battery connected wrong

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So, it does look like a fried ECU. That's not looking good (for the wallet) :eek:
 
As a long shot........contact your insurance company and ask them if the 'accidental damage' you inflicted on the car is covered under your policy?........you might get a pleasant surprise (or not!)
 
How can it be that in the old pre-electronic-everything days MB were able to devise a very simple & almost free protection system for mishaps such as this (the blade fuse in a an OVP) & yet here we are 20 odd years down the road & they apparently have no protection system in place to protect gizmos costing thousands of £££££s.

This could write off an older car!

Who is the genius who made that decision?
 
jump starting can cause your ECU to be damaged due to transient voltage spikes, even with the correct polarity, the flatter the battery the larger the spikes. my brother had his supra mk4 in for repair and they kept jump starting it, the replacement ECU 2nd hand was £650.
most cars have a reverse polarity fuse, but this only protects the wiring, anything which carries the current, fuses only protect wiring, they cannot protect the load, a spike can get through the fuse in a split second before the current melts the conductor in the fuse.
there is an element of luck involved and somtimes you can get away with it, you should have difficulty connecting the leads the wrong way so the voltage sparks should stop you quickly and limit the potential damage, as a general rule the resistive loads will be ok as they are not polarity sensitive, but any solid state items are at risk, in particular the full bridge rectifier in the alternator.

the battery does not care as it's worst failure mode is heavy cranking very high current flow over time which can distort and short out the plates. hope this helps. herbiemercman.
 
panason1c said:
In the old 'non-electronic dependent' days, you would have got away with a reverse battery connection but in this case, there is potential for major damage to have been caused. Hope i'm wrong though.
Click to expand...

I got away with doing it on my W124 (an older less-electronic design of course). Perhaps I was lucky - hope you are too.
 
You can buy an extension lead with a "spike" eliminator to use for computers so the electronics involved can't be much in the overall cost of an ECU or am I missing something here? Always thought a simple diode only let current flow one way and I know they are easily fried in alternators from bitter experience with an electric welder and an unconnected alternator!
Don
 
all fuses were checked their all ok. i hooked up the battery today and the milage on the clocks show up but nothing else. so im thinking it mite be the ecu that got fryed. if so ill just scrap the car as it will be too expensive to fix
 
Flat battery on mb SLK 230

dax121 said:
ive checked all fuses they are fine. and the relay that i taught would be for the battery seems to be for the fuel pump. part number A0025421319 V23134-B52-X336.
Click to expand...

I've been away and come back to a flat battery on my SLK 2001 compressor, I've then opened the bonnet attached my booster pack and tried to crank the engine, no joy, so I took a look at the booster and noticed I'd connected the leads wrong way round, and now I have a car with no ignition lights and it also won't crank over, please help me somebody
 
dax121 said:
all fuses were checked their all ok. i hooked up the battery today and the milage on the clocks show up but nothing else. so im thinking it mite be the ecu that got fryed. if so ill just scrap the car as it will be too expensive to fix
Click to expand...
Hi mate, did u manage to start your car and what did u replace to et it going again?
 
Syras said:
I've been away and come back to a flat battery on my SLK 2001 compressor, I've then opened the bonnet attached my booster pack and tried to crank the engine, no joy, so I took a look at the booster and noticed I'd connected the leads wrong way round, and now I have a car with no ignition lights and it also won't crank over, please help me somebody
Click to expand...

As per the previous posts suggest, you've probably caused major damage to the ecu.

All you can do now is to first disconnect and then fully charge the battery and then reconnect and check EVERY fuse fitted to the vehicle (exterior and interior fuses) and pray that you've been extremely lucky and the fault is limited to a blown fuse.
 
Syras said:
Flat battery on mb SLK 230



I've been away and come back to a flat battery on my SLK 2001 compressor, I've then opened the bonnet attached my booster pack and tried to crank the engine, no joy, so I took a look at the booster and noticed I'd connected the leads wrong way round, and now I have a car with no ignition lights and it also won't crank over, please help me somebody
Click to expand...
Hi did you sort it and how or anyone else got one which had been done the same
 
dax121 was last seen:

Mar 31, 2012

Hi and welcome to the forum. The OP ( Original Poster ) of this thread that you have reopened has not been seen on here since 2012, and did not update his story of woe.
I am sure that you have read that any reverse polarity connected battery ( if this is indeed what you have done ) MAY have done untold damage to the ECU'S and other circuits. Unless you have some knowledge of auto electrics, it may be best to consult an auto electrician and get him to give the car the once over. It may save you money in the long run.
Perhaps you could also let us know exactly what has happened ( open your own new thread in the ELECTRICS Section which will get you more views ) and what action you have taken so far. For sure you will be needing a multimeter for diagnosis and probably a wiring diagram.

Steve
 
toolman1954 said:
dax121 was last seen:

Mar 31, 2012

Hi and welcome to the forum. The OP ( Original Poster ) of this thread that you have reopened has not been seen on here since 2012, and did not update his story of woe.
I am sure that you have read that any reverse polarity connected battery ( if this is indeed what you have done ) MAY have done untold damage to the ECU'S and other circuits. Unless you have some knowledge of auto electrics, it may be best to consult an auto electrician and get him to give the car the once over. It may save you money in the long run.
Perhaps you could also let us know exactly what has happened ( open your own new thread in the ELECTRICS Section which will get you more views ) and what action you have taken so far. For sure you will be needing a multimeter for diagnosis and probably a wiring diagram.

Steve
Click to expand...
Hi purchased the car and that’s what had been done key fob works horn lights no dashboard lights no ignition power to K40 no fuses blown anywhere nothing burnt out rad fan on full ecu fan works just hoping someone solved it previously?
 
grober said:
CHECK OUT YOUR K40 RELAY---https://www.pelicanparts.com/techarticles/Mercedes-SLK230/68-ELEC-K40_Overload_Relay_Repair/68-ELEC-K40_Overload_Relay_Repair.htm
will probably contain some fuseable links to protect the cars main systems- usually best to replace the entire assembly. Try doing a search for k40 relay on some of the dedicated SLK forums- lots of pictorial howto's on there- you may have to register/ join the forum to see the pictures , pdfs etc
Click to expand...
Hi I have checked everything K40 looked perfect but redone all joints in case power to it , no fuses gone opened up inspection of the three modules nothing obvious I don’t know which one does what exactly?closed one contact coil in k40 and starter engagement for a couple of seconds.i will write an essay later asking and giving information I have done I have another k40 I tried looks exactly the same but different numbers that did nothing but I would always think like for like with part numbers?same goes for the ecu s I have some of those I have not tried them because I believe that they have to be recoded.Also no faults to read because no ignition so anything to try please let me know many thanks jim
 
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