Is it true that everytime I disconnect the positive cable from my battery it resets my PCM? If so, would this cause poor GPM?

 

i believe that if u remove the neg cable for 30 seconds that u reset the ecm/pcm and clear any codes that may exist, but will reappear once the computer recognizes all the trucks values again.

 

Definately disconnect the negative rather than the positive just in case there is a spark. A spark on the positive side can blow the computer in 1/10, 000th of a second. Yes that will clear the codes until the computer "re-learns".

 

Are you serious lol? I have always disconnected the positive cable as the way i have always been taught and have heard from professionals. But yes when I disconnected the positive cable I would most always get some sparks connecting and disconnecting it. My truck seems to be working fine though! heh

 

I'm not so sure about the clearing codes thing...IIRCall of the OBD II PCM's will retain them in their non-volitile memory even if the battery is disconnected. I think it will clear the CEL but the codes will still be stored. And Yes you ALWAYS disconnect the NEGATIVE battery cable first....no doubt about that

 

Wouldnt you disconnect the positive first in case you have remote grounds, IE ground from an amp?

 

I have always removed grounds first. Even on earlier non-computer equiped vehicles. Reasoning, I won't shock myself if I touch metal with the wrench while removing the positive terminal. Once the ground is off the battery, no power can flow out of it. No other grounds are active once you break the negative cable free of the battery.