pcmhacking.net

Ignition module takes the reluctor signal, coil and power and converts it to the common delco 4 wire interface. On the input there is reference high and low (the reluctor coil), which can be hooked backwards in which case you get poor performance and bad timing so keep that in mind when you first fire it up - could be a fault. On one other side of the module it drives the coil. Then there is a logic on or off signal from the computer (called BYPASS) which is used when cranking before the computer has sync, and in this mode the ignition module generates a static 10 degrees spark to get the engine up to speed (this speed is in the tune, defaults to 400 rpm). If you unplug the 4 wire connector from the module but leave the others connected you'll keep getting spark at 10 degrees in module mode. This is a good test of the electrical system taking the computer out of the picture, and can also be used to set base timing (or there is a diag signal wire going in to the computer which you can use to get static 10 degrees with the computer in control). The ignition modules also converts the analog reluctor signal to a 5 volt square wave and sends it through to the delco as this is what it expects. The distributor rotor sends the spark to the right cylinder - the computer doesnt actually know which cylinder is going to go bang, and doesnt need to know for MPI or TBI ignition.

You might have seen this but it puts some pictures around what were talking about:
viewtopic.php?f=15&t=4&p=4#p4

Great explanation. I my simple terms is if your distributor had an inductive (coil of wire and magnet with 2 wires) trigger yes it will work. Hall effect 3 wire triggers are different and yes the polarity of the inductive coil must be correct but you will soon find that out with big misfires. It's then a simple fix of swapping the 2 wires from the pickup coil.

Iac map and ignition module

Hello Delco,

If yo PM me with your Bank acc and costs ...I will send you $'s

robbie