Engine Start-Up Mode

ENGINE START-UP MODE
This is an Open Loop mode. The following actions occur when the starter motor is engaged.

The Jeep/Truck Engine Controller (JTEC) receives inputs from:
- Battery voltage
- Engine coolant temperature sensor
- Crankshaft position sensor
- Intake manifold air temperature sensor
- Manifold absolute pressure (MAP) sensor
- Throttle position sensor (TPS)
- Starter motor relay
- Camshaft position sensor signal

The JTEC monitors the crankshaft position sensor. If the JTEC does not receive a crankshaft position sensor signal within 3 seconds of cranking the engine, it will shut down the fuel injection system.

The fuel pump is activated by the JTEC through the fuel pump relay

Voltage is applied to the fuel injectors with the ASD relay by the JTEC. The JTEC will then control the injection sequence and injector pulse width by turning the ground circuit to each individual injector on and off.

The JTEC determines the proper ignition timing according to input received from the crankshaft position sensor.