Stupid Mechanics...It makes those that know something work three times as hard to gain motorists trust.
If your injectors really are not pulsing:
I am lazy. Had I swapped out the distributor and had no injector pulse I would plug my scan tool into it. If my scan gives me data and I see no engine RPM, I would be replacing the ignition control module. I would have not screwed up the connections though. Your mechanic's results might vary...:roll:
The correct diagnostic strategy, not leaving anything to chance if you don't hear injectors clicking: (If you want to skip the first paragraph because you KNOW that you didn't do anything to distrupt power to the PCM you could skip right to the XXX paragraph below and just check for the 1-2 V signal , substituting the the 4 pin connector (PIN C / Purple/White) at the distributor. If you have spark, but no injector pulse, you can go ahead and put your QUALITY replacement module in and skip all these nifty steps):
At the PCM pins C12 (Green) and C11 (Blue) check to see if battery voltage (B+) is present with the Key-On. If there is no voltage present, then you have an open circuit (harness disconnected) or blown fuse (ECM) or some other variation of weirdness that doesn't allow voltage to migrate to the injector drivers through the injector circuit. You can also verify A6 (Pink/Black) has power as it comes from the same fuse, but prior to the injectors.
If B+ is present,then crank it over. With a test light on the C12 or C11 pins at the PCM (and the other end of the test light on a GOOD ground), you should get a flashing light as you crank it, each time the light shuts off would indicate the injector driver is turning the injectors ON. If you have a flashing light, then their diagnosis is bunk and look towards fuel pressure. Of course, that doesn't mean the injectors are mechanically opening (like they suddenly had 100psi feed pressure preventing the seats from opening).
If the test light doesn't flash, then the PCM isn't getting something it needs. To convince the injectors to open doesn't take much:
Powers at the PCM:
B1 and C16, these always have B+
A6, B+ with ignition on
Grounds at the PCM:
A12 (Black/White)
D1 (Tan/White)
Definitely D7 and C13, as these are the injector grounds (Black/White)
XXX Then verify C7 or D8 (the Purple/White wire) has a square wave. With a meter, it will be a small voltage, probably around 1-2V, although a scope would show a proper signal, with proper amplitude at both signal high and signal low. This is the signal that has the injector drivers closing, allowing current to flow and resulting in injectors opening. No voltage here and there is a pick-up coil or ignition module problem (if the coil isn't firing) or an ignition control module problem if it is. The control module will fire the coils and not send a signal to the PCM to fire the injectors if it is bad. You can test this by applying a 5V signal (tap it off the MAP sensor) to the Tan/Black bypass line. This would put the module into EST mode (computer controlled spark). If you loose spark, you likely don't have a reference signal from the ignition control module on the C7 or D8 (Purple/White) wire. For the record, my notes show both of these connectors being Purple/White, but only 1 is correct)
With those few things, you will have an injector pulse. If you don't you have a bad PCM, or like someone else found out on the board, the wiring to the PCM was changed. Now add proper fuel pressure and proper timing of the spark that is allegedly there and it will start.
For the record, this is typical of GM. The syclone PCM strategy isn't different than the millions of fuel injected GM cars and trucks out there. If they can't figure the Syclone out, they couldn't figure out a cavalier or full size pickup no start either!
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