Lyall

My batteries went flat last night last night and I don't know why. Disconnected the leads and charged both separately and they held charge. When I checked for resistance between the positive cable (drivers side only) and ground' it showed 2 ohms (almost dead short). When I connected only the drivers side battery, I saw a small spark when the cable touched the battery post. How do I check for battery drainage and what is my next step to source the problem? Could the preheaters be on? How would I disconnect the heaters?

cdennyb

Mine sparks too when I hook them up, don't think that's a heater problem. Best bet would be to do a load test, Pep Boys, Kragen, Firestone, etc. can do a load check on them and let you know. Sometimes an alternator diode array can go bad and cause a battery drain. Something to look at after battery test comes back good. Always do the cheap stuff (tests) first.

torquefan

Testing for a draw is somewhat different if you have a 2nd gen quad cab. They have seat belts built into the seats which contain an electric lock solenoid on the retractor. These retractor locks will draw power, I think for 20 minutes or more, after the truck is shut off and the doors closed. As soon as it sees a door ajar signal, it will power these up again. Keep this in mind when testing for a draw.

Lyall

Hooked both batteries up again and the truck starts and runs OK. Disconnected both batteries after it started and it runs OK so the alternator should be good? Voltage reading on the dash says 14volts.
Disconnected the 140 amp fuse in the fuse block under the hood and the 2 ohm short disappeared. Does this mean something?
Tapped the starter in case the contacts were welded.

gorms

Well as "close" to a dead short a 2 ohms sounds, that should only draw about 6 amps (12 volts divided by 2 ohms equals 6 amps). Still a good load, but not enough to be the starter or heater, imho. I'd start by disconnecting the whips going up to the seats, then checking. Or pulling one fuse at a time in general, but that 140 is for the alternator I thought? Making a good point by cdennyb, disconnect the alternator and checking. If that 140 feeds the entire fuse block soley then it basically tells you nothing, but if that is the alternator only (not disconnecting battery power to the fuse block) fuse, alternator would be your best bet.