1997 850 wagon Did I fry something?

[Tobers]

My daughter's 850 wagon sat for a while, and the battery was dead. I jumped it fine. Ran a mile. It died. I jumped it fine again. It died again. I think it was simply really dead. So I went to jump it again, and then planned on letting it idle for an hour. This time, however, I jumped it from my son's beater truck. I connected black to black and red to red. There were a bunch of sparks. I double checked again to be sure the lines were red to red and black to black; they were. More sparks. But no voltage to the Volvo. So I looked more carefully at his truck. Somehow the red rubber cover was on the GROUND line. Bottomline: I connected the batteries twice, while the truck was running, to the Volvo, with the cables wrong. When I switched the lines, I got 12v, and it turned over. and over. and over. But wouldn't fire up. Did I fry something when I hooked up the batteries backwards? If so, what now? Thank you. Rick

[misha]

Check ALL fuses first.
If you were lucky you will get away with fried battery & alternator only.
If you were not then....alt,ecu,battery,relays....etc.

[abscate]

There are some fusible links from battery to fusebox that probably are now bubbly and melted. You will need to replace them.

Reversing polarity on electronically managed cars like Volvos, and just about every car nowadays, is not good.

[E Showell]

Never correct practice to go post-to-post, post-to-post on the batteries when jumping. That approach never ends well and it is surprising the number of folks who don't know proper connection sequence and location. Since winter is coming and there is bound to be the inevitable slew of dead battery emergencies:

Jumper cables are correctly connected:

1) Positive battery post of running car to positive battery post of dead car;

2) Negative battery post of running car to metal ground in engine compartment of non-running car (I usually try to use a lifting eye or some such -- not a fuel line).

Once the non-runner has been started, the jumper cables should be removed in the reverse order from application.

[scot850]

Well written Even! Always amazed at how many folks get that wrong! You have reminded me to go check the 06 XC70 battery and starting options as the battery is under trunk floor.

Neil.

[erikv11]

Crossing the cables on athreen 850 will fry one or all of the J relays in the box at the cowl.

Get some from a junkyard, they otherwise basically never fail. Often this is the only problem, but sometimes the alternator will be cooked too. I can send you some relays for a few bucks if you need. But I don't have any spare alts ...

[tryingbe]

I'd say at minimal, both alternator and battery is toasted. You will have to diagnosis or send the car out to be diagnosis and see what else is damaged.

https://www.matthewsvolvosite.com/forums ... hp?t=71902

[bmdubya1198]

Never correct practice to go post-to-post, post-to-post on the batteries when jumping. That approach never ends well and it is surprising the number of folks who don't know proper connection sequence and location. Since winter is coming and there is bound to be the inevitable slew of dead battery emergencies:

Jumper cables are correctly connected:

1) Positive battery post of running car to positive battery post of dead car;

2) Negative battery post of running car to metal ground in engine compartment of non-running car (I usually try to use a lifting eye or some such -- not a fuel line).

Once the non-runner has been started, the jumper cables should be removed in the reverse order from application.

This is good practice. You do NOT go negative terminal to negative terminal. The negative cable should only be grounded on the car receiving the jump, NOT connected to the negative battery terminal.

[rspi]

A common stalling problem with P80 Volvo's is the fuel pump relay, especially in the cold.