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93 4runner electrical short...any ideas....?

956 views 10 replies 7 participants last post by  hulk240 
#1 ·
Hey guys, so here's my problem...(93 4runner , with 22re)

went to start the 4runner the other day and nothing...not even a click of the starter... so I jumped it and it started right up. Ok Im thinking dead batt or alt.....broke out the trusted volt meter, when the truck was running and at the batt it read 14.5 or so...Hmm ok maybe not the alt....turned off the truck batt read 12.3..then I just turned the ignition to on checked the reading and it read 9.3...Hmmmm Ok I have a draw or major short somewhere...So I disconected the Alt wires, starter wires, and the power going to a starter solonoid thats after market for my on board air compressor, still drawing current somewhere....when I turn the key to Ign....

So I guess my question is , is there an Ignition soloniod switch somewhere to trouble shoot, or does anyone else have any Idea's?

Tom-
 
#2 ·
Did you disconnect all the wires to the alt or just charge? I had a bad alternator the other day that charged fine but would drain the battery in a matter of 2 or 3 hours, turned out the diode was bad. It was pulling more than 2 amps with the key off, and pulled only 30 milliamps after disconnecting the the alt plug. I would try and see how many amps it is pulling rather than going by voltage. 12.3v to 9.3v is such a huge drop that I wonder if either you have a bad battery connection or if the wire between the positive of the battery and the fuse block is corroded to the point it has high resistance. I have had two toyotas that wire has corroded and caused problems. You would have to pull a TON of amps through a good connection to bring a charged battery from 9.3 to 12.3, the only way to do it with the flip of the ignition switch would be if there is a big short. Use the multimeter to measure the current being pulled across each fuse to isolate which circuit is the problem.
 
#3 ·
Yeah, I disconected the plug and the 12v wire on top of the Alt.... so yeah, alt has no wires hooked up to it....when the ignition is off, the voltage on the battery actually goes back up from say 9.3 to about 11.5, so im pretty confident its not the alternator....Hmmmm
 
#4 ·
This is strange...my 93 Runner is having the same type of problem. I'm on my 3rd Optima Yellow. Dealer told me my battery is to blame, 4Wheel parts says no way would you go through 2 Optimas in only a few months. Voltmeter says I'm losing volts through the 40 amp fuse leading to ignition switch, or alternator fuse. But the drain is very sporadic. Just when I think I'm close to narrowing down the short, it stops draining. Truck is fine for weeks, then it starts draining for weeks, and then fine for weeks!
 
#6 · (Edited)
when the truck was running and at the batt it read 14.5 or so...Hmm ok maybe not the alt....turned off the truck batt read 12.3..then I just turned the ignition to on checked the reading and it read 9.3...
You either have a bad battery, or a bad connection.

With a bad connection, no-load voltage will be high (normal) since there is very little current through the high-resistance bad connection (the voltage drop across the bad connection is small). With a higher load, the measured voltage will drop because a significant portion of the voltage is now dropped at the bad connection.

This will only be true if you measure outside the bad connection. If you measure on both the battery terminals themselves, the voltage should stay pretty close to normal under load/no-load.

If the voltage drops when measured directly on the battery terminals, then the battery is bad (or you have a REALLY big load on it, which is not likely the case unless you smell smoke...).

And I'm talking about measuring off the lead terminals on the battery itself, not anything connected to it, because that is where there could be a bad connection even if it "looks" good.
 
#8 · (Edited)
Pay attention to what Erik said. Touch the tip of the lead to the top of the lead post it's self, not the cable clamp.

Put a good battery in there, then learn to use the ammeter function on your damn multimeter.

With the key in the ON position, you're SUPPOSED to have a draw. The EFI system needs a good bit of power to run, and you've got all those pretty little lights on the dash to burn. ;)

It sounds to me like you just have a battery that's been sucked dry one too many times, and needs replaced.

Get a good battery in there (9.3V at any time is just plain too low, ESPECIALLY when you're not running the starter at the moment.)

Then take the key out, hook up the positive cable, and clamp your multimeter between the neagative post and the negative cable (set it to measure AMPS, obviously). Let it sit for 5-10 minutes, and check it. How many amps are being drawn WITH THE IGNITION OFF? Half an amp (0.50 A) is a lot of current, and will kill your battery in a couple of days. Anything under 50 milliamps (.050 A) is perfect.

If that's okay, then you should be golden. All loads found with the ignition ON should be more than covered by the alternator's output.

Checking volts like you're doing now doesn't really tell you jack.
 
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