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Old 04-14-2012, 10:12 AM
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Need help locating a short to ground. Electrical guys please read

Hey guys. 96 CCLB 4wd E4OD, Intake, gauges.

Few weeks back replaced the fuel lines coming off the fuel bowl. When I went to hook the batteries back up and crank I got white smoke billowing up from behind the dash. Found out that a diode in my Wait to Start light module-thing had fried and was smoking at the circuit board. Now after I crank my truck and pull the key, my abs light and charging system light are both still dimly lit.

Can somebody please school me up on how the heck to find where my electrical problem is? I have limited knowledge of electrical systems and diagnosis but I'm a quick study. I need this truck up and running like yesterday. Please give me a hand here!
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Old 04-14-2012, 10:58 AM
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Ok guys. Took out the multimeter and checked all my fuses with the key pulled. None should have any power whatsoever, right? Didn't find any in the in-cab fuse panel. In the underhood power distribution box, though, 20A Maxi Fuse #9 (listed as Powertrain Control System) is showing a reading. It's only showing a tiny amount (I'm not great at reading multimeters; set at 200m on the DCV range I'm showing about .7)
Now I'm assuming this circuit is my PCM circuit, so why is the PCM pulling voltage? How can I locate the source?
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Old 04-14-2012, 11:14 AM
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I wish i could help. I'm not bad with electrical stuff but this is beyond my knowledge. I can tell you though that your PCM circuit will always have a VERY slight draw because it keeps things alive in the memory, KAM. But it is minuscule amount at most.
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Old 04-14-2012, 12:49 PM
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Quote:
Originally Posted by Jake View Post
I wish i could help. I'm not bad with electrical stuff but this is beyond my knowledge. I can tell you though that your PCM circuit will always have a VERY slight draw because it keeps things alive in the memory, KAM. But it is minuscule amount at most.
Thanks Jake. I was just talking to a buddy of mine and he told me about the KAM. So now I'm back at square one. I pulled my cluster to see if I had any fried electronic components. So far nothing. I have no diagrams so I'm following the light bulbs and the printed circuits to the pins on the connector that correlate to the two lights that are staying lit.

If anybody has any diagrams let me know!
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Old 04-14-2012, 01:17 PM
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I would normally say you have a bad ground but i dont know with things frying under your dash!!!

If you disconnect the batteries and then touch the yerminal on the batt post, is there an arc of electric? Shouldn't be enough to notice. This would tell you if you have a drain.
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Old 04-14-2012, 01:28 PM
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Yea there is. And if I touch my multi meter between the neg terminal and a chassis ground I get about a 12v reading, so I definitely have a drain somewhere. I know it's somehow involved with the circuits the two dash lights are on so I'm pretty sure I have a ground to hot somewhere. Just don't know where to look, you know?
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Old 04-14-2012, 02:53 PM
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You can try pulling 1 fuse then see if the drain goes awau. If not, replace that fuse and pull the next one.
if it does stop, that is the problem circuit.
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Old 07-31-2012, 11:05 PM
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Well the issue is fixed. Bad insulation caused two wires coming from a sensor near my hpop made contact and fried my pcm. 6 months later I now have a new pcm and no more issue. Thanks for the help guys!
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