After having a bear of a time figuring out why my fan wouldn't kick on, I ended up concluding the computer was inop after replacing all sensors, relays and switches. I ended up just grounding the fan switch for now so I have the fan running while the key is on. My question is, is the ECM the only computer. If I get a Jet performance chip does it replace the ECM? I fugured the cost would probably be less than an OEM ECM anyway.

 

The JET chip is an Eprom, it plugs into the ECM. Picture the ECM much the same as your PC, you have so much RAM and accessories as part of the system. The ECM is basically a computer in the most simplistic terms and the Eprom determines the personality of the vehicle-options, type of injection etc. Operating information for that specific engine is contained within the prom. Aftermarket proms are not really worth the money, all they do is advance timing more aggressively. TG ECM's are not nearly as close to complexity as are the current generation of PCM's. It's your money spend it as you choose, but the gain per dollar is almost non existent. A decent exhaust system, maybe a K&n air filter will probably do as much as any chip change.