13-44
P1254: PRV Opening (warning lamp flashes: 36)
P1255: Common Rail Pressure M/V 1 (warning lamp flashes: 63)
Generation condition
Diagnosis code is generated under either of the following conditions
• Common rail pressure is abnormally large.
(except forced opening of pressure limiting valve by electronic control unit
control)
• Pressure limiting valve is faulty.
(Limiting valve opens even though the common rail pressure is normal.)
• Abnormal common rail pressure due to leakage or clogging of fuel system
Recoverability
System recovers (power is re-supplied to electronic control unit) if signal becomes
normal when starter switch is turned OFF (2 minutes or more) → ON.
Control effected by electronic control unit
• Injection quantity is limited. (Output is reduced, and exhaust emissions wors-
en.)
• Exhaust gas recirculation control is stopped.
• Auto cruise control is stopped.
Inspection
Service data 0C: Difference Common Rail Pressure
Actuator test B9: Fuel Leak Check
Electronic control unit connector : MPROP (rail pressure control valve)
Electrical equipment #574: MPROP (rail pressure control valve)
Electric circuit diagram MPROP (rail pressure control valve) system
Other
• Air-bleeding of fuel system (See “ON-VEHICLE INSPECTION AND ADJUST-
MENT”.)
• Inspection of fuel piping (See “COMMON RAIL”.)
• Fuel filter (See “FUEL FILTER”.)
• Gauze filter (See “ON-VEHICLE INSPECTION AND ADJUSTMENT”.)
• Supply pump (Have work performed by Bosch.)
• Pressure limiting valve (Have work performed by Bosch.)
• Injectors (Have work performed by Bosch.)
Generation condition
MPROP1 (rail pressure control valve) circuit shorted to ground or open-circuited
(low level when turned OFF) as detected for 0.3 second.
Recoverability
System recovers (power is re-supplied to electronic control unit) if signal becomes
normal when starter switch is turned OFF (2 minutes or more) → ON.
Control effected by electronic control unit
• Injection quantity is limited. (Output is reduced, and exhaust emissions wors-
en.)
• Exhaust gas recirculation control is stopped.
• Auto cruise control is stopped.
Inspection
Actuator test B9: Fuel Leak Check
Electronic control unit connector : MPROP1 (rail pressure control valve)
Electrical equipment #574: MPROP1 (rail pressure control valve)
Electric circuit diagram MPROP1 (rail pressure control valve) system
14
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TROUBLESHOOTING <DIAGNOSIS USING Multi-Use Tester>
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