could someone please explain what limp mode is to me?
i saw it in another post and was wondering if someone could explain it to me

 

There are actually two failure modes for a GM ecm.
But, folks tend to lump them together. Anyway,

1. Limp Home Mode,
Is when there is a processor failure, and the ecm just runs on the redundant fuel devise, and the ignition advance in the ignition module. It's designed to just get you home. In case of a huge failure, there might not be a check engine light.

2. Fail Soft Mode,
Is when there is/are sensor failures, and the ecm uses some default values instead of the bad values, and lets you drive home with the check engine light on.

 

I never realized there were 2 different modes. I just recalled the time my dad screwed up his TA.. well some mechanic did and while driving went into this crappy mode spitting out rich exhaust and barely moving. GM tech explained to us that it was a limp mode and since his entire sensor system shorted, the ECM backed off into it. I had no clue though that the other mode existed if the ECM itself went out.