Kevinram123

Hey guys my trunk won’t open from using the key fob or the button inside the car and if u press the handle on trunk it won’t open also. If I take the key out from the fob and try to open it, it’ll open that way only. Anyone have any idea what the problems is and how to fix it? Thank uuuu

Shadly1

You have a Trunk Lid Release Module that probably went sideways. When you do manually open your trunk, do you have any lights inside or on the lid close buttons? That's a dead giveaway. Scan your car with MB Diagnostics stuff and you'll be able to tell what's wrong.

chassis

For sale of completeness also replace the fob batteries. It does sound like a model went dead. W204 or W203 seems to have old age trunk opening problems, try searching.

Kevinram123

Hey guys I’m back so here’s a an update on it, the lights on the buttons on the lid to lock the trunk and close it all have lights on them and now the button inside the car is working back but only the key fob isn’t working. Any ideas. And when I click the close button on the trunk lid it closes normally

w126w221

I believe there is a valet lockout for remote opening via the key. Check your owner's manual pg. 94 - 96. If you don't have an owners manual Mercedes still offers free PDFs at: https://www.mbusa.com/en/owners/manuals

If all your functionality works from the interior trunk button, trunk close and lock buttons on the trunk lid, and the exterior rear trunk release switch, then you need to start looking into the central lock (CL) system. I recently had to review the entire electrical system for the trunk because I had an issue where the lights sometimes would, and sometimes wouldn't illuminate following opening the trunk. What I found was the following.

For trunk opening and closing, you have four main modules with communication between them:

1. Trunk Power Close/Open Module (TPCOM) (My acronym)
2. Rear Signal Acquisition Module (RSAM)
3. CL Module
4. Infotainment Module

The TPCOM controls: the opening/closing of the trunk, monitoring the trunk latch motor, exterior opening switch, trunk lid close/lock buttons, and inclination and angle sensors. The RSAM is the main interface between the interior trunk lid button, CL module and thus key requests/activations, infotainment setting of height restriction, and finally a couple of microswitches within the rear trunk latch for trunk illumination (likely where my issue resides as I have zero errors for the RSAM).

The is a very generalized summary, and at this point in your work it is time to acquire an Xentry system scan to read the modules and faults. If you want I can export all the functions and wiring diagrams for the trunk for your review, just will take a couple of days!