Maintenance Manual for J2 Sedan
Electronic Control System
of Engine
167
related to the sensor and actuator can be read with the diagnosis apparatus, and the actuator may be
driven forcibly in some cases.
12. Other Control Functions
1) Fuel Injection Pump
With relay connected, the fuel injection pump will be energized when the crankshaft starts to rotate or
with engine running.
2) Fan Relay Control
The speeds of the radiator fan and condenser fan is controlled with the engine coolant temperature,
vehicle speed and air conditioner switch signal (AC).
III. On-board Diagnosis System
1. Description
On-board diagnosis system (hereinafter referred to as OBD system) is the diagnosis system integrated in
the engine control system to monitor the trouble components affecting the emission as well as the main
function state of the engine. It is capable of identifying, storing and showing the trouble information
through the self-diagnosis malfunction indicator lamp (MIL).
2. Trouble Information Record
Electronic control module constantly monitors the sensor, actuator, associated circuit, malfunction
indicator lamp (MIL) and battery voltage etc. as well as even the electronic control module itself, and
carries out the credibility detection for the output signal of sensor, the drive signal of actuator and the
internal signal (such as
λ
closed-loop control, coolant temperature, idling speed control and battery
voltage control etc.). Once a trouble is found in some link or a signal value is incredible, the electronic
control module immediately sets the trouble information record in RAM memory. Trouble information
record is stored in form of DTC and shown based on the order in which the troubles present.
The troubles can be divided into “steady-state trouble" and "sporadic trouble" according to their
occurrence frequencies (for example, because of short term open circuit of harness or poor contact of
connector).
