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Showing results for tags '12 volt'.
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I have a 98 Silverado z71 with 5.7 350. The check engine light came on giving p0405 code. (low egr voltage). I have replaced the egr and nothing changed. I tested the wiring with the egr unplugged and it tests fine, but if I plug the egr in I lose the 12 volts. If I unplug it I have 12 volt. Now that's with my ohm meter. If I put a load on it, ie hook a headlight to it, it wont power it. I have traced all of the wires back to the ecm. They all are fine. I even unplugged the wiring from ecm and put 12volts from the battery thru the 12volt wire going to the egr and the wire is fine. A friend who is a mechanic by trade said it could be the ecm. I replaced the ecm today.(not a brand new one. one from a used parts/salvage yard). I got the truck to run and the check engine light came on within a few minutes. Same as before, with the ohm meter I have 12 volts going to the egr with the plug unplugged, as soon as I plug it in it goes to 0.03 volts. I even bought another egr thinking it could possible be a bad/shorted one. I'm at a total loss. any help would be great. Thank you!!