Fail Safe Operation

ECU Back-up Functions

1. Fail-Safe Function
When an abnormality occurs in signal from a sensor, the ECU ignores that signals and assumes a pre-programmed value that allows the engine to continue to run.
2. Back-up Function
When an abnormality occurs in the ECU itself, the injections are controlled by a back-up circuit independent of the system in order to permit minimal driving.
3. Self-diagnosis Function (Check Engine warning light and LED indicator).
When an abnormality occurs in a signal from a sensor, the ECU lights the Check Engine warning light, stores the failure code in erasable memory and indicates the code with a LED on the ECU anytime the ignition is on. When the ignition is initially turned on, the ECU supplies ground for the Check Engine warning light for about 2 seconds.