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there are only two ground wires on the modified harness, that he was to connect to something. guess my same ground theory wouldnt work, as the injectors pulse...I wonder why its just the ignition having issues then?
the common coil grounds lead to a ground, not the pcm, for them to have voltage with the key on, it almost seems like they are connected to something 12v switched. cause you cant have open circuit voltage unless its getting current somewhere. if you ground a wire to the block, put a test light on negative side of battery, you wouldnt expect the wire grounded to the block to have voltage, yet with the common coil ground wire, that is exactly what is happening. as its disconnected from the coils themselve, which means the other end should be at a solid ground...but...and since the only two harness grounds are at the same point...and with the injectors working...this could or should mean that wire is on its own somewhere...rubbin up on something with voltage, actin like its a stud...haha
we need a wire whisperer :D
our harness is 7 wire connection, as far as coils to pcm harness.
both 7 wire connections for each group of coils passenger vs drivers side, the black wires did the same thing and supposedly they share different common grounds, yet with the nelson harness, they group everything together, so ultimately, they are grounded at the same point.
we'll have to check the passenger side IC wires, we did not test those, just drivers side.
harness is an O3.
guess worse comes to worse, he could get an msd box intended for carb conversions and let it control spark...haha...cause we be gettin fuel. haha Im kidding.
only thing I could come up with, is wiring at the junction box,maybe in the process of grounding and wiring the fans, we connected the wrong damn wire to the wrong damn place...will know for sure later.
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Open circuit voltage describes actual tested voltage found at the "end" of a ground wire that is not connected to ground during testing. It means there is voltage applied to a device then the ground side is measured. If the device is low resistance (or low impdedance) then there would be enough available voltage to light the test light and make the ground "look" like it is powered when in fact it just needs grounded.
Please do not confuse voltage with current.
OK...seven wires. The OEM harness has seven wires to each side in an eight wire connector becuase one cavity is empty.
You would expect that theoretical "ground" wire to have voltage in the test you descibe IF you were testing the ground of a powered component that was not grounded properly.
Does anyone else know what is happening here?
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well the answer to all the confusion.
something is up with the common coil wire.
he bypassed the harness ground, and ground the coils to the block..engine runs.
now we need to figure out where the common coil ground wires go too. inside the harness both banks join and then a single black wire goes toward the underside of the truck...but considering the amount of wire jammed in that harness, it could come back up...haha..
anyone with a schematic for an 03 5.3 truck, have any idea where the coil grounds, ground at?
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I show they tie into G102 which is a common ground to the chasis/block. If you had a 4.3L it would tie back to the PCM through G102 circuit 550 but 4.8L, 5.3L and 6.0L just go to the common ground on the chasis. I wouldn't ground it to the oil level switch.
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I agree, he was guessing the wire went to the oil level sensor, as it headed that direction.
thats what we have g102
so we have two options, trace it and see where it leads or just ground the damn thing to the block.
I have a feeling we need to trace it, as for some reason, the DBW isnt working. it works key on but once the engine fires, it no longer worked, this may be unrelated, only codes will tell, he'll check when he gets off work tonight.
just makes no sense, this wire is a ground with key off but key on, forget it...and that wouldnt be a wire that we would have to connect, shoulda been addressed either at the factory or at the harness company, so no idea why its all screw'd up.
thanks
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I knew you had open circuit voltage.
From memory I was thinking they spliced to one ground circuit and ended up near the ECT sensor at the front of the LH head at G105.
G102 and G103 are at the back of the engine each side. I'd bet NITROUS is correct if he has the information in front of him.
All in all it doesn't really matter as long as the coils are grounded properly now.
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Kinda still matters, Id like to figure out how something so simple, ended up so messed up. :)
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GasGuzzler, G102 and G103 are correct no need to trace them out unless you have time to play with. LSXmyford, I have the diagrams in front of me and that's where the grounds go.
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I think I looked at an '05 or something early on to get the idea about G105...maybe.
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