new550

Need some expertise... I believe my trunk release module is bad (relay inside not holding). Two questions:


1) If I replace with used one from eBay etch., will I have to still get it programmed to my VIN # ?


2) EPC shows my part A2218706185 is replaced by A22187006387 ... if I replace mine with a used, but updated part number, is that better or does it create other issues?


Thanks for any help understanding this situation...I just can't do $500 part plus labor from dealer for what I hope is a quick part swap...


2007 S5504matic

greglig

Hi I did some digging in the Mercedes Star scanner (in simulation mode) there does not apear to be any vin stored.

On later cars 08-> the vin is stored as I can see.

The only problem you will have is the trunk lid position will need to re-learned (normalization). Otherwise it may not work at all or go part way up or down.

It may actually be your trunk position sensor that is the problem and not the module.

Can you give us more details of the fault?

new550

You might be right on the sensor as problem. When pushing open button on trunk or drivers door, the trunk will only move part way open or close.... not same spot each time....I disconnected the pump itself and the relay briefly picks up, but does not stay engaged. This makes me think its not the pump or actuator itself, since the symptom is present when its disconnected.


Problem can be worked around by pushing the button 3 or 4 times, which will move it to closed or open, but never in one push as normal.


I took the module out and applied 12 v across the relay coils on the circuit board itself, and it stayed engaged, so that got me thinking about the position sensor vs module, but don't know how to test that...I figured the relay would be the weak link on the module itself....


Thanks for research, any ideas on next steps?

greglig

Hi, very good we are getting somewhere. Easy to test if you have a multimeter and a helper.
I have attached a circuit diagram of the system.
You will need to backprobe the module and check the voltage coming from the sensor. By backprobe what I mean is to carefully make contact with the pin in the back of the connector while the module is still connected and powered up.
You can measure just the signal wire at the module and connect the multimeter ground to the body or battery negative.
Next you will probably need to get into the trunk and get a helper to move the trunk lid to it's extremities. Maby do it quickly and then slowly.
What your looking for firstly if it is doing anything at all or if it's working then smoothness in the signal (no sudden jumps etc). This may be hard if you have a cheap meter as they will probably not be fast enough to pick up that sort of thing. I would normally use a scope to look at that type of signal to pickup on noise.

If all seems ok it maby that you need to have error codes read and possibly the trunk normalized.

new550

Thanks, will be a couple days before I can check.... will, let you know...

greglig

One other thing that I just remembered. Weak struts can also cause a similar problem as control module senses too much load and stops lifting (ie the system thinks someone or something is on the trunk lid). This much like the anti-pinch feature of the power windows.

I had the same thing on a 7 series a number of years ago.

Cheers.

new550

I'll check that as well.... need the rain to stop.... will keep posted

new550

OK....got to work on it this pm.....
I am reading a full 5.01vDC across the common to power on the position sensor wiring and range from 1.41 vDC to 3.49 vDC closed to open on the trunk lid. Seems pretty steady and is repeatable, so that seems to be working correctly (?)


I removed the strut and it appears to move freely or at least as I expect with the resistance its there for...no binding or hard effort required to move.


With the pump power disconnected, the deck lid seems a bit hard to open once closed and allowed to sit, then opened again....assuming that is the hydraulic fluid moving from one side to the other within the cylinder, but not sure what the normal mode is for that part of this.... any ideas or additional checks for me to make?

greglig

Hi, I concur with you and think the reading seem normal. Strut tension may be a little hard to judge as new struts are usually very stiff and hard to collapse by hand. You may need a second opinion on the that, are there any mobile strut re-gas companies you could talk to? Not sure if you have them in the States but we had them in Australia.

Ok, one other really silly thing look at the pump and see if it's low on hydraulic fluid. If it is I would have to check what type to use as you cannot use just anything.

If all else fails it may need the Star Scanner to check what's going on error codes and re-learn.

greglig

Hi new550, Just a quick question as you have the same era car as me.


What are your headlights like? I had old worn out bulbs in mine and have just replaced them with Osram Xenon Night Breaker Ulimited's which has made a marked improvement in low beam but high beam is somewhat poor. Low beams could also be better.

Cheers.

greglig

Sorry, error!! Please ignore what I said about the strut. Just had a look though parts catalog and service info, I was under the impression that there was the hydraulic ram on one side and a normal gas strut on the other which helped lift the trunk lid (as it's done on other vehicles).
I did not realize there was a huge counter balance spring and only the ram.

More thoughts:
On the older W220 you can do normalization reset by following a sequence without needing a scan tool.

Now this is a total guess but based on the older sequence and may work as.

- Switch the ignition to second position (engine not running) - Or you could also try position 1.

- Make sure trunk is closed

- Press and hold trunk switch on drivers door until it fully opens and keep it pressed down for at least 5 - 10 seconds after the trunk open fully (if it decides to open).

- If it does not open (or only partially), press it again utill it closes and keep the button pressed for a least 5 - 10 seconds after it latches.

- Press and hold the trunk button down and keep holding it for 5 - 10 seconds after the trunk fully opens.

Here is a link to a video for the W220:


From about 6:25 he goes through the procedure.
The video is not mine I just found a random one on youtube.

Cheers.

new550

Will try it.... just replaced low beams with Philips D1S Xenon HID (I have bi-xenon option) they seem good, but were ok before flickering.... high beams are still original and are still good....

greglig

Hi new550, thanks for the info. I think my reflectors are burn and/or hazed.

Cheers.

new550

no luck on reset procedure, guess I will have to see the dealer.... bummer

greglig

Hi, sorry best I can do.

Cheers.