Parasitic electrical draw

BlenderWizard · November 25, 2016

So something is draining my battery on my 2003 Tahoe overnight, and I am pulling one fuse every night to try to track down the culprit. I pulled the fuse marked SBA (supplemental brake assist) last night. Reinstalled it, and it fired right up this morning. I am repeating it tonight to see if I get the same results. If that is the actual problem is the SBA motor just in need of replacement?

carkhz316 · November 25, 2016

Oh man, one fuse a day to test......gonna take forever. If it is indeed your culprit, you lucked out you found it that fast. Do you have access or knowledge to use a multimeter? Doing a proper parasitic draw test will narrow it down quickly and confirm the culprit.

BlenderWizard · November 25, 2016

I tried that, but it read 0 amps when I tried that test. When I switched it over to volts, it got an appropriate reading. I could try another multimeter, I guess, but I only have the one...

carkhz316 · November 27, 2016

What amperage scale do you have the meter set to? Most have a 10 amp setting; and a 1 amp setting that will display in mA. Voltage will tell you nothing. I'm assuming it read somewhere around 12V? I'm assuming you had it on a 10A setting and were "only" seeing .1 or .2? If so, that is your parasitic drain, as that is actually hundreds of milliamps of current draw, which WILL drain the battery in a few days time. Let us know what you find.

BlenderWizard · November 28, 2016

Well, it seems as though my initial analysis of the situation was incorrect. Went out this morning, and same thing - noting when I turned the key except lights and radio. Left the key in the ON position and went in the garage to get a hammer. Tapped on the starter, got back in and it cranked right up. So, now I have determined it is either the starter or ignition switch. Wish I'd only done one of those things this morning, but now I have a short ruled out, and I can quit pulling fuses..