Test Speed sensor Flash code: 4x short Fault indication: Fault indicated by steady light at EDC indicator lamp Fault path: RPM sensor Statically implausible Dynamically implausible Implausible with auxiliary rpm sensor Effect of fault: Reduced full load delivery volume Reduced final engine speed n = 2000–2100 rpm If the auxiliary rpm sensor also fails, the engine will be shut down by EHAB Possible cause: Line break, short to ground, rpm sensor defective, control unit defective Test precondition:
Disconnect EDC control unit to ensure the engine cannot start up Socket box connected U > 2 V 41 Test Measurement Corrective measures Resistance Measure resistance at socket box across pin 21 and pin 13 Setpoint: 800–1000 Ω – Check lines – Check plug connections – If no fault found, replace rpm sensor Engine speed sig- nal Check signal at socket box at start- ing speed across pin 21 (+) and pin 13 (–) with oscilloscope Setpoint: See figure