Just wondering if the chip controls the grounding to instruct the cooling fan to come on or if it is another portion of the ECM. I know the temp you want it to start up is controlled by the chip. I have checked out all the wiring as far as I can tell and the cooling fan does not start when needed and points to the ECM. I have bought a new chip from turbo tweak but that did not help. I have hooked up a ground wire to the low speed relay for now to start the fan. Let me know if the ECM itself has control of anything or any other info that you might see that could be the problem. Thanks.