hey guys i have a power short somewhere in my pickup. its a 94 pickup 3vze basic stock stuff. so my question is how can i find this damned short? i have visually inspected so much wiring my brain hurts and i cant find anything grounding out.i also checked my alternator and got a brand new battery less than a month ago. any help with the troubleshooting would be great.

 

Sounds like you might have a grounding issue.

checked for brake light switch out of adjustment.

glove box light on all the time or the dome light.

alternator has low output.

A short is going to open your circuit protection melt wires to the circuit opens or burn the whole truck.

Some real world Voltage numbers are always helpful.

if it is a parasitic draw put a light on the ground cable circuit and pull the fuses to it goes out.

 

Yeah, I've done the same. Those dang electrons are just so small! How am I supposed to see 'em?

You have an electrical problem. You work on it with a multimeter. Any other tool (test light, power probe, etc.) is just to spend time UNTIL you pull out the multimeter. (no multimeter? No excuse for that! http://www.harborfreight.com/# That's right; at the time of this writing, a perfectly good multimeter is FREE!!!)

You hook the multimeter up to measure the current (amperage) being put out by the battery. It should be in the 10s of milli-amps (to keep the clock and radio running); in your case it may be close to an amp (1,000 milli-amps). So use the 10-amp scale or you'll blow the meter's fuse. Then start pulling fuses until you get the big drop in current; that's the circuit that's got the parasitic current draw.

Be careful to not try to start the truck with the meter on! Starting can pull up to 100 amps, which will incinerate an ordinary multimeter on the 10A scale.

 

I agree with scope on this one you need to check this with a multimeter, a test light only works if you have a big draw. Make sure the meter is set to 10amps then unhook NEG battery cable and hook meter up in series (red probe on cable and black probe on battery). You should get a initial spike but after a few minutes the reading should drop. Rule of thumb is 50ma (0.050) and below is ok, anything above that and you have a draw and you would start pulling fuses at this point.

 

Some times if one is challenged in electrical trouble shooting !!

Using a new Multimeter is stressful enough trying to measure current draw even more so.

Since most would not sit down and read the users manual Then the low end Meters don`t give much for directions in English.

 

If you don't have a meter, here's a coupon for one at HF. Everyone needs to start with a cheap meter as you're going to blow it up eventually.


http://widgets.harborfreight.com/wsw...061_c0316b_ext

 

How did you check the alt ?

A stuck relay on could cause the draw. If the horn does not work then maybe that relay is your prob.

Try jerry rigging a 12v bulb between the battery and the ground cable. The parasitic draw should be enough to light up. Then start tapping "stuff" under the hood.

 

Here are the measurements I made some time ago. Maybe they could be used as a reference. Notice the difference in parasitic draws between my old stereo/amp system to the new Alpine CDE-153BT head unit w KTP-455U amp.

Current Draws (motor off) OPTIMA Yellow Top Battery 47AH (tested 12-12-13, re-tested 1-21-15 @ 44AH), 15AH available
Key out .12mA/125K hrs/14yrs (Old head & amp 8mA/1875 hrs/78 days)
Key ACC, all off 115mA/130 hrs (Old head & amp 689mA/21 hrs)
Stereo loud, Jazz 210mA/71 hrs, Hvy Rock 390mA/38.5hrs, Keb Mo .240mA/62.5hrs (Old head & amp 3.3A/ 4.5 hrs)
CB rec 1.0A/ 15 hrs
CB trans AM, min pwr 4.15A/3.16 hrs, max pwr 6.5A/2.3 hrs
CB trans SSB, max pwr 1.2A avg/12.5 hrs
CB w/ amp ON, rec .96A/15.6 hrs
CB w/ amp ON, trans AM CB 4.15A + Amp 9.0A=13.15A/1.1 hrs
CB trans SSB, PA ON, max pwr hrs [overloads meter]
Headlight, Low beam 11.7A/1. 3hrs, High beam 15.8A/.95 hrs

 

ok i went and picked up a brand new high end free multimeter from harbour freight. and i had the alternator checked at oriellys. im going to start stabbing away at this again today and hopefully end it. its getting really annoying to have to disconnect my battery every time i go to work or have to park for more than a couple hours. wish me some luck with this. im going to start with the MM on the battery and pull fuses till the amps drop.

 

Ok I read from the neg post to the cable its drawing .16 amps with the key off. As soon as I pulled my 15amp Efi fuse it dropped to .01. Does that sound right or I am even doing this right?

 

0.16 amps is 160milliamps, so you would get a more accurate reading on the 200m (milliamp) DCA (direct-current amperes) scale. 0.01 is the lowest possible reading on the 10A scale, so it could be 10ma or maybe 20ma or just 5ma. So change scales.

BUT: A car battery has around 40 Amp-hours (btu44 thought he only had 15 "available"). At 0.16 amps, your battery should last close to 100 hours. That's still too short (something is drawing excess current), but you may need to look farther.

First, check that your battery is charged. Is it about 12.6v at the battery? Next, check that it's charging; with the engine idling, you should get about 14.1v at the battery. If it's significantly less than that the battery is not charging, even if the alternator is "good."

Next, hook up your ammeter (I'd leave it on the 10A scale). Now sit and watch it for at least 10 minutes. 0.16 shouldn't run the battery down, so you might have something (alarm system?) that wakes up ever few minutes and uses lots more power (so don't use the 200m scale, just in case).

 

i checked my battery and it was 12.5v and it was the only draw i could find by checking the fuses. now my battery is never fully charged. i jump it when it dies and however charged it gets is how long i drive for. when it dies and i jump it and drive 15min to work it will be dead in eight hours. no lights or anything. thats why i disconnect the battery so i dont have to always jump it.

 

and no alarm system in this

 

Trust O'Reilly? Still need to verify.
Disconnect. the "B" wire for alternator screw post. Measure resistance from screw post to ground.

 

"BUT: A car battery has around 40 Amp-hours (btu44 thought he only had 15 "available"). "

I used 15AH as a limit when using the stereo or CB while camping. I figure 2/3 capacity reserve would safely start the truck.

 

What's the battery voltage with the truck idling? It better be about 14.2V

 

Ok I disconnected the efi fuse and let it sit for 12 hours. Usually it would be dead in this time. But I plugged it back in and it fired right away. Now how do I see where the problem is with my fuel pump?

 

B+ on the diagnostic connector is south of the EFI main relay, which is south of the EFI fuse. Why don't you check that with key-off. If you get 12v there, it sounds like the EFI relay is not opening with key-off.

You should also listen carefully for the fuel pump (the COR is south of the EFI main relay). I don't think that's it, because it probably pulls more than 160ma, but I'm not sure your draw is that small anyway. If the fuel pump remains on it won't affect your drivability but it probably will run the battery down in the way you describe.