Test Electrohydraulic shut-off device EHAB Flash code: 3x long, 1x short Fault indication: Fault indicated by steady light at EDC indicator lamp Fault path: EHAB function Effect of fault: Engine is shut down Engine will not start (in this case, it is assumed that the fuel supply is OK) Reduced full load delivery volume Reduced final engine speed n = 2000–2100 rpm Function: The EHAB performs an important safety function in its capacity as an independent, higher-ranking (redundant) engine shut-off device. The EHAB is activated in certain emergency situations when the engine can no longer be shut off by controlling fuel delivery to zero – e.g. control rod jammed.
The EHAB reduces the pressure in the suction chamber of the injection pump thus interrupting filling. Possible cause Line break, relay K2 defective, short-circuit, EHAB defective, faulty activation from control unit (control unit defective) Test precondition: EDC control unit connected Socket box connected Note: Power must be applied to the EHAB when bleeding the fuel system by means of presup- ply pump, i.e. the fuel system cannot be bled without the “ignition” being switched on! See page 31 for function test.
58 Test Measurement Corrective measures Coil resistance “Ignition” switched off Control unit disconnected Measure resistance at socket box across a) Pin 14 and Pin 24 (Relay K2) Setpoint: 30–70 Ω b) Pin 19 and Pin 21 (Relay K2) Setpoint: [0 Ω – Check line – Check plug connection – Replace EHAB Check relay K2 See Page 55 See Page 55 Power supply Turn on “ignition” Measure voltage at socket box across pin 14 (+) and pin 19 (–) Setpoint: U-Batt – Check line – Check plug connection – Replace EHAB If no fault is found: – Replace control unit