My engine has been running hot, and I'm sure that my fans have been coming on, at least with the fan switch in the pass. head. I didn't know if my coolant temp sensor was bad, or my guage reading was off, so I hooked up my laptop to the aldl connector to see what my ecm was seeing.The CTS seems to be working fine, and my temp guage is reading a little high, but not overly so. But the main fan never comes on. At 109.3c (according to the software I was using to monitor the ecm), both fans click on. At around 102c, they turn off again. My understanding is that the driver's side fan should come on by itself at 106c, and off at 104. If the secondary fan comes on via the head switch, are both fans supposed to come on? Does anyone have an idea why the ecm isn't turining on the singe fan? It's a burned PROM, but I didn't change anything except the flag for manual tranny. The software on my laptop doesn't show the ecm requesting fan1 until they both turn on. IIt's a downloaded BIN, but I checked the fan settings, and they look stock to me. Anyone have any ideas what is going on here?