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Lou P. master tech
Lou P. master tech, Mercedes Technician
Category: Mercedes
Satisfied Customers: 4834
Experience:  15 years master certified 100% fix rate and have access to factory radio codes, wiring, and instructions.
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S500: W220 2001 S500 will start and drive, but nothing works,

Customer Question

W220 2001 S500 will start and drive, but nothing works, turn sig., ac,.door loc., airmatic, and will not shut down when the key is removed. You have to remove the relay to shut it off. Then the brake lights stay on and the fan runs until you remove the battery cable.
Submitted: 2 years ago.
Category: Mercedes
Expert:  Lou P. master tech replied 2 years ago.
Hello my name is ***** ***** i will do my best to help you , i strive for EXCELLENT service and nothing less.did this happen after a recent rain ? Or car wash ?
Customer: replied 2 years ago.
no
Expert:  Lou P. master tech replied 2 years ago.
ok, what rekay are you removing? it sounds like the communications system or one of the front sam's have failed.
Customer: replied 2 years ago.
The starter relay
Expert:  Lou P. master tech replied 2 years ago.
what happened first? what sympton? was the car jump started? can you explain when and how this all happened, i need to get a feel for what is going on, this is not a common issue so it will take some thinking and diagnosis.
Customer: replied 2 years ago.
Just started it to drive to work and a big red battery image comes on in the display on the dash and tells take to work shop. Drove it to my body shop and it would not shut down until I removed the relay
Expert:  Lou P. master tech replied 2 years ago.
ok, great, so start the car and see what voltage the battery is charging at.
Customer: replied 2 years ago.
13v
Customer: replied 2 years ago.
I installed a new battery
Expert:  Lou P. master tech replied 2 years ago.
ok, did you just check it or are you going off of what you checked before? i need us to both be on the same page, and understand that when i ask of something it is definitely going to help with diagnosis, so heres what i need you to do, start the car and see if the warnings are consistent and the car contnues to run with the key turned off, then check the charging of the battery while its running, it has to be more than 13.0 but LESS than 14.8
Customer: replied 2 years ago.
I forgot to mention when you turn the key off to shut it down the key will not turn on until you disconnect the battery. It more than 13.0 but less than 14.
Expert:  Lou P. master tech replied 2 years ago.
ok , so this happens every-time the car runs?
Customer: replied 2 years ago.
Yes, but now the air has leaked from the air ride,so you cannot drive it.
Expert:  Lou P. master tech replied 2 years ago.
ok so is it position L that you are pulling the relay from?
Expert:  Lou P. master tech replied 2 years ago.
the link is the passenger side SAM, let me know where you are pulling the relay from, the starter relay is relay L and in the diagram if the relay was the issue the starter would continue to crank,
Customer: replied 2 years ago.
If X is toward the firewall the L is the one
Expert:  Lou P. master tech replied 2 years ago.
x is toward the front of the car
Expert:  Lou P. master tech replied 2 years ago.
and this is the fuse box on the passenger side of the cars engine bay
Customer: replied 2 years ago.
Yes that is the one that shuts it off
Expert:  Lou P. master tech replied 2 years ago.
ok, but to reiterate, the X is pointing towards the front of the car, not the firewall. we need to confirm on this
Expert:  Lou P. master tech replied 2 years ago.
if L is indeed the relay, then remove the relay and see if the car ignition turns on and off with no issues, it will not crank but at least we can see what happens.
Customer: replied 2 years ago.
Yes, that is the one, the layout of the box looked different, sorry
Expert:  Lou P. master tech replied 2 years ago.
heres the drivers side fuse box. just for reference
Expert:  Lou P. master tech replied 2 years ago.
arrows always point towards front of car
Customer: replied 2 years ago.
The key will not turn until you remove the battery ground and replace
Expert:  Lou P. master tech replied 2 years ago.
even with the relay removed?
Customer: replied 2 years ago.
yes
Expert:  Lou P. master tech replied 2 years ago.
remove the positive and negative cables and touch them together, it will drain all the control module capacitors, it may help, but just want to be sure, its called a global reset.
Customer: replied 2 years ago.
I have tried that
Customer: replied 2 years ago.
Everything leads to eis, but I still do not know why it will start and nothing else works
Expert:  Lou P. master tech replied 2 years ago.
yes i was going through the diagrams and you are on the right track , eis is the common denominator.
Expert:  Lou P. master tech replied 2 years ago.
eis is responsible for turning on the circuits to the control modules. so if have the car works then that is a very probable scenario
Customer: replied 2 years ago.
but normally the key will not turn in the ignition
Customer: replied 2 years ago.
could it be the ecu ?
Customer: replied 2 years ago.
or the ecm
Expert:  Lou P. master tech replied 2 years ago.
i agree most eis fails to where it wont turn, but the fact that the key will not be released tells me eis all the way. i dont see the engine module causing this and when you say ECM it is vague lol, as this car has 25 control modules all with specific names.
Expert:  Lou P. master tech replied 2 years ago.
i think we are on the same page, i vote EIS. hope this helps. the diagrams all point to eis. if you want to double check, start the car and in the passenger side fuse box, use a test light and tell me what fuses do NOT have power , that may help diagnose further, but the only thing that can affect the key not coming out or starting the car a second time, is the eis. hope this helps.Please take a second and click the box and rate my service GOOD OR EXCELLENT SERVICE if you feel I have been helpful and please request me in the future. If you feel I have not been helpful please DO NOT RATE BAD OR POOR AND WASTE YOUR MONEY , I will opt out to see if another expert can provide more or better assistance so you're not wasting your money!!. Thanks for choosing just answer. Lou. also , if you feel i deserve one , BONUSES are GREATLY APPRECIATED ! 😉Keep in mind that rating me does not end the chat, it simply credits me for assisting, i will still be here to help if follow up information is needed , Lou.
Customer: replied 2 years ago.
You can switch the key off and even remove it from the switch and it still runs
Expert:  Lou P. master tech replied 2 years ago.
ok then try this, pull fuse 78 in the passenger side DASH fuse box, its on the outside where the door meets the dash , start the car , shut the key off and remove it and then pull the fuse.
Customer: replied 2 years ago.
you can remove it and put it in your pocket and it still runs
Expert:  Lou P. master tech replied 2 years ago.
heres a pic
Customer: replied 2 years ago.
Is that the 7.5 fuse ?
Expert:  Lou P. master tech replied 2 years ago.
yes
Expert:  Lou P. master tech replied 2 years ago.
sorry my refresh on the computer is slow today for some reason