kashin18

on my 91 blazer how can I find the source of a short? when my blazer sits for more than one day the battery is completly dead. I assumed the battery was shot because it was 7 years old but I put in a new battery and after sitting for the weekend it is dead. Once I charge it and try to put the negative terminal back onto the battery post it archs really bad as though something is drawing power or turned on. I am pretty knowledgeable with vehicles but this one has me stumped. need to find the problem asap. Every day driver, Thanks

MDTAHOE

You need a DVOM ( digital volt ohm meter) set on amps. Disconnect the negative battery cable, attach 1 meter lead to the cable and one to the battery. You need to have less than 25ma or as close as possible. Start pulling fuses until the amperage drops. Then find out what is on the circuit and staying on. Usually it is a under the hood light,glove box light on the lights on the vanity mirror (visor mirror).

kashin18

when I set my DVOM to amps and connect my black meter lead to the ground wire (disconnected)and my red lead to the positive on the battery my ma is 00.00. When I connect my black meter lead to the ground cable and the red lead to the negative post on the battery it reads 18.75 then starts to drop and the wires on the DVOM get very hot quick. Am I testing it the right way? I can work on demo derby cars but this electrical thing is confusing to me.

MDTAHOE

Does it say 18.75 ma or 18.75 a ?

tm4hammer

That was some good advise MD ! He can further isolate at the connectors next to the firewall seprating front from back! if need be or he can look and find a squirlle nest above his fuel tank and chewed up harnesss like me a couple weeks ago on the burb ! ha ha dont ask ! i have no idea ! but i do have the cure a 50 to 100 yard cure damn tree rats anyway they also make a tool called the powershot it is one of the best in quick tracing shorts or electrcal problems can both check g or energise a circuit and i believe the more expensive model has a DVOM installed in it , a must have quick check tool along with a good DVOM for todays mess of electrical systems which is about all it seems has been coming my way lately sorry to butt in boss !i just feel his pain

kashin18

it dosent say ma om just 18.75. I found that the power locks and rear defrost are on the same circuit and neither is working. I removed the larger 30a metal fuse that controls that and my ground is not arcking when connect it back to the battery. 2 days and battery not going dead so I think it is in the locks or rear defrost. Thank guys.

truesoldier

This exact same thing happened on my 97 blazer. Would sit for a day and be completely dead like something was draining the battery over night. Well turns out I took it to 5 different mechanics and they all told me ECU every single time. That might be it.