1996 GMC 3500 SAVANA Van 5.7L Vortec Auto Trans 2WD. Crank, No Start, No Spark

wrote:

Those pink wires power all the sensors. Could he just unplug one at a time and when voltage jumps to 11.4 he found the resistance?

the voltage drop is rearing its ugly head during crank only
"Ignition voltage," hmmm. Don't tell me this is another bad ignition switch lol

wrote:

Looking at this info.: { troubleshootmyvehicle.com/gm/4.3L-5.0L-5...uts-1996-1997-page-3 }
C3 Grey (Is Grey equal to my White??) connector pin #21, orange wire is 12V battery feed.  Is this wire feeding 12V from the fuse block into the ECM?

Yes that's a hot at all times from underhood fuseblock. Is this voltage dropping there too?

I should have been specific. I ment while he is cranking.

I went back checked voltage drop with one lead at battery positive and the other on a Tee pin at pink ignition feed wire, blue connector pin 4.  The meter was between 0.0 and 0.2 and 0.3..  The Tee pin originally may have not been making a good connection.  I am sorry for that misinfo.

He's says he's getting low voltage at the ignition 1 voltage and at the coil, and the power feed splices off here, so I think the problems up here north of this diagram, lol.

 

So now you have a steady 12v on the pink wire at c1 pin 4 while cranking with .02 drop. 12v on pink wire at coil, pulse on wht/bk and spark at coil wire.

So here's a story.  My wife has a business that does custom flowers for weddings.  She needed a van to haul flowers to venues and breakdown afterwards.  Not needing a new van, I started looking for a used one.  This van was used by a local tire shop.  It was and had been sitting at their shop for years, they said two but the last registration card was seven years old.  Everything looked original, rust free, never wreaked, and dry/no leaks.  So for $600 I have a challenge.  They told me "two" years ago the van was going down the road and just shut off.  That's about all I knew.  Fuel, fire and air all happening at the right time.  I had fuel and air but got frustrated with the electrical part.  After taking in your advice I slowed down and started going one step at a time.  I was concerned the ECM was faulty.  And also a problem in the wiring harness. 
I went back and verified good 12V out of ECM while cranking.
I measured a 7V drop between ECM and coil feed/pink wire.  So I run a direct wire from ECM ignition/pink to coil.  No voltage drop.
Then I had no power to ICM. 
I went back to the ECM pink and with a butt connector, wire out of ECM on one end of butt and twisted downstream pink from ECM and dedicated new wire to coil together on the other end of butt connector.  That 12V pink feeds alot of other components,
So now I have 12v to ICM during cranking.
At that point the crank turned into a start.
The engine is quiet, good oil pressure, cooling system good so far, the trans shifts good, steers and stops.
I now will tidy up wiring, seal and secure, address A/C and alot of cleaning.

This is the first time I have engaged on a forum.  Thanks to Scanner Danner and the forum members who offered advice.
Mitch

  

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