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Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53940
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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Pearl, JA: Sometimes things that you think will be really

Customer Question

Hi Pearl,
JA: Sometimes things that you think will be really complicated end up being easy to fix with a Mercedes. The Mercedes Mechanic I'm going to connect you with knows all the tricks and shortcuts. Tell me a bit more about what's going on so he can help you best.
Customer: Yes I have a 2002 S430. I kept blowing fuses in the pneumatic pump so I replaced the motor. All functions now work except the trunk. I can automatically close the trunk but not open it. When I use the key fob or the door control the lock releases but the trunk won't rise. Feels like something is oput of sync? any ideas?
JA: Dealing with a malfunctioning key fob can be frustrating and really inconvenient -- the mechanics will have somegood ideas about what to do. Are you hoping to fix this yourself?
Customer: yES
JA: Great! What have you tried so far?
Customer: Originally none of the functions worked until I replaced the electric motor inside the pump. Now it all works but trunk opening I also tried resetting by removing the fuse as I've seen on other post.
JA: Is there anything else the Mercedes Mechanic should be aware of about your Mercedes?
Customer: No otherwise
runs well
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Mercedes Mechanic about your situation and then connect you two.
Submitted: 1 year ago.
Category: Mercedes
Expert:  Marty replied 1 year ago.
Hi, welcome to Just Answer. My name is***** you please post the last 8 digits of your vin number?
Customer: replied 1 year ago.
Expert:  Marty replied 1 year ago.
I need the last 8 digits.
Customer: replied 1 year ago.
Customer: replied 1 year ago.
Just chat thank you
Expert:  Marty replied 1 year ago.
Okay, the power opening and closing trunk lid is not part of the function of the PSE module. The trunk lid is operated by the hydraulic pump in the trunk. Fuse 57 in the rear fuse box is for the pump. Inspect the fuse and remove and reinsert it and see if the trunk raises when you release it. Let me know what you find.
Expert:  Marty replied 1 year ago.
Click on the attachment for the location of fuse 57 in the rear fuse box.
Customer: replied 1 year ago.
Thanks Marty,fuse looks fine. plugged it back in still no luck
Expert:  Marty replied 1 year ago.
The next step will be to get the car connected to the Mercedes tester to initialize the power closing trunk. You can try raising the trunk fully by hand and then press the button to close the trunk and see if it will pull it closed. If you have no success you will need to run the initialization procedure with the Mercedes tester. All this is assuming that the hydraulic pump is good.
Customer: replied 1 year ago.
Closing function works normal
Expert:  Marty replied 1 year ago.
The initialization may still fix the problem or there may be a fault with the position sensor for the trunk lid. They will need to run diagnostics to check for fault codes. The sensor is located on the right side ram for the trunk lid. I've attached a picture below.