My s-10 with the (0411 swap) was one of the 2 PCM's I had problems with also...:D
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My s-10 with the (0411 swap) was one of the 2 PCM's I had problems with also...:D
To add to this thread, I have a 99 c1500 pcm that I upgraded to the "156" OS (and eventually cos5) and had this problem. I Left the terminal assignments the way the 99 stock gm calibration had them and changed the dtc p1638 to "not reported". So far so good. Apparently the 02 type pcm has an extra wire running to the alternator that it uses to calculate duty cycle (paraphrasing info I read yesterday). This 99 pcm doesnt have the wire and therefore can't sense the alternator so the killing the code is no problem. I believe from reading that if you want to run an 02 PCM in a 99 truck you need to run this wire (or maybe you can also set this to not reported to stop the code?) I am not sure. Cheers!
See the thread below for wiring information ...
http://forum.efilive.com/showthread....l=1#post151751
Regards,
Taz