ECM1 burned... causes?

[Xenon]

I'm getting everything together to put TBI back on my '87 Subby... I've been thinking about what you guys said that maybe my ECM wasn't bad after all. I've thought of many explanations, but the thing I still can't explain is that when it finally died the ECM1 fuse was blown. I replaced it, the truck was still dead but it didn't blow again.

What kinds of things could make ECM1 blow?

I've been reading on this forum almost every day and have learned ALOT. Thanks for all the help.

[PJG1173]

I would get the wiring diagram for your truck and back trace what circuits are hangin off of that fuse.

[EagleMark]

There's wiring diagrams for the ECM in the 1227747 $42 thread. But I don't know what ECM1 fuse in truck powers? It could power ECM and when ECM went bad fried fuse? Now you replaced fuse and there's nothing left in ECM to pop it again? Or could be power to EGR and sensors or injectors? There's lots of power to circuts then to ECM for ground or reading. Have to look at truck wiring and see what that fuse powers.

[RobertISaar]

looking at a 87 suburban 3/4 ton 4WD with 5.7 diagrams...

the fuse that the ECM uses for ignition on signal also powers the EGR/EVRV solenoid, the EAC solenoid and the ESC module.

it might power more.

[Xenon]

Thanks. Will looks at the wiring and see what I find.