The other day I needed to jump start my tractor, and I used my 1991 240 to do it. Worked fine, once the tractor was running I disconnected the jumper cables from the tractor, then realized that the jumper cable had popped off of the Volvo battery's ground terminal and the car was no longer running.

Now the car has no power whatsoever - no lights, no nothing.

Is there a main fuse or a fusible link in this car? Any other ideas what might cause this type of problem? Everything around the battery looked fine - no loose wires, blown fuses, etc. (I don't know what the 25A and 15A on the fender are, but they both appear fine)

Thanks for your help...

-Mike

I really don't think there is a fusable link - I would measure the voltage on the battery.

I'll bet you weren't using safe jumper leads for EFI vehicles, and the overcharge on the tractor alternator has blown some electronics in the V-perhaps as far as the EMU. I'll need to look at the wiring diagrams, but I'm sure some transistor device(s) have burned out. This will be particularly true if the tractor was diesel. It's a good reason NOT to jump start EFI cars, or with EFI cars. Perhaps the battery terminals were dirty/coonection wasn't very good?

Test the tractor battery, it may be sulfated==dead/dying-which would have pushed up the voltage on the car beyond safe. There are special jumper leads for EFI vehicles, but they are NOT a guarantee because there are many things involved. Generally, it's safer not to jump start with an efi vehicle, unless it's NOT running, and jump-start to an EFI vehicle is risky, and few (if any) manufactures recommend it. They say get a charged battery and replace it. Do not disconnect the battery on a running EFI vehicle-it will prob stop immediately with terminal electronics failures. Disregard this advice at your own risk. Unfortunately, I do understand these situations and what happens & why. Whilst in this instance I may hopefully be wrong, it is still a timely warning.

So it turns out the car battery is dead - no idea why, but I jumped it off of my truck and it started right up. I don't understand how the battery could have been discharged that quickly without something catastrophic happening, but as far as I can tell there's nothing wrong other than the battery.

I also did a bunch of web-surfing for EFI-safe jumper cables, and I talked to about 6 people who I would expect would know, and I can't find any info whatsoever on these. Manxman, are you in the US or elsewhere? What exactly is the difference between regular cables and EFI-safe cables?

Thanks,
-Mike

Curious also about this. I have jump started my 240 a number of times, and have also removed the battery whilst it was running when trying to get a second started that refused the jump start for some reason. The battery was removed from both 240's while they were running with no problems.

Have never heard of EFI-safe cables, nor can I find any info about them either.

Perth WA, Ex Tassie--

My jumper leads have a device on them, perhaps only a suppressor capacitor, but I "ASSUMED" they were for EFI cars. The RAC uses a special jumper cable set, specifically designed for efi vehicles the guys say. I've no reason to disbelieve them. Most car owners manuals I've read encourage the fitting of a fresh battery rather than jumper cables, because If a cell in the battery is bad, then the voltages can become very high. I'm surprised that any EFI car will run safely without a battery. I would've thought the regulator would be unable to hold the voltage down, but it looks like I'm wrong. Perhaps the load of the fuel pump is enough to provide safer output. I am aware that an OC car or m/cycle alternator will typ produce >100VAC before rectification and that many regulators are incapable of keeping that voltage under control without failure.. its the load that helps drag it down. I'm also aware that VCC for a microprocessor has a tolerance of <1% high, and MUST be ripple free. It wasn't normal to overspend on power supplies to give good, long-endurance operation in rare extremity/abuse.

I hold an Assoc Dip of Elect Eng (Microcomputer Technology)-I should be able to design, build and maintain microcomputer devices from concept to production. I am a hardware freak, at the antipodes of Silicon Valley. It next to impossible to develop here, as it's so difficult/expensive to get components to play with. Our market is just too small and remote. It takes too long to get specialist components, and small quantities are difficult to buy from bulk suppliers. The good store we had is now gone to the wall, and there's no-one else affordable locally.

This is the only reference I could find to those kind of cables

http://everything2.com/e2node/jumper%2520cable

Wouldn't know where to get them though, and a search on google with many different variations revealed nothing(for me)