V70 2.3 w/ crossed battery terminals
 

Hi guys, i'm negotiating a 2000 V70 2.3 which the previous owner said that a friend, while doing a service, crossed the battery terminals and the car "won't start and nothing lights up in the dashboard".
So, knowing that these cars have lots and lots of electronics, how bad it's this?

Do the just blow some fuses and spare the electronic modules or they just die along?
I've read that the main culripts when crossing battery terminals that the car won't even start are the "J fuses" in the fuse box, is it correct?

Thanks in advance for any replies.

Hi, I'd suggest checking all fuses/fusible links as a start. It's possible though that even if fuses have blown and protected some circuits that damage has occurred to others.

Personally, if I was looking at a car that was completely "dead" and I knew the battery had been connected backwards I'd price it as scrap value. It's a big gamble really, do you try and replace any obvious blown fuses & risk the car starting right up and the seller deciding to up the price, or do you buy it "as is" and take the chance that it may be a parts car?

There is also the possibility that the electrical mistake & subsequent fault might be a cover up attempt to sell a car with a ruined engine/transmission etc as a potential "easy fix".

It depends on how much you want this particular car/how much of a gambler you are. For me, if the price is close enough to scrap/parts value (or I could get another of the same model, good runner with accident damage to swap parts between and make one good car) then I'd probably roll the dice.

also you may have blown the alternator rectifier,
remove the CEM and have a good look at that,
The ECU will be blown, you may be able to clone that if the flash rom and eeprom is ok,
that Dave

if you are thinking about getting this, I would say walk away,
Dave

That's a good point, i haven't thought about that.
Here where i live, Volvos are PRETTY rare, you don't find any of them even in the city centers, nor for sale.
And the seeler isn't that great, the comments about it (it's a dealership, in fact) isn't comforting either.

So, knowing that these cars has a lot of electronics, i'm very afraid of getting one, even though it's basically, my dream car.
Thanks for the advice, i'll try to see the car even in that condition and i'll post some updates tomorrow.

is it hard to do without any specific tools?
It's in the engine compartment, right?

It the fix was simple then you can bet the owner would have done it already. The chances are it’s been to someone who knows at least a bit about cars and they have said to sack it off. It could be so much hassle so as above I would value it at scrap so at least you can’t lose.

All automotive electronics are tested for reverse battery connection - you will probably have blown some fuses, but there would have to be another fault present before it damaged the electronics.

That being said, other users warnings of it masking other issues should be taken into account!

yes and yes

you will need to de-solder the flashrom from the old ecu and reprogram the new ecu, and you need to read the eeprom in old ecu then program the data in to the nee ecu,

or unsolder the eeprom and flashrom and fit them in the new ecu
only if chips are ok and working,
Dave

I'd ignore the doom merchants initially. Go and check some fuses, look for the main fuse, I suspect it might be blown. Had very similar with an impreza recently. The main fuse had blow. £3 for a new one and it was back to normal afterwards.

Its a fairly safe bet that the fuses have already been checked. The vendor is a car dealership & presumably has the ability/contacts to have the obvious stuff checked out. If this was an easy repair it would probably have been sorted. 2 people have already thrown the towel in... someone got rid of it in the 1st place and the dealer is unloading it now.

You say Volvos are rare in Brazil and you don't even see them in the cities. Even if you could get the problem diagnosed you may find it impossible finding used spares (or firms knowledgeable in repairing Volvo electronics).