Anyway, here's what I found out looking into ECM's / PCM's for Jeep TJ's.
It appears that somewhere between 75 and 95% of what is wrong with a TJ's ECM, when it goes bad, is NOT the components on the circuit boards, or the circuit boards themselves. The programming is burned into the ROM, and is not something that can be modified. So, if the program can't be changed or rarely becomes corrupted, and the hardware is very reliable, what does that leave us with?
The connections and solder joints in the ECM. Yup, most of the issues we are likely to experience with our ECM's boils down to failed solder joints and dirty connections.
Surprisingly enough, a trip to the internet and Radio Shack can let you fix an ECM in most cases. This may be a good thing. MOPAR doesn't have new ECM's available, and will charge you a boat load of money for a rebuilt one. Guess what? MOPAR gets them rebuilt at the same places you and I can. A couple of things about repaired / rebuilt / re-manufactured ECM's. There is a difference between a $170 ECM and a $500 ECM. It takes time to clean and re-solder all of the connections, remove the potting compound and repot the boards, & etc. Time equals money. Also, make sure that the ECM is programmed with your serial number and mileage. The dealership can do this, but will charge something along the lines of $120.
If you have soldering skills, all you need is a 15 watt soldering iron, fine rosin core 40 - 60 solder, a solder sucker, contact cleaning chemical, something to clean potting compound from the boards and clip on heat sinks.
More later as I dig up photos and such.
Oh, I'm having mine rebuilt professionally. No soldering skills.
