[parsonsj]

After a considerable amount of debugging, testing components, and general frustration and angst... I called GM Powertrain today.

Here's why: my system doesn't work. I can get discrete fans to work, no problem. But not a PWM fan. I've tested all the components individually and together. I built test harnesses and even sent my fan controllers off to be individually tested by a small company in Wisconsin.

All work fine.

Today, I got the GMPP help number and talked with tech support. They tell me that the fan PWM circuit is disabled in the GMPP crate motor ECMs in an effort to simplify tech support and reduce warranty claims.

So: you guys with GMPP crate motor E67s... how did you get your PWM fans to work?