[andyvh1959]

Can always do the basics:
1. Battery terminals clean, no corrosion/green buildup on the terminals
2. Search the systems for the drain source

To do that you'll need a volt-ohmeter, or find someone that has a volt-ohmeter. Disconnect the negative cable at the battery and clip the negative probe from the meter to the cable. Set the meter to AC-Amps. Touch the positive probe from the meter to the battery negative post. For a normal draw the meter should show 0.05 amp, or 50 millamp, with the ignition off.

Anything higher than 50 millamp indicates an abnormal draw. You can them use the meter attached to the cable and battery post, and go through the fuse panel, relay panel, connections panel, and systematically take out a fuse, check the meter, or take out a relay, check the meter. Go through every fuse/relay/connection. When you find the connection that makes the meter drop to zero, you've found the suspect circuit. From there you can either dig into that circuit or function and find the connection or part causing the draw. Or, once you identify the draw, take your vehicle to a shop and tell them what you found. A reputable shop can repeat your test, or take your findings, and find the trouble.

 

[andyvh1959]

Good info. I have used the amp draw test method on motorcycles, which is great because everything is in a much tighter overall package. Have not yet done it on a car or pickup. Biggest thing is tracking down the circuit that has the draw. Once that is found its pretty much just follow the wiring to the problem spot.

Remember too, keep it simple BEFORE replacing parts. I had a lawn tractor draining the battery, would not crank over, but I could pull start it. And sometimes it would start with the key, weird. I replaced: the starter, the starter reply, the ignition switch, the battery, cleaned the contacts at the battery and frame, all with no consistent results. Hmm, took the original ground cable off (this is an 82 lawn tractor), connected my ohmeter, no continuity, flexed the cable, continuity! Had I just checked the ground cable 1st, would have been done in 1/2 hour, and saved $$$