maf5279

The truck is a 99 2500 4x4 w/ a 350 motor w/ right around 100k miles. Had fuel pump replaced by dealer after about 2 months of hard starting problems. Fuel pump works fine but now I have to jump start the truck every morning . Battery tested ok and alternator works fine, but something seems to be draining battery after the truck sits for 3 or 4 hours. I have a snow plow , salt spreader, and two way radio all hooked up and have tried unhooking them from the battery overnight, but the problem still occurs. The cables seem to be free of corrosion and the battery is about a year and a half old. Any suggestions would be appreciated.

sc_customs

Do you have an aftermarket alarm system on the vehicle? I have been having the same problems and I isolated the problem to my alarm system. It seems when it is active it draws current from the battery, therefore killing it by morning. Just a thought.

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2000 Silverado 4.8L V8 (Converted from 4.3L V6)
Edelbrock Ceramic Coated Headers
K&N Fipk Gen. II
Superchips MAX Tuner
Flowmaster 40 Series DF w/3" pipe
Poweraid TB Spacer
Flex-a-lite Electric Fans
3.73 gears w/Eaton posi
Whipple on hold
And those are just the performance mods...

maf5279

No alarm, but I do have an electric trailer brake system that hasn't been hooked up in years. Could it possibly be the starter, due to the fact that I was putting so much strain on it for a couple months?

muff34

Disconnect neg battery cable ,try hooking up a test light Between Neg Battery post and neg battery cable .if there is a power draw light will come on . start pulling fuses one at a time till light goes out. do interior light first as the door will be open. when the light goes out you`ve found circuit that is causing problem,

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maf5279

Thanks, your reply really helped. I traced it down to the "battery, fuse block busbar" fuse under the hood. I don't have a wiring diagram , but I think that runs power to the transfer case, the hazard/brake lights, and maybe one other fuse but I'm not sure. Is there any way to tell which of these might be causing the short?

sreve

what muff34 said only with a dvom set to ma. 50ma or less is considered normal most seem to run 18 to 25ma. 25ma will dimly light a test light so the dvom is nessasary. have seen 75 or 80 that did not cause problems on drivers. pull the rap relay before you test.