94 LT1/4l60e transplant into a 95Z body.
It was a compete drop-out using the 94 PCM & engine harness. The 95 body has the 3 relay config.
The fans run when I short pin 5 & 6 with key on, on the DLC.

Problem is, the fans will not run when the temp reachs 226 degrees monitored using Datamaster.
Using Tunercat, I can see the fan 1 & 2 ON threshold, low & hi mph are set stock, to 108 & 133 respectivley.

Are there any other "ECM constants" that would keep my fans from running when these temp values are reached?

 

Do you see the fan relay flags change in Datamaster?

 

Unfortuanatley, I was in monitor mode and didn't know to look for the flag.
Now I've found it and recorded a session...don't know if this is good or bad...they're working.

I started recording once the temp came up, and sure enough, once over 108, I saw the flag go red, and the fans started. I watched it cycle 3 times...worked perfect.

I hate intermittent problems.

Thanks for the direction Shoebox