The diagnostic value of the scope
There was a time in my career when replacing a computer was touch and go. I always tried to do my due diligence and eliminate everything else as a possible cause before replacing the computer, but sometimes that wasn’t enough, and I would miss something along the way. That was long before I learned how
Walt’s ’57 ECM Woes
“Drive by wire,” if you’re not familiar, is a system of throttle control using a set of accelerator-pedal-position (APP) sensors to tell the engine-control module (ECM) what the driver would like to have happen with the throttle. The ECM uses a throttle-actuator control (TAC) module, which opens and closes the throttle plate to the desired angle. The TAC module contains a set of throttle-position sensors that operate linearly opposite each other the same way as the APP sensors. Contained inside the TAC module is also an actuator that is driven by the ECM that moves the throttle plate itself.
