Fail-Safe System Description
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 preprogrammed value for the failed sensors.
This allows the engine to continue running under the fail-safe condition.
Pre-Programmed Value for Fail-Safe System
| Failed item | Pre-Programmed value |
|---|---|
| MAP sensor 1 | • 240 – 760 mmHg /(9.4 – 30 inHg.) (The control takes place in accordance with the engine speed.) • VVT advance is fixed at the most retarded angle. |
| Air intake system | • The control is executed with the maximum engine speed as 2 000 r/min. |
| Cylinder temp. sensor | 60 °C (140 °F) |
| IAT sensor | 45 °C (113 °F) |
| Exhaust manifold temp. sensor | 60 °C (140 °F) |
| Throttle position sensor | • The throttle opening is fixed to default with the throttle motor relay turned off. ECM controls the engine speed at the maximum of 2 000 r/min by operating the remote control lever. |
| Shift position sensor | • ECM detects the shift position as neutral even under in-gear condition and controls the engine speed to idling. • If the “Throttle only” button is pressed with the remote control lever in neutral, the engine speed can be controlled at the maximum of 2 000 r/min by operating the lever |
| CMP sensor (VVT) | • VVT advance is fixed at the most retarded angle. |
| VVT advance | • VVT advance is fixed at the most retarded angle. • The ECM cyclically outputs the drive and stop signals for the OCV and when the difference between the VVT’s target advance angle and the actual advance angle has come to the normal range, the diagnostic code display is canceled. |
| Trim sensor | • The control is continued with fixed sensor output as 3.5 V |
| ETV ECM | • The throttle opening is fixed to default with the throttle motor relay turned off. ECM controls the engine speed at the maximum of 2 000 r/min by operating the remote control lever. (The engine rpm is controlled both by altering the ignition timing and skipping ignition for intermittent misfiring.) |
| ETV motor | • The throttle opening is fixed to default with the throttle motor relay turned off. ECM controls the engine speed at the maximum of 2 000 r/min by operating the remote control lever. |
| ETV | • The throttle opening is fixed to default with the throttle motor relay turned off. • ECM controls the engine speed at the maximum of 2 000 r/min by operating the remote control lever. |
| Sub BCM | • The main BCM controls the engine appropriately. |
| DBW system | • ECM causes the shift to return and fix to the neutral position and controls the engine speed to idling. |
| ESA ECM ESA motor ESA |
• ECM turns off the shift motor relay and fixes the shift position to that when the failure occurred. The engine rpm is controlled with ECM at the maximum of 2 000 r/min by operating the remote control lever. |
| Knock sensor | • The ignition timing delays with the predetermined amount. |
| O2 sensor | • The fuel injection amount is controlled with the base map. (The O2 feedback can not be executed.) |
| O2 sensor heater | • The fuel injection amount is controlled with the base map. (The O2 feedback can not be executed.) |
| Model distinction switch (Select terminal) |
• The original model (rotation) discrimination is retained. • The state that ECM is memorizing now is continued. |
There is no back-up system for the ECM itself. The engine will stop if it has failed.
