The wrench is the oil change reminder light. It must be reset at every oil change even if the light is not on yet.
ASE Master Tech, L1 Advance Engine Performance certified
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i had the same issue on my 03 cav. i tried throwing parts at it. started with a wheel speed sensor for the abs. turns out it was the wire harness that connects to the sensor. turns out chevy was putting bad harnesses on these cars. hopefully this helps.