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Ask Lou P. master tech Your Own Question
Lou P. master tech
Lou P. master tech, Mercedes Technician
Category: Mercedes
Satisfied Customers: 4805
Experience:  15 years master certified 100% fix rate and have access to factory radio codes, wiring, and instructions.
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The lock and unlock button and the drivers door and the

Customer Question

The lock and unlock button and the drivers door and the passenger door does not work. The locks work with the remote control and it unlocks when I open the drivers door, but the button doesn't workAttn Lou
Submitted: 11 months ago.
Category: Mercedes
Customer: replied 11 months ago.
The rear window button doesn't work, the windows goes up and down but only from the drivers command it doesn't work from the doors command. They do work with the key too.
Attn Lou P
Expert:  Lou P. master tech replied 11 months ago.

Hello, my name is***** and i will do my best to assist you.I am going over your story now and will reply back soon with some info,thanks!

Expert:  Lou P. master tech replied 11 months ago.

im pulling up the diagram now. i think we are dealing with another relay issue, but let me check the diagrams.

Expert:  Lou P. master tech replied 11 months ago.

ok these have to be 2 diff issues, so first make sure the child lock is not set on the drivers window switch assembly. its the long bar at the bottom of the switch, that will stop the rear windows from working from the rear switches. as for the front lock switches, each switch goes to an individual module on the doors, so it cant be the switches......

Customer: replied 11 months ago.
I'm sure that the safe lock is not active
Customer: replied 11 months ago.
How can I test the switches? I know that they are powered because they are lighting up.
Expert:  Lou P. master tech replied 11 months ago.

ok, so even if the safe lock appears to be off the switch can be defective and not be releasing the child lock, check to see if the rear power outlet works as well, i think the child lock will kill power to the power outlets as well.

Customer: replied 11 months ago.
I Willoughby's
Customer: replied 11 months ago.
I will
Expert:  Lou P. master tech replied 11 months ago.

in the diagram it tells me no test info available for the lock switches, i can see that the power window switch and the door lock switch share the same power input, and that power input also powers the led. the ground is shared by the entry lamps on the doors so if the lights come on then the ground is ok. did this happen after the battery disconnect issue ? or was this an issue before hand?

Customer: replied 11 months ago.
Before. That's why I disconnected the batttery. To reset the module and see if they work
Customer: replied 11 months ago.
The entry lamps are working fine
Customer: replied 11 months ago.
Oh, there is another issues , maybe they are related.
Customer: replied 11 months ago.
On the driver side the front and rear door handle sensor is not working. The one that unlocks the door when you touch the handle, and the locking button in the handle too. but only the left side doesn't work the right side does.
Customer: replied 11 months ago.
With the scaner it says left rear door antena short circuit
Customer: replied 11 months ago.
I bought an antenna and replaced but nothing changed.
Expert:  Lou P. master tech replied 11 months ago.

hold the phone, you have a icarsoft right? or what scanner are you using/

Customer: replied 11 months ago.
Icarsoft
Expert:  Lou P. master tech replied 11 months ago.

ok so the car has keyless go as well, that can affect it. ok can you access the door control unit with the scanner?

Customer: replied 11 months ago.
If guide me, yes.
Customer: replied 11 months ago.
But I can't do it not
Customer: replied 11 months ago.
Only 3 hours from now
Customer: replied 11 months ago.
I never access the door control unit with it, I went to the keyless go module
Expert:  Lou P. master tech replied 11 months ago.

what do you mean 3 hours from now?

Customer: replied 11 months ago.
Customer: replied 11 months ago.
Will you still be available?
Expert:  Lou P. master tech replied 11 months ago.

sorry , my work gets busy at this time, and then i have to commute. so we can continue later if that is best.

Customer: replied 11 months ago.
What time?
Expert:  Lou P. master tech replied 11 months ago.

what time is it by you right now?

Expert:  Lou P. master tech replied 11 months ago.

would probably be near 6-7 pm central time. right now its 233 by me

Customer: replied 11 months ago.
Ok, we talk later
Customer: replied 11 months ago.
Are you there?
Customer: replied 11 months ago.
Expert:  Lou P. master tech replied 11 months ago.

here yes

Customer: replied 11 months ago.
Ok, what do you want me to do?
Customer: replied 11 months ago.
I'm with the scanner
Expert:  Lou P. master tech replied 11 months ago.

ok, i have not worked with one of these before so lets take it screen by screen.

Expert:  Lou P. master tech replied 11 months ago.

when you pick the car , can you see a list of modules that you can pick?

Customer: replied 11 months ago.
Ok
Expert:  Lou P. master tech replied 11 months ago.

we need to see if there are door control modules we can see,. or sam modules.

Customer: replied 11 months ago.
I'm on it
Customer: replied 11 months ago.
Tested the child lock, it is working normally
Customer: replied 11 months ago.
I have access to the right front door and to the left front door from the scanner but I don't have access to the rear doors
Expert:  Lou P. master tech replied 11 months ago.

ok there is no rear door modules on these i dont think, the front sam does the windows. let me recheck

Expert:  Lou P. master tech replied 11 months ago.

ok so we need to see if we can access the left front door control module and if we can see a signal for the lock switch

Customer: replied 11 months ago.
I can
Expert:  Lou P. master tech replied 11 months ago.

ok so does it show if the switch is being activated?

Customer: replied 11 months ago.
But yes, but nothing changes when I activate the switch
Expert:  Lou P. master tech replied 11 months ago.

ok so to be on the same page, the scanner shows the value but when pressing the switch the value does not change? if this is the case then check the right front door control module.

Customer: replied 11 months ago.
Same thing
Expert:  Lou P. master tech replied 11 months ago.

OK, so here is how you remove the switches,

Customer: replied 11 months ago.
Then what
Expert:  Lou P. master tech replied 11 months ago.

use 2 fingers, press the lock and unlock at the same time, and then use your fingernail to pull the plastic slider out of the middle of the switch, it will slide out a little bit to release the switch.

Expert:  Lou P. master tech replied 11 months ago.

lets just get them unplugged and see if plugging them back in works or not,

Customer: replied 11 months ago.
Doesn't work
Expert:  Lou P. master tech replied 11 months ago.

did you get the switch out?

Customer: replied 11 months ago.
Expert:  Lou P. master tech replied 11 months ago.

ok making sure.

im trying to think of the best route of diagnosis with least amount of work and teardown.

Expert:  Lou P. master tech replied 11 months ago.

OK so did both lock switches stop working at the same time? or have you not noticed if the passenger one ever worked?

Expert:  Lou P. master tech replied 11 months ago.

so both switches go into the individual door modules and then the modules lock the latches and also send the signal to unlock the rear latches. so its hard to say that you have 2 switches that failed. BUT it is looking so. if you unplug the switch was there a fault code in the door control module?

Customer: replied 11 months ago.
My wife left with the car I'll need to check that later
Customer: replied 11 months ago.
what's next?
Customer: replied 11 months ago.
Let's save that it doesn't show fault
Expert:  Lou P. master tech replied 11 months ago.

if it doesnt show a fault with the switch unplugged then we have a issue with the door module, if we unplug the switch the door module should show a fault for open circuit. that is what i want to see, if we see that , then that means we can have a faulty switch.

Customer: replied 11 months ago.
Ok, I'll check and let you know
Expert:  Lou P. master tech replied 11 months ago.

OK

Customer: replied 11 months ago.
I disconnected the switch, no fault
Expert:  Lou P. master tech replied 11 months ago.

That is odd. Like really odd. I would like to think that the door module would have thrown a code. At this point I don't know if it's a scanner issue for not seeing a fault code or a car issue for not throwing a fault code.

Customer: replied 11 months ago.
What about the door handle sensor?
Customer: replied 11 months ago.
How can I fix it?
Expert:  Lou P. master tech replied 11 months ago.

ok, this issue has me really confused, there is something missing.

for the door handle, can you see actual values in the keyless go module?

the handles on these models are very problematic, they cause issues sometimes, the lock and unlock feature both fail , not always together. the only way to fix is to replace the handle. they are super easy to change.

as for the inner door lock switch, i keep going over the scenario and the only thing that would make sense is if both lock switches failed. but that is so uncommon.

Customer: replied 11 months ago.
Do you have a diy to switch the handle?
Expert:  Lou P. master tech replied 11 months ago.

yeah i can get you that, it will be a little later tonight, i am about to leave work. that is why i always disappear this time of day, lol, gotta get kids from daycare and get them settled then i get back online. ill get you the info, send me another message so i see you in the request center.

Expert:  Lou P. master tech replied 11 months ago.

here you go man.