Accelerator Pedal Sensor (PWG)
The driver's application of the accelerator pedal is monitored by a PWG sensor in the driver's footwell as with previous non-bowden cable EML systems.
The PWG provides two separate variable voltage signals to the ME 7.2 control module for determining the request for operating the Electric Throttle Valve (EDK) as well as providing a kickdown request with automatic transmission vehicles.
The ME 7.2 monitors the changing signal ranges of both circuits as the pedal is pressed from LL to VL.
- In vehicles equipped with an automatic transmission (A5S 440Z), the ME 7.2 recognizes the max pedal value (4.5V) as a kickdown request and signals the AGS via CAN bus.
PWG SIGNAL MONITORING & PWG FAILSAFE OPERATION:
- If the monitored PWG potentiometer signals are not plausible, ME 7.2 will only use the lower of the two signals as the driver's pedal request input providing failsafe operation. Throttle response will be slower and maximum throttle position will be reduced.
- When in PWG failsafe operation, ME 7.2 sets the EDK throttle plate and injection time to idle (LL) whenever the brake pedal is depressed.
- When the system is in PWG failsafe operation, the instrument cluster matrix display will post "Engine Emergency Program" and PWG specific fault(s) will be stored in memory.