Dealer Test Mode Displays: "tAc"
WARNING: This page is about a different car, the 2000 Ford Mustang and 1999 Ford Mustang. However, it is still accessible from the selected car via links, so may be relevant.
Displays tachometer data received from PCM through module communication circuit (SCP bus circuit). Tachometer will indicate present engine RPM. Display will shows 0 if engine RPM is zero, input is not received or input received is invalid for one second or more.