Jetta L4-1781cc 1.8L SOHC (1987)
optimum ignition timing point from an internal timing "map." The knock sensor allows the Digifant E.C.U. to maintain ignition timing as advanced as
possible for good performance while eliminating the possibility of detonation or spark knock.
Control current for the idle stabilizer. This regulates the opening and closing of the idle stabilizer valve to control the amount of idle air that bypasses
the throttle plate. If the idle speed varies from the value stored in the E.C.U., it compensates by opening or closing the stabilizer valve.
The E.C.U. also receives a signal when the A/C compressor clutch is activated. The E.C.U. increases control current by a predetermined amount when
the A/C clutch is activated. This prevents a severe idle speed dip before the idle stabilization system can compensate. The current increase remains
effective for as long as the compressor clutch is engaged.
The control current output also increases idle speed during warm-up enrichment and for a short period following a hot start at high outside temperatures.
Relay Location
Power Supply Relay
Provides battery voltage to the E.C.U. in the Colt. Provides battery voltage to the E.C.U. AND the fuel injectors In the Jetta.
Fuel Pump Relay
Provides battery voltage to the fuel pumps and fuel injectors In the Golf. Provides battery voltage to the fuel pumps and oxygen sensor heating
element In the Jetta.
Note: These relay locations are valid for vehicles produced before January 1989.
Engine Management System (Digifant II)
Digifant II Engine Management System
