On 6/21/2012 8:27 PM, neil n wrote:

> Would shunting in an LED in parallel complete the circuit so ECU thinks the
> throttle valve switch was closed 100% of the time?

Probably not. The ECU was designed to expect the voltage to go very
close to 0 when the switch closes. There's probably a simple bipolar
transistor input to sense that, which would toggle at about 0.7 V (the
typical threshold for a silicon junction). A red LED has a typical
forward voltage drop of around 2.1 V (other colors usually higher). It
won't pull any current unless the voltage is higher than that, so it
wouldn't pull the signal down enough to signal the ECU.