On Sunday I loaded a new file on my PCM, then went to read PCM just to make sure it took ok. However when trying to read the PCM it told me there was no connection, so I turned the key to the off position, then back to the On pos. and I didnt here the pump prime or anything. I tried to start the car and the engine just turned but wouldnt fire. I thought the PCM was fried, so I decided to disconnect the battery for a few seconds, then tried and it was working again . Is this an indicator that the PCM is on the way out, or something that commonly can happen when reprogramming? My cable was crimped a bit in the door and Im wondering if the connection could have been messed up from that as well, cause I moved the cable and it was working fine.

 

Failure during reading will render the car inoperable, but a reset of the PCM (whether it's done through the fuse, battery or other means) will return things back to normal.