1.4.3.1 Monitoring Function

The SOV power stage driver in the TFE continuously and independently monitors for short circuit to ground (SCG) faults (P148B), short circuit to battery (SCVB) faults (P148C), open circuit faults (P148A) and short circuit inside faults (P148D). When any of these faults is detected, the TFE sends a defined code to the ECU and a pending DTC is stored. When a fault is detected in two consecutive driving cycles, the MIL is illuminated. In order to monitor the SOV signal plausibility, the enable conditions listed below need to be fulfilled and only DMTL can execute the tank leak detection monitor.

A SOV stuck open fault (P148E) is detected when the DMTL current does not reach a defined threshold value during the SOV plausibility monitor (reference current - maximum current during SOV plausibility check > 2.5 mA).

A SOV stuck closed fault (P148F) is detected when the maximum current detected during the SOV plausibility monitor does not decrease more than one mA after triggering the SOV (maximum current during SOV plausibility check - current after actuating SOV < 1mA).