Could be the 'pulse module'.
I sits between the battery and starter and the ignition key tells it to engage the starter. ( you only have to bump the key to the start position, then it takes over )
It is intelligent, in that it will only turn the starter for a specific time ( 5 seconds, I think ) and will disengage the starter when it is told that the engine has started by the PTCM.
( It is actually located in the under hood fuse panel )