I have a 92 bonneville that won't start after runnung for a while. It just turns over and over and won't fire up there is no spark while turning over either. i am getting a 17 code and a 21 code. It should still fire up with the 17 code but the other one maybe not. i believe the 21 code is spark reference circiut is it not?? Could this either be icm or the pcm. Thanks for your interest..

Thanks, Dan

Sounds like it is the crank position sensor. It gets the spark reference from a ring on the harmonic balance. Check the connection down by the crank pulley.

O.k> i will give that a try . when i was outside last night and trying to start it while it was hot and thought to grab the air gun and put some air under the icm and blew some air on the crank sensor as well, and i don't know if was just the time when it kicked back in or not but it started right up . I'm going to start it up again and try it again on each. the crank sensor first and if that doesn't on the icm.