Looking for short in electrical system

[Terrybneal]

I have a blazer that every couple of days, the battery will go dead. I load tested the battery, it is good, new alternator. Here is my question. A while ago, someone told me ya can look for a short with a test lite. I think I was told to disconnect the negative cable and put the lite between the battery and the ground cable. If the lite comes on, ya have a short. Then ya start pulling fuses till the lite goes off. Then ya found the short.Has anyone ever heard of this? Its been so long, im not sure if that is how he said to do it.

[XTEN]

Yes,Terry, that works.One thing you have to remember is that narrows it down to a circuit.It may be anything on that fuse,and alot of times its hard to figure out whats on that fuse.I had the same prob,and it was on the interior(courtesy)fuse.Couldnt find it.Changed pin switches in the jambs,took bulbs out,nothing.It ended up being a bent bracket under the hood that held up the pin switch for the burgler alarm for the hood.Someone put the security system on the interior light circuit.Found the prob by accident.Bent the bracket and pin switch back up so it contacted the hood again,problem solved.Even a blind squirell finds an acorn now and then!lolDid you put amps in it when you put the subs in it?

[Melonhead]

Yeah Terry, thats how it's done. It is best if you have a little help. Have someone like your kids hold the test light between the negative post and the ground cable. That will give you the time to pull one fuse at a time and put it back. The radio, ECM, and the interior lights should draw some. Test all the circuits other than these before. The ECM should draw the least. The more of a draw, the brighter the test light will show. I have had a radio draw too much. The truck was fine if I drove every day. Park it for a week and you can't start the truck.

[bignate]

theoreticly that would work what year?fully loaded? anything acting weird?
have you ever heard of www.identifix.com it cost to get info but ive saved a crapload of time using there site at work

[XTEN]

Yeah Terry, thats how it's done. It is best if you have a little help. Have someone like your kids hold the test light between the negative post and the ground cable. That will give you the time to pull one fuse at a time and put it back. The radio, ECM, and the interior lights should draw some. Test all the circuits other than these before. The ECM should draw the least. The more of a draw, the brighter the test light will show. I have had a radio draw too much. The truck was fine if I drove every day. Park it for a week and you can't start the truck.Melonhead,thats why I bought a battery tender.The radio.Same deal.If I drove it every few days it was fine.The reason I asked about the amp was because if you dont hook up the power antenna lead,(remote turn on)it'll draw constant power.If you do hook up the power antenna lead,and the in line fuse is blown, it'll draw constant power.

[Melonhead]

Melonhead,thats why I bought a battery tender.The radio.Same deal.If I drove it every few days it was fine.

I sold the truck, so it's not my problem anymore. LOL

[Terrybneal]

I have an amp. When it first started doing it, I suspected the amp, so I disconnected it and it did the same thing.It only does it if I dont drive it for a couple of days. Also, if im working on something on the inside with the door open and the dome lite on, it will not start after about 15 minutes of the dome lite being on. It sure acts like a bad battery, but the battery is almost new and ive done a load test on it a couple of times.

[XTEN]

I have an amp. When it first started doing it, I suspected the amp, so I disconnected it and it did the same thing.It only does it if I dont drive it for a couple of days. Also, if im working on something on the inside with the door open and the dome lite on, it will not start after about 15 minutes of the dome lite being on. It sure acts like a bad battery, but the battery is almost new and ive done a load test on it a couple of times.Terry did you disconnect both hot wires for the amp?

[Terrybneal]

Ya know, now that ya asked, I dont remember. Im thinking that I only disconnected the main hot from the battery, but not the blue wire that turns the amp on from the radio

[Terrybneal]

If the fuse was blown on the remote wire, the amp wouldnt come on, would it?

[XTEN]

Ya know, now that ya asked, I dont remember. Im thinking that I only disconnected the main hot from the battery, but not the blue wire that turns the amp on from the radioIm just poking at straws here,but did you change the head unit(radio)?maybe you got a power hog radio like Melonhead and I have.Mine's got so much crap in it that when I disconnect the battery,I got about 30 things to reset and that,I think is whats doin my battery in,all the memory.

[Terrybneal]

When I got the truck, I put in a new radio. I dunno if I caused the problem or if it was there before I bought it. When I got it, the alternator wasnt charging and the battery was shot.I have some other electrical gizmos on it also. Besides the amp, I have remote start and keyless entry. I also have a remote window roll up module.

[Terrybneal]

If I do the test lite thing, will the memory from the radio be enough to turn the lite on?

[Melonhead]

It all depends on the current. Yes it can.

[XTEN]

If the fuse was blown on the remote wire, the amp wouldnt come on, would it?That depends on the amp.Some amps Ive had will work without the blue wire,but that blue wire tells the amp when to draw power.if it is not connected,the amp draws power constantly.If the batt & alt were bad when you got the truck,theres a good posibility there was a draw prob before you got it.

[Terrybneal]

I guess this is something ill look into this weekend. I havent been driving it this week cause im driving the full size truck cause im bringing home tools from the job cause tomorrow is my last day. Also, I have the front bumper and grill pulled out. Im redoing the front roll pan..

[XTEN]

I guess this is something ill look into this weekend. I havent been driving it this week cause im driving the full size truck cause im bringing home tools from the job cause tomorrow is my last day. Also, I have the front bumper and grill pulled out. Im redoing the front roll pan..If its your last day due to layoff,I am sorry.If its retirement,congrats!Hope you find the problem.That kinda thing can drive ya nuts.Please keep us posted.

[Terrybneal]

Its my last day cause I finally got smart and found another job. Start the new job Monday..

[XTEN]

Its my last day cause I finally got smart and found another job. Start the new job Monday..Well then congrats!!!

[bignate]

did this all start after you installed one of the electric gizmos?and i have tons of problems with those remote starts ive pulled 3 of them in the last month because all the wet weather the moisture brings out the electric problems and does you alarm system or gps have a signal that it puts out every say 15 min. that lets the system see were it is located had a caddy escalade with on star the system had to relocate every fifteeen min and its supposed to be key on only but the offf signal ciruit shorted and it would come on and kill the bat evry other day.

[Terrybneal]

Im trying to find the short on my blazer today. The radio is pulling a little bit , but when I disconnected the radio, the test lite still stays on. I started pulling fuses and when I pulled the fuse that says horn/dm, the lite goes out. My wiring diagram shows that this is also the fuse that powers the dome lites and panel lites.Any ideas on what the problem may be?

[XTEN]

Terry,I dont know if anyone has a way to isolate parts in that circuit,but its always been trial and error for me.I think the smart money would be on the pin switches in the jambs.They go bad alot,and they lose ground alot.Check to see if they are rusty,or theres rust around them on the hinge pillar.Those switches are cheap if theyre bad.Maybe take interior bulbs out one at a time.The only other thing I can think of that goes bad is the headlight switch,but Id bet on a pin switch.

[oncearacer52]

Sounds like you have found the right circuit. Now you just have to find the bad spot in that area.

[Terrybneal]

After talking to Melonhead, we figured out the memory from the radio was killing the battery. At least, I think that is the problem. I usually only drive the blazer once or twice a week, but have been driving it everyday this week, so im not really sure if I have found the problem or not.

[XTEN]

After talking to Melonhead, we figured out the memory from the radio was killing the battery. At least, I think that is the problem. I usually only drive the blazer once or twice a week, but have been driving it everyday this week, so im not really sure if I have found the problem or not.My radio's the same way,Terry,its a volt hog.Thats why I mounted a battery tender on the outboard side of my battery tray.Just plug it in.My truck was eatin batteries till I did that.Two,goin on three yrs and battery still good.I thought when you tested it,you took the radio fuse out and still had a draw on the int light circuit??

[oncearacer52]

I seriously doubt that your radio memory will drain your battery in a week, or a month for that matter.