is the pressure release valve, right? What do you unscrew to empty the lines from the hydraulic fluid, and where do you inject it back? Do you need any special equipment for it? (syringes etc) Would regular power steering fluid work? I feel like I should unscrew one of the hydraulic lines on the left and close the hatch. That should leak all the fluid out, then attach it back, undo the blue headed bolt, and use some sort of a funnel to feed fluid back in, then open it so the lines get filled, and keep adding fluid. I think. Does that make sense? Thanks for your help!

Tsumi

Pull the entire pump out of there while leaving all the hoses and wiring intact. At the top of the plastic reservoir (seen on the left in your picture), there is a cap screw for draining/filling.