Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Cold Starting System
During cold starting, additional fuel is injected into the intake manifolds by 2 cold start injectors. These injectors are controlled by the cold start relay and the thermotime switch.
The thermotime switch senses engine coolant temperature, and depending on temperature makes or breaks the ground circuit of the relay. When the starter circuit is activated, the cold start relay is energized with the ground circuit being completed by the thermotime switch.
The thermotime switch also limits the time that the relay is energized (12 seconds max.). The enrichment provided by the cold start system is in addition to the enrichment resulting from the coolant temperature sensors' signal to the electronic control unit.
If the temperature at the thermotime switch is above 95°F (35°C), the thermotime switch will not close and no cold start enrichment will take place.
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.