Cold Start Injector Time Switch

During cranking, the starter relay is energized (contacts in relay close). This allows voltage to cold start injector. The time switch contains a heat-sensitive bimetal switch. Three heat sources affect the bimetal switch: engine coolant and 2 separate heater coils inside of the time switch. Bimetal switch remains closed until temperature exceeds 72°F (22°C).

• If bimetal switch contacts are closed, current flows to ground through the time switch contacts, resulting in cold start injection. Under this condition, voltage is NOT present at ECM terminal STJ (terminal No. 78 of ECM connector "B").
• If the bimetal switch contacts are open, current does NOT flow to ground through the time switch. Under this condition, voltage is present at ECM terminal STJ. If ECM senses engine coolant temperature is less than 140°F (60°C), the ECM grounds the cold start injector circuit. If engine coolant temperature is 140°F (60°C) or more, cold start injection will not occur.