Fail-safe Function
Purpose of the fail-safe function
If the ECU detects a malfunction in any of the input signal systems, the fail-safe function controls the engine using standard values contained in the engine ECU, or stops the engine to prevent engine problems or catalytic overheating which might occur if control continued based on the circuitry with abnormal signals. The relationship between circuitry with abnormal signals and the fail-safe function is shown in the table below.
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Circuitry with abnormal signals |
Signal name |
Fail-safe function |
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Ignition confirmation signal circuitry |
IGF |
Fuel injection is stopped. |
|
Manifold pressure sensor signal circuitry |
PIM |
The fuel injection duration and the ignition timing are fixed or calculating by the VTA throttle opening and engine speed. |
|
Air flow meter signal circuitry |
VG |
The fuel injection duration and the ignition timing are fixed or calculating by the VTA throttle opening and engine speed. |
|
Throttle position sensor signal circuitry |
VTA |
Control at the standard value. (Valve opening angle : 0 or 25…) |
|
Water temperature sensor signal circuitry |
THW |
Control at the standard value. (Coolant temperature : 80…C) |
|
Intake air temperature sensor signal circuitry |
THA |
Control at the standard value. (Intake air temperature : 20…C) |
|
Knock sensor signal circuitry |
KNK |
The corrective retard angle is set to the maximum value. |