MB-Dude

Unusual problem has developed - the trunk lid does not open all the way to the extreme limit (say, short by a few degrees) and when the trunk lid closes it slams (and I mean *slams*) hard onto the latch. Already checked for the infamous trunk lid travel limit, and it's set 'Off'. The trunk lid action acts as if the overall limits have shifted downwards a few degrees. Not opening far enough before the pump stops, and does not stop just short of the latch but continues to drive the lid hard into the latch. Soft-close doesn't even get a chance to activate; the lid slams shut. Any thoughts on what could change the travel limits? Lid drive cylinder appears to be stable and not loose. Sensor? Thanks in advance.
Cheers,
Jeff

ibeforreal

Jeff,
Two things.
First, to fix the limiter you can start the car or put the key in position (2). Now hold down the button on the driver's door that opens the trunk. Hold the button toward the front of the car for about 10 seconds. That should reset the limiter.

Second, if your trunk is slamming down you probably need to replace the struts. You can buy them both for less than $100 dollars and they take about 5 minutes each to replace. You can buy them from one of the sponsors on this forum. http://www.pelicanparts.com, or http://www.ecstuning.com. Any of their prices will certainly beat the dealer. They will most likely be listed under body parts. Do a search for Trunk Struts, or Trunk Shocks.

MB-Dude

Thanks John for the tips. Unfortunately, I had already tried the 10-second rule procedure with no success. And I changed the struts (with MB OEM parts) to cure the infamous trunk lid guillotine syndrome. No, this problem seems like something has shifted or changed in reference to how the trunk lid opens and closes. It's like the hydraulic cylinder has shifted or moved. Nevertheless, thanks again.
Cheers,
Jeff

ibeforreal

Have you checked the pump in the trunk to make sure it has fluid in it. The one that sits next to the battery under the foam padding? Make sure it has fluid. If it doesn't, use the Pentosin CHF11 to refill. This is the stuff in the green container.

MB-Dude

Worked on this problem again today. Checked the pump (thanks for the thought, John) and the reservoir is full. Also reverified the overall installation of the drive cylinder, sensor rod and sensor. All seems in order. I did find an adaption procedure in DAS, which is to 'normalize' the trunk movement. The DAS subroutine is simple but had little effect and no errors were reported. Even repeated it a couple of times. Removed the angle sensor and ensured there was no binding or other abnormality. I even played with a few of the DAS adaptations to see if I could make a change -any change- in the operation. This is a strange problem, indeed. Trunk opens, stopping short of full extend (however the new struts push the trunk open fully). But when closing, the trunk lid slams hard onto the latch. In my mind, I remember the trunk closing rapidly, stopping just short of full closure and 'soft close' takes it the rest of the way. Now, the lid slams as if Magilla Gorilla is closing the lid. Does the trunk latch mechanism sense the eyelet and stop the hydraulic pump so that soft close can gently finish the closure?

The trunk lid is controlled through the PSE circuit, even though the PSE is used only for soft close. Is it possible the PSE pump module (and associated electronics) has an error? DAS is reporting timeout errors for door locking even though the doors lock acceptably.

Cheers,
Jeff

wallyp

Grasping at straws - Is it possible that the trunk soft-close has failed, and the closer is compensating for that? Quick, easy and free - try pulling the yellow 20-Amp fuse to reset the PSE system, and see if the closing operation changes.

MB-Dude

Thanks Wally for the idea. However, pulling fuse #62 (yellow 20A) made no difference. It did however send me down a troubleshooting path. Indeed, pulling the fuse disables the PSE... which disabled ALL trunk open/close functions. So, hauling out the ohmmeter, I found the trunk angle sensor has 3 wires that go directly to the PSE unit; pins 1,5,7 (brown, brown/green, red/green, respectively). Pin 5 connects to the wiper of the angle sensor. Activating the angle sensor registers at the PSE plug with a range of 1.1Kohms to 5.4Kohms, end-to-end activation. So the angle sensor 'seems' OK. The PSE unit receives angular information from the sensor and thus controls the trunk lid hydraulic pump. So if the angle sensor appears OK, the PSE is now under suspicion.


In addition to the trunk lid slamming issue, XENTRY/DAS reports all four doors have a lock activation timeout error... even though they all lock in what I think is a pretty quick time frame (1-2 seconds). And through today's the troubleshooting activities, the trunk lid external activation button no long works. What does it connect to? Yup, the PSE. I'm beginning to believe the PSE electronics (inside the casing) has/is going bad creating a number of errors. But replacement is an expensive proposition on an educated guess. So, any more thoughts from the studio audience? Thanks in advance.


Cheers,
Jeff

ibeforreal

Before spending anymore time and money disconnect the battery for about 1/2 hour. Once you reconnect and go through they synchronization process, e.g., windows, sunroof top, wheels lock to lock, TCU, etc., see if that reset all of the issues raised with pulling the fuse.

MB-Dude

I assume when you talk about resetting the TCU, you are talking about the key-to-position-2-hold-down-throttle-for-10-seconds routine. Or is there another TCU resetting procedure?
Cheers,
Jeff

ibeforreal

That is the one.

MB-Dude

Great thought John, but it only cured the external open button functionality. The trunk slamming issue remains unchanged. And I am noticing the trunk hydraulic pump is remaining activated for up to 5 seconds after the trunk lid slams shut. However, I also sense the soft close activating, even though the lid is fully closed. Everything points to the PSE, yet I remain a bit doubtful.
Cheers,
Jeff

ibeforreal

Could very possibly be a leak in the vacuum line that runs to the trunk lock actuator or the actuator itself.