TL;DR I have a '92 RS 305 TBI with an ECM connector that doesn't match the pinout diagrams in the factory service manual?

I found this by investigating a "crank but no start" condition. I replaced the plugs, plug wires, ignition coil, cap and rotor (needed it all anyway) but it didn't fix the issue.

Following the troubleshooting steps in my factory service manual, I unplugged the 4 pin connector and the engine started but ran horribly, leading me to replace the pick-up coil. Even after I replaced the pickup coil it didn't work.

Following the rabbit hole further, I probed CKT 430 (reference) on the 4-pin connector to the distributor with a test light which should make the tach jump, but it didn't. So either I had a break in CKT 430 or the ECM was bad.

I went to test the continuity of all of the circuits in the 4-pin connector going to the distributor, and none of the circuits were where the factory service manual said the would be on the ECM connectors. For example:
Circuit 423 (EST), the factory service manual says it should be pin C8 on the ECM connector, but on my connector it is D4 (I checked continuity to that wire). It is the correct color wire and everything just not in the right place.

Will I have to reprogram my new ECM for these pinouts?

 

Just a random thought... Are you looking at the right diagram for TBI and not the tuned port diagram? I've done that, that's why I asked... lol!

 

Honestly that might be it, I'll have a look