3-30 ENGINE CONTROL SYSTEM
FAIL-SAFE SYSTEM
The fail-safe system is closely related to the self-diagnostic system.
When an abnormality occurs in a sensor signal, the ECM ignores the out-of-range signal and assumes a pre-
programmed value for the failed sensors.
This allows the engine to continue running under the fail-safe condition.
PRE-PROGRAMMED VALUE FOR FAIL-SAFE SYSTEM
NOTE:
There is no back-up system for the ECM itself. The engine will stop if it has failed.
NOTE 1:
This value will change according to the current engine speed.
FAILED ITEM PRE-PROGRAMMED VALUE
MAP sensor 1
CKP sensor
Based on signals from CMP sensor :
• Ignition timing fixed at BTDC 5°
• Normal sequential fuel injection
• 319 – 475 mmHg / (Correspond to approx. 750 – 4000 r/min.)
[NOTE 1]
CMP sensor
Based on signals from CKP sensor :
(a) Failed while engine running
• Ignition timing fixed at BTDC 5°
• Normal sequential fuel injection
(b) Failed prior to engine start
• Ignition timing fixed at BTDC 5°
• 1 simultaneous injection for all cylinders per 2 crankshaft rotations
Cylinder temp. sensor
IAT sensor
Exhaust manifold temp.
sensor
60 °C (140 °F)
45 °C (113 °F)
60 °C (140 °F)
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