Sensor Power Supply Monitor, P1240 - P1242

Sensor power supply monitor P1240 - P1242

High / low input failure
These are continuous monitors. The voltage from the supply is compared to a failure threshold defined in the software. If the voltage is below the low threshold, then a timer starts to increment. Once this timer exceeds another threshold, then a failure flag is set and a DTC is stored. If the voltage is over the high threshold defined in the software, then a timer starts to increment. Once this timer exceeds a threshold, then a failure flag is set and a DTC is stored.

Malfunction
The outputs from two throttle position sensors and one pedal demand sensor are checked. If they ALL fall below a threshold value then a counter is incremented, otherwise the counter is reset to zero. If the counter reaches a calibrated value a failure judgement is made.