Description
The electronic throttle control system (etcs) controls the engine idling speed. The etcs operates the throttle actuator to open and close the throttle valve, and adjusts the intake air amount to achieve the target idling speed.
In addition, the ecm retards the ignition timing and the etcs increases the intake air amount to quickly increase the catalyst temperature at cold start to reduce emissions.
Monitor description
The ecm monitors the intake air amount during idling and the ignition timing.
When the engine coolant temperature (ect) is between -10°c and 50 °c (14°f and 122°f), the ecm calculates the idling intake air amount for 10 seconds, beginning 3 seconds after the engine starts.
When the accumulated value is below the threshold, the ecm interprets this as a malfunction in the idle speed control (isc) system at cold start.
The ecm also monitors the ignition timing at cold start, and judges it to be incorrect when it is advanced to the same value for a warm engine for 5 seconds or more of the 10 second monitoring period.
Example:
P050a is detected when all conditions below are met (2 trip detection logic).
The ecm sets the dtc and illuminates the mil 13 seconds after the engine is next started.
Notice:
When the negative battery terminal is disconnected during inspection or repairs, the isc learning values are cleared. The isc learning must be performed by warming up the engine and idling for 5 minutes with the ect at 75°c (167°f) or more because dtcs cannot be detected with the isc learning values cleared.
Monitor strategy
Typical enabling conditions
Typical malfunction thresholds
Inspection procedure
Hint:
Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.
Hint:
If any dtcs other than p050a and p050b are output, troubleshoot those dtcs first.
Hint:
Calculate the total fuel trim values to check the characteristic deviation of the mass air flow meter.
Ok: total of short ft #1 and long ft #1 values is between -20 % and 20 %.
Ok: pcv hose is connected correctly and is not damaged.
Ok: air cleaner filter element is not excessively contaminated with dirt or oil.
Go to step 15
Go to step 15
Go to step 15
Go to step 15
Go to step 15
Ok: no deposits around throttle valve and throttle valve moves smoothly.
Go to step 15
Go to step 15
Notice:
In this operation, the engine must be cold (the same level as the engine coolant temperature recorded in the freeze frame data).
Ok: stable fast idling.
Ok: no dtc output.
Front occupant classification sensor rh circuit malfunction
Description
The front occupant classification sensor rh circuit consists of the occupant
classification ecu and the
front occupant classification sensor rh.
Dtc b1781 is recorded when a malfunction is detected in the front occupant
classification sensor rh
circuit.
Wiring diagram
...
Engine control system malfunction
Description
If a malfunction in the engine control system is detected, the operations of
vsc and trc are prohibited
by the fail-safe function. When the signals from the engine are input normally,
the fail-safe is canceled and
the dtc is not stored.
Inspection procedure
Check harn ...
Occupant classification sensor power supply circuit malfunction
Description
The occupant classification sensor power supply circuit consists of the
occupant classification ecu and
the occupant classification sensors.
Dtc b1793 is recorded when a malfunction is detected in the occupant
classification sensor power
supply circuit.
Wiring diagram
...