CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
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Cooling fan relay
2.3. INTRODUCTION OF SYSTEM MALFUNCTION DIAGNOSIS FUNCTION
2.3.1. MALFUNCTION INFORMATION RECORD
The ECU monitors sensor, actuator, related circuit, malfunction indicator and accumulator
voltage etc., and EUC itself continuously. At the same time the ECU inspect the reliability
test on sensor signal output, actuator driving signal and internal signal (e.g.: closed loop
control, coolant temperature, knock control, idle engine speed and accumulator voltage etc.).
ECU will set the malfunction record on RAM malfunction memory immediately once the
malfunction or the unlikelihood signal is detected. The malfunction information is recorded
by malfunction code and displayed according to its appeared order, dividing malfunction into
“steady malfunction”and “contingency malfunction”(for example the malfunction is caused
by short time cable braking or bad contact of the inserts) according to its appeared frequency.
Chart 2.4 EFI System Malfunction Diagnosis Principle Chart
2.3.2, CONTROL STRATEGY OF FAILURE LAMP
When there is no trouble:
★ The failure lamp is lighting and die out within 4 seconds after the ignition switch is ON
★ Starting within 4 seconds, the failure lamp dies when the engine speed signal is found;
★ The failure lamp winking at 2HZ frequency when the K cable contact to ground more
than 2.5 seconds.
When there is a trouble:
★ The failure lamp always on light when the ignition switch is ON;
★ Start and die out when the engine speed signal is detected; if the failure lamp was defined
as lighting mode, it will always on light after reach its confirmed conditions;
Function Diagnosis Function Diagnosis
ECU
Actuator
Sensor
Control Order
Data Collection
Engine
