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Hi all, I'm sitting here and wits end. Tranny went out on the envoy so got a new one and installed it. Put a new nuetral safety back up switch. It started ran great took for a test drive ev er everything was fine. Said to my wife here take it for a spin im sure you forgot what 2nd gear was like. She got in went to put into gear it died, would only crank over and over wouldn't start back up. So made some calls to a couple of master techs I know ( ofcourse they live in different states so cant come and help directly) for any advice. They all came to the conclusion that fuel pump went out, so with much reluctance i dropped tank and switched pump. And also i hooked pumps up directly to battery both old and new work flawlessly. So now it has a new tranny and fuel pump but no juice to pump. So next suggestion was ignition switch, well needless to say has a new ignition switch also. So I thought well dang maybe the nuetral safety switch was bad from manufacturer , nope has another new nuetral safety switch. It would just crank and crank no start. I got another preprogrammed CPU installed now it has a new CPU. Then I noticed that pcm 1 fuse was blown replaced, still nothing and fuse isnt blowing anymore. And now I have no cluster lights except for battery and gear shift indicator eliminates but is locked in park. Also the power windows dont work but yet blower fan and hazards and light come on.( but not with key but with switch on dash.also I lost all power to ignition. if I jump starter relay it turns over good if I shoot a little starting fluid into throttle body it will almost catch and start, I followed harness from CPU to fuel pump can't find any broken wires and every ground I found is in great shape. Over the last 2 years everything on this vehicle besides pistons rod and main bearings has been replaced she loves this truck more than me. Lol. Looking for any help on something I might have missed or has had this situation before. Oh yeah and to add I'm nothing getting power to back half of fuse box except for starter relay, pcm #28 fuse isnt getting power anymore. Thanks to all that can help.
 

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2000 Silverado Z71 4x4 5.3L 460k+ miles w/ GM rebuilt motor and trans
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There's a lot to process here and I think some things are being caused as you go. Take a minute and press pause on the tinkering.

First off, did you verify you had a functioning fuel pump relay? Just had one go out on me right after I did some work under the hood, so it looked like a different problem.
 

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Check for melted wires or corrosion at and under the fuse block by the engine. Even check the contacts, at the dealership I work at we have seen several vehicles have issues similar to this. (I just work in parts). Most of the time it came down to either a bad ground or the main fuse block was junk underneath. There is also a plug behind the small fuse panel in the door jamb area on the driver side. I believe it goes to the back of fuse panel there and some relays. I think the plugs are square in shape and have to be accessed behind the panel. Make sure those are good and that they are plugged in fully. One or two of the relays there do have some control over starting and electronics. My friends 03' truck had an almost identical problem and it was a junk relay in that block that was causing it.


Just something to check if you haven't already
 
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