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I looked for a short in wiring harness and watched a video on youtube. The guy described a method that you disconnect the positive post of your battery. Then use a tester to see if the lamp lit when you attach the aligator head of the tester to postive post and the other end to positive cable you just disconnected fron positive battery post. If the light lit so there is a [/b]short and you check each fuse one by one to find the fuse that off the light.
Anyway I used this method on my truck. I disconnected all four positive battery posts. Then I saw the tester lamp light turned on when checked it between positive post and positive cable and light went off when negative cables that go to starter are detached from negative battery post.
Now the question is how is that possible?
I checked sll the cables that go from batteries to starter. Nothing unusual.
(02-10-2018 )alborz Wrote: [ -> ]I looked for a short in wiring harness and watched a video on youtube. The guy described a method that you disconnect the positive post of your battery. Then use a tester to see if the lamp lit when you attach the aligator head of the tester to postive post and the other end to positive cable you just disconnected fron positive battery post. If the light lit so there is a [/b]short and you check each fuse one by one to find the fuse that off the light.
Anyway I used this method on my truck. I disconnected all four positive battery posts. Then I saw the tester lamp light turned on when checked it between positive post and positive cable and light went off when negative cables that go to starter are detached from negative battery post.
Now the question is how is that possible?
I checked sll the cables that go from batteries to starter. Nothing unusual.

Well what exactly is going on? Sounds like the test your describing is a test for continuity
Wouldn't the tester just complete the circuit and light up or blow the light every time?
If your using a light tester for a 12v circuit, when you place the tester where you described then of course it'll light up. You made a simple circuit. Pos. post then the load then the neg.(ground). Your's is like this, 12v source(pos. post) connected to the little itty bitty light in the tester connected to the huge long battery cable that ends on the starter post(which is now acting as a ground for the itty bitty tester light). There is more than enough resistance in that big and that long of a cable to act as a ground for a little light bulb in a light tester.

With the ground post you have no 12v (pos) source. Its all grounds on both sides of the tester. Nothing there to light it up.

You may want to share the youtube video link so we can see what exactly they were testing and how.
Youtube is a great place to troll the ever living stupid out of society (tide pod challenge) and also home of the dumbest techs screaming they know what they're talking about when they very clearly don't.
if you are still reading this, why are you looking for a"short" ..??

using a low range dc amp clamp, there should be <200 - 400 ma static draw depending on your electronics

it takes time for Modules to sleep after key off

a place to look for a high draw is the Alternator

I can help you determine amp draw circuit-by circuit if needed
(05-17-2018 )Bruce_Sloane Wrote: [ -> ]if you are still reading this, why are you looking for a"short" ..??

using a low range dc amp clamp, there should be <200 - 400 ma static draw depending on your electronics

it takes time for Modules to sleep after key off

a place to look for a high draw is the Alternator

I can help you determine amp draw circuit-by circuit if needed

I think this guy has been reading too many text books. Current draw is different for every truck, especially when you start factoring in gps's, qualcomms, hidden vehicle trackers, and a dozen other things you find in a typical truck these days. Only 200 - 400 ma sounds more like a car to me. However it is not a bad idea for finding battery draining gremlins...


Something like this comes to mind.
Link: http://a.co/iwr7oIe


Not a bad idea for things that draw power, but 1/3 the wiring on a truck these days is also sensors and signal wiring. A clamp meter will not always be so useful on those.
I can post a chart showing measured voltage drop (Mv) across fuses that will help troubleshoot each individual circuit if anyone would like it
and yes, 400ma is for no Acc loads, just Modules in Stby
looking at the Amazon linky ...
You should get a Low Current probe for +/- $100...
I use a Hantek that cost $65, but it's for use with my DSO, no display on it
Here are good figures for a B series
If the engine is an ISB, the ECM will draw between 8 and 12mA at all times.
If the trans has a PCM, it will do likewise.
VCRs run (on average) 34mA on standby.
An 8D battery should be to support these loads for about 30 days with little or no effect.
Sorry I do not have figures for say, an ISX, but still, over 500Ma is trouble territory
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