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Lou P. master tech
Lou P. master tech, Mercedes Technician
Category: Mercedes
Satisfied Customers: 4148
Experience:  15 years master certified 100% fix rate and have access to factory radio codes, wiring, and instructions.
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Got a 2007 s550 i changed the rear battrey and now it will

Customer Question

got a 2007 s550 i changed the rear battrey and now it will not start or turn over
JA: Have you changed a battery before?
Customer: yes
JA: Are you fixing your S550 yourself? What have you tried so far?
Customer: changed the key fob batteries and tried to start with the key fob, checking fuses now
JA: Anything else you want the mechanic to know before I connect you?
Customer: no
Submitted: 8 months ago.
Category: Mercedes
Expert:  Lou P. master tech replied 8 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,keep in mind that since we are doing this over the internet i need as much info as possible about your issue no matter what seems important or not, all info is helpful. Also please do not simply rate negative if you find an issue with info that is relayed, i am truly here to help and will do what i can to get you the information you need,thanks!

Customer: replied 8 months ago.
Thank you I change the battery out of the rear I followed all the procedures turned everything off in the car got no spikes to it now the car will not turn over I have lights on the dash but it will not turn over start
Expert:  Lou P. master tech replied 8 months ago.

ok so what is the voltage of the new battery, are the cables tight where they cannot be twisted?

Customer: replied 8 months ago.
12.3. And tight
Expert:  Lou P. master tech replied 8 months ago.

ok next question, what is the voltage of the front battery and are the cables tight?

Customer: replied 8 months ago.
I believe we have a security lock out issues what is happened or maybe a fuse but I'll check the front battery also
Expert:  Lou P. master tech replied 8 months ago.

security issues are bypassed once the key is inserted into the ignition.

Customer: replied 8 months ago.
Front battery voltage is 12.3 to it almost seems like the starters been disengaged
Expert:  Lou P. master tech replied 8 months ago.

ok so close the doors, lock and unlock the car, then see if it will crank.

Customer: replied 8 months ago.
I closed all the doors and with the key fog in my hand it will not lock the car
Expert:  Lou P. master tech replied 8 months ago.

ok good, so now turn the key on, and use your meter and tell me what fuses do NOT HAVE BATTERY VOLTAGE in the front fuse box and the rear fuse box in the armrest area . its between the center of the seats.

again, i need to know what fuses do not have power. if you find a blown one good , but i am concerned with power supply, so please do not confuse the two. let me know the numbers of fuses with no power and i will back trace the circuit.

Customer: replied 8 months ago.
The remote will not even open the trunk and I have changed fresh batteries out into the remote
Expert:  Lou P. master tech replied 8 months ago.

the rear sam (fuse box) is what the locking signal goes through, but i want you to check for power in both front and rear fuse boxes. i think a major fuse blew inside the power module located above the battery in the trunk.

Customer: replied 8 months ago.
We are pulling the panel to get to the roof use box now will be back shortly
Expert:  Lou P. master tech replied 8 months ago.

OK. just so you know the rear fuse box is inside the hole for the rear center console, there is a removable floor that pops up.

Expert:  Lou P. master tech replied 8 months ago.

i just created a huge file with all the fuse box info, if you would like it to have i am sending over a email exchange offer so i can email it to you.

Customer: replied 8 months ago.
They are still checking the fuses but the doorlock to work with the remote I was wrong on that
Expert:  Lou P. master tech replied 8 months ago.

ok so then the door locks work?

either way we still need to check all the fuses for power. thanks

Customer: replied 8 months ago.
All the fuses in the rear portion of the car we're good
Expert:  Lou P. master tech replied 8 months ago.

Ok but did they have battery power ??????????

Also what about the front fuse box

Customer: replied 8 months ago.
Currently everything have power with check the front it all appears to have power on the dash it says do not recognize key
Expert:  Lou P. master tech replied 8 months ago.

Oh it does !? Has it said this the whole time !? Is this a push button start ?

Customer: replied 8 months ago.
it is a pushbutton and I have remove the button and inserted the key and try to start it that way the car doesn't even turn over , someone else told me maybe I should disconnect the battery totally and touch the cables together to try and clear all signals to the car is this true never heard of it
Expert:  Lou P. master tech replied 8 months ago.

Yes that is true. It's called a global reset. That would actually be my next step. Remove the button and insert the key. If no go then go do the reset. What it does is clears all the voltage from all the modules. BUT since you have 2 batteries you need to do this with both of them. So remove the negative and then the positive of both and do this. It only takes a few seconds when you hold them together.

Customer: replied 8 months ago.
Already well I'll try that first thing in the morning and get back to you thank you
Expert:  Lou P. master tech replied 8 months ago.

Ok no problem. Sorry this is taking so long. It's an odd issue that the global reset may actually fix lol. Also if you have a scan tool codes will obviously help.

Customer: replied 8 months ago.
I have a scan tool and I don't really have any codes at all I will try that first thing in the morning thank you how long should I hold the cables together
Expert:  Lou P. master tech replied 8 months ago.

like i said only a few seconds, so like just count to 10 and that would be fine .

Customer: replied 8 months ago.
Well we did the global reset this morning and it did not work same issue
Expert:  Lou P. master tech replied 8 months ago.

ok... i am here. thinking.

Expert:  Lou P. master tech replied 8 months ago.

ok so do you see the big module above the rear battery that the power wire goes into?

Expert:  Lou P. master tech replied 8 months ago.

we need to verify voltage coming out of all red wires on this module.

Customer: replied 8 months ago.
The car now starts the front battery appeared to be low but it will not shift it says intelligent solenoid not engaging it will not shift at all
Expert:  Lou P. master tech replied 8 months ago.

ok, i thought we went over the battery, you stated voltage was good before..........

i say either replace or recharge the battery and then see if the warning is still there. if so you need a scan tool to diagnose the ISM, it does not make sense to try and go further without having proper voltage.

I have taken my time to answer your question the best i could and i will continue to help if you need follow up information , all i ask is that you PLEASE take a second to rate my service so i may receive my credit for assisting you. Thank you.

Expert:  Lou P. master tech replied 8 months ago.

I have taken my time to answer your question the best i could and i will continue to help if you need follow up information , all i ask is that you PLEASE take a second to rate my service so i may receive my credit for assisting you. Thank you.