Integra L4-1590cc 1.6L DOHC FI (1987)
Electronic Control Unit: Description and Operation
The ECU contains memories for the basic discharge durations at various engine speeds and manifold pressures. The basic discharge duration, after
being read out from the memory, is further modified by signals sent from various sensors to obtain final discharge duration. The ECU is located under
the passenger seat and contains fail safe, back-up and self diagnostic functions.
In the fail safe function, the ECU ignores abnormalities is sensor signals and assumes a pre-programmed value that permits the engine to continue to
run until repairs can be completed.
In the back-up function, the ECU ignores abnormalities within itself, enabling injection to be controlled by a back-up circuit which is run independent
of the system.
The self diagnostic system consists of a PGM-FI warning light on the dash and red and yellow (Legend only) LED indicators on the ECU itself. When
an abnormality occurs in a signal from the various sensors, the ECU illuminates the warning light, stores the failure code in memory and indicates the
failure code with the red LED anytime the ignition switch is On. In addition, a self-test feature is available which initially illuminates the warning light
for two seconds whenever the ignition is first turned On. On Legend models, when the ECU detects that the electronic idle control valve (EICV) has
exceeded pre-programmed limits, the yellow LED will remain On or will blink, depending on the limit exceeded.
