No start problem

Bye 87GN

On life support
Joined
May 25, 2001
No start condition, 87 GN

I followed the GM no start flow chart line by line.

ignition on - SES light should be on. SES light is NOT on, so I check power at ECM, power on C16 so I presume that my SES light is burned out.

connect noid light to injector - flashes when turning over indicates cam and crank sensor OK.

fuel pressure at rail, (plugs are wet with fuel upon inspection so fuel does not seem to be the problem). Disconnect injector connector

check spark at cylinders 1, 3, 5 - 1 has no spark, 3 has spark, 5, has no spark

verify plug wire resistance less than 30K ohms, 1 and 5 check OK. Just for the heck of it I check no. 1 plug in wire for 3 since it had spark, to rule out plugs in 1 and 5 going bad at the same time (not on the flowchart). No. 1 plug fires ok on no. 3 wire.

remove 6 coil pack screws and separate from module

disconnect affected coil's control wire from coil, connect test light between the common feed (blue wire) and the control wire. I used yellow/black for coil pair 1/4.

Does test light blink while cranking - yes

Flow chart complete --> faulty coil or connection to coil.

OK, so the module is OK but the coil is bad. So here's my question. Before I started all of this, I snagged at module/coil from a GN that runs fine. I swapped them out. With the suposedly "bad" module/coil assembly the GN that was running OK, still runs OK. With the "good" module/coil assembly the GN that was NOT running, still no start.

I'll swap in a new coil tomorrow as the flowchart says, but why wouldn't it start with the known good module/coil assembly, and why would the other GN run with the "bad" module/coil assembly? I'll bet with the brand new coil, it still won't run. Anything I missed?

Is there any way that the SES light being out means something? Doesn't the fuel injector test light blinking and having spark in at least one cylinder mean that the ECM is OK?

Any suggestions are appreciated.
 
Exactly as I thought, I replaced the coil and same deal. No spark on 1 or 5. The problem has to be somewhere else, but where?

Checking the SES light next.
 
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