Thanks so much for all the replies so far guys. I was wondering why I hadn't seen any replies. Apparently the server isn't emailing me notifications even though I am subscribed to the thread.
My first thought was to use the derale grounding wire to send a ground signal to the wire between the ECM and GM relay. 2 problems, 1 I don't want to damage the ecm, 2 if the GM relay is failing or fails in the future the whole system is dead in the water.
LATECH, do you think you could just quick sketch up the bosch setup you just mentioned? It sounds promising.
Wow yes the original system as it was designed breaks the ground of the Derale system. Do you think you could explain a bit more? That totally sucks if breaking the ground is causing the Derale unit to fail.
I have read a few other forums where people also mention derale controllers failing, and there not cheap! the fact that they redesigned the fan controller had me thinking poor quality. My original controller lasted a few years and failed!