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Discussion Starter #1
Battery was flat this morning so i got the jump leads out and connected them the wrong way!:tut: there was a little spark and the jump leads became very warm! the car then refused to do anything when the key was placed in, no dashboard lights nothing, i tried another battery and interior lights worked but still no acknoledgement when key inserted could this be a fuse? if so which one? any help would be great.
 

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i wouldnt be surprised if you fried the ECU. Its advised not to jump start a car but to put the leads the wrong way round..... Hope for you wallets sake its just a fuse
 

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First check those big fuses on the battery next to the positive connection.

Then take your time and check one by one the ones under the steering wheel. Don't get them mixed up, remember where it was when you take it out as there are some empty spaces.

Wish you luck!
 

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Not sure whats its like on the Alfa, but the alternator will probably have a very large value fuse hidden somewhere, maybe its this that has blown, so anything engine related is not working but things like interior lighting are ok.
 

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If you have banged 12v down the chassis.... that could prove expensive. The main fuses will blow, but not quick enough to save the ECU.
Its going to be total luck. You could get away with a few blown fuses, or you could have caused a lot of damage.
Did you jump from another battery or a car? If its from another car, then the amps supplied will have been pretty brutal.
Good luck and fingers crossed
 

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:( Good luck.

They do attempt to guard against reverse polarity so hopefully it will be ok.

If all the electronics in a modern car blow you are basically looking at a write off considering the costs involved to fix it.
 

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We don't see Alfas but the numptys at work often jump start Renault and Vauxhall brand new non starters with 24v if 12v doesn't seem to be working. Cringe! I've not heard of any major damage and I'd be surprised if a few hadn't been connected the wrong way 1st time. There may be an easy/cheap fix for you, hopefully no expensive damage.
 

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24v:eek:
Reverse power on electronic components are bad but like I said they do tend to build in mechanisms to protect against it.
Then again normally you realize your mistake when you connect it and do not attempt starting with it the wrong way around.
The flat battery will also absorb some of the strain which should help to protect a bit as well.
I am holding thumbs for a safe and cheap recovery.
 

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Discussion Starter #11
Thanks for all the replys and the genuine concern it is most appreciated, should be back early enough tommorow to get the multi meter out and start testing those fuses!!!! fingers crossed....... will let you all know the outcome.
 

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these ECU's are normally off the shelf bosch or magnetti units. modern electronics should be protected against reverse polarity, just a simple diode should do the trick. might be a main fuse. if ECU is fried then see how much a repair might cost or a re-conditioned unit.
 

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these ECU's are normally off the shelf bosch or magnetti units. modern electronics should be protected against reverse polarity, just a simple diode should do the trick. might be a main fuse. if ECU is fried then see how much a repair might cost or a re-conditioned unit.
:thumbs:
 

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I suspect serious damage here unfortunately, its fine to have polarity reversal protection by diode is fine on inputs, but the majority of the ECU output is on switched negative and youve just sent the wrong polarity through the chassis and into the input and output of a hell of a lot of modules.

These latest Bosch EDC are quite a bit more complex than older ECU's, you also have the body computer etc. live at this time.
 
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Someone else did this not long ago, do a thread search.




From my experience jumping these cars is more bother than it's worth.


Best case you end up with a load of errors that need resetting, worst case you
can fry the ECU, even if you connect it up right.



Use a battery pack, it's safer.
 

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Discussion Starter #16
Update.

I have blown the Main mega fuse which connects the battery to the main supply to fuse box. Its a 150amp fuse would you believe, cant get a new one till Tuesday and a new battery required only £70 from GSF (2 year Guarantee) which i thought was reasonable compared to £124.99 from alfa Chelmsford.

Cant be sure if i'm completely out the woods yet but the early signs are looking good!

Maybe time to relax that squeaky bum that's been playing me up all week!!!!

Will keep you posted and thanks again for all the sincere messages
 

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Good luck blowing a 150a fuse I didn't even know they used fuses that's so strong.
 

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By the time a 150a blows all electronics will be up in smoke. Hopefully it worked.
 
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