GregT94

Just bought this car from a buddy who hooked up the battery terminals backwards trying to get it going again.

back story car was running fine he took it home one day and parked it came out to a dead battery, jumped the car and it worked did this a few times until it just wouldn’t start. He put a new battery in and reversed the terminals now the car has no power and won’t start. Wondering what fuses I may need to replace or other damage that could have been done?
Any help in the diagnosis process would be greatly appreciated, I’m not familiar at all with these cars

GregT94

Any advice?

Edward Lowdell

I had this problem when I first bought my 55, the previous owner had done the same thing. Mine was stick in limp mode however. If you have nothing at all I hate to say but he might have fried the ECU. Bet have it looked at.

Agent-A01

Check fuses, most likely popped the main 'big' fuses that are located under the passenger footwell on a lot of mercedes.

GregT94

You think even having power to the dash windows and radio working it could be one of those big main fuses?

im fearing that about the ecu just hopeful it could be something as simple as a fuse

GregT94

The car won’t start no crank back windows don’t work all dash lights are functional radio works interior lights work the windows in the rear won’t seal up or come up or down but the fronts work fine as well as the sun roof

insame1

you are going to need to do some troubleshooting and reply back with what you did and the results if you want any more help.

GregT94

I checked the fuses inside the positive jump terminal I checks the window fuses and fuses under the hood related to ecm (the ones on the driver side)
I’m not sure where else to start looking is there a way to test the ecm? Could it be battery related I haven’t had the battery load tested yet

GregT94

Is there a way to diy test it before taking it to the dealer?

GregT94

I’ll give them a look when I get home in a few minutes, you think even having power to the car it could be a big main fuse?

GregT94

Okay update on the car I replaced the battery still nothing, then I pulled the ecu and it had corrosion on it so I cleaned it with 99% alcohol and a toothbrush let it dry and re installed, car is now running and driving under its own power but throwing fault codes
P0103
P0221
P203A
p20D4
P203B
P2004