Prizm L4-1600cc 1.6L DOHC VIN 5 (1989)
Cold Start Injector Circuit
CIRCUIT DESCRIPTION:
The cold start injector valve is used to provide additional fuel during the crank mode to improve cold start-ups. This circuit is important when engine
coolant temperature is low because the other injectors are not pulsed "ON" long enough to provide the needed amount of fuel to start. The circuit is
activated only in the crank mode. The power is supplied directly from the starter solenoid and is protected by a fuse. The system is controlled by a cold
start fuel injection switch which provides a ground path for the valve during cranking when engine coolant is below 35°C (95°F). The switch contains a
bimetal material which opens at a specified coolant temperature. This bimetal is also heated by the winding in the thermal switch which allows the valve
to stay "ON" for 8 seconds at -20°C (-5°F) coolant. The time the switch will stay closed varies inversely with coolant temperature. In other words, as the
coolant temperature goes up, the cold start injector valve "ON" time goes down.
TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.
1.
Disconnecting the distributor 2-way connector will disable the other injectors. The amount of pressure drop depends on the temperature of the
engine.
2.
This test will determine the continuity through the switch to ground.
