P0506: Idle Speed Control System; Dtc: P0506 - Hino Motors HINO 155 series Workshop Manual

DTC: P0506

P0506: Idle speed control system

INFORMATION
1. Technical description
• A difference between a target speed and an actual speed is detected during idling in the engine ECU.
<Description of malfunction>
• A difference between a target speed and an actual speed has been detected during idling.
2. DTC set condition
(1) DTC detection condition
• Starter key "ON".
The conditions described below remain for 10 seconds or longer.
• Accelerator pedal opening = 0% (pedal not depressed)
• Engine coolant temperature is 71 C {159.8 F} or higher.
• The target idling speed is within the range of 745 to 755 r/min.
• Vehicle speed is 0 mile/h.
• The monitor disable DTC table can be referred to.
(2) Judgement criteria
• Actual speed remains at 725 r/min or lower for 15 seconds or longer.
3. Reset condition
• Immediately after normal operation is restored.
4. Indication, warning or system control regulation when the DTC is set.
• MIL: ON
• SVS light: OFF
5. Symptoms on the vehicle when the DTC is set
<Symptoms on the vehicle due to backup control (fail safe function)>
• –
<Symptoms on the vehicle due to malfunction>
• Extremely large load applied to engine while it is idling
• Fuel injection rate abnormality
6. Pre-inspection work
• Perform diagnosis system check to confirm there is no abnormality.
• Check that the battery voltage is in the normal range.
7. After-inspection work
• Clear all past DTCs.
• Check that no DTC is stored after test drive.
8. Estimated failure factors
• Injector injection rate abnormality
• Dragging/interference with transmission
• Failure in air compressor
• Failure in power steering pump
ENGINE (J05E)/TROUBLESHOOTING 2–575
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