Here is what is gathered so far. 97 blazer 4x4 4.3 no spark.no power to icm or coil...


Ignition coil:

Terminal A, PNK wire, ignition voltage, from 20A ECM/Ign fuse 10 in I/P fuse block
Terminal B, WHT wire, tach sig, to IPC terminal 8
Terminal C, WHT/BLK wire, tach sig, from ICM terminal D

ICM:

Terminal A, PNK wire, ignition voltage, from 20A ECM/Ign fuse 10 in I/P fuse block
Terminal B, WHT wire, ignition timing sig, from VCM connector C3, terminal 9
Terminal C, BLK/WHT wire, ground
Terminal D, WHT/BLK wire, tach sig, to ignition coil terminal C

Upstream of the ECM/Ign fuse is the ignition switch and then one of the fusible links.

Ignition coil:

Terminal A, PNK wire, ignition voltage, from 15A ECM1 fuse in underhood fuse block
Terminal C, WHT/BLK wire, tach sig, from ICM terminal D

ICM:

Terminal A, PNK wire, ignition voltage, from 15A ECM1 fuse in underhood fuse block
Terminal B, WHT wire, ignition timing sig, from VCM connector C3, terminal 9
Terminal C, BLK/WHT wire, ground
Terminal D, WHT/BLK wire, tach sig, to ignition coil terminal C


One says its under the hood in the fuse block the other says in the truck. Where is the fuse block under the hood? And all the fuses in the truck checked out. I need to trace it all the way back im guessing it could either be a bad wire, fuse,ecm or ignition switch. is this a common problem on these trucks what would you guys think it is?