Just bought a 93 940 wagon and was told it needed a new battery. Put it in and started it up and it runs perfect. Drove it home and the next day, the battery was dead. Jumped it and it started and in a couple minutes it was charged enough to start and run on its own. this time when I shut it off, I pulled the cable off the battery. When I tryed to start it again, the battery cable sparked when I hooked it up, but it started and ran ok. When I shut it off, I unhooked the cable but there is no spark and no signs that there is a short. Five minutes later it sparks again and there is something draining the battery pretty hard too. I tryed to find it but could not. Once it is started, things seem to be ok. When it is shut off things seem to be ok. After it is off a couple minutes, there is a heavy drain on the battery and it will kill the battery in just an hour or so. Any help with this would be appreciated.

A few months ago I had a bad Fuel Injection relay on a 240 (same as 900). A broken/missing armature spring let the fuel relay points touch just enough to draw about 4.5 Amps — through the fuel pumps (but not enough to run them).

You believe, "there is a heavy drain on the battery and it will kill the battery in just an hour or so", which seems to point to something other than a bulb. Try pulling the FI relay (White case, location in the FAQ).

If no luck on that, I'd pull HALF of the fuses at once. If that doesn't help, put them back in and pull the other half. If it is (hopefully) fuse-related, the culprit should be in one bunch or the other — then keep half-splitting till you've narrowed it down to one fuse. Then we go from there. I have wiring diagrams.
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Bruce Young,
940-NA (current)
'80 GLE V8 (Now gone)
'83 Turbo 245
'73 142 (98K)
'71 144 (track modified--and still here)
New 144 from '67 to '78
Used '62 122 from '63 to '67

I agree with Don. With the motor off, disconnect the negative battery cable and Connect an amp meter between the battery post and the cable. If somethings draining the battery, you'll see it register on the meter. Then remove the fuses until the meter drops. The fuse that caused the meter to drop is the circuit that's shorting/draining the battery.

Thanks for the advice Don, this is what I intend to do tomorrow when it stops raining. I just thought that there was a problem that is common that causes this problem.I'll let you know what I find

Check the less obvious things -- glove box light, under hood light, vanity light (backside of the passenger's visor), stereo amplifier, etc.

When you know it's drawing current, try pulling each fuse in sequence to find the offending circuit.
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Don Foster (near Cape Cod, MA)