Engine Warm-Up Mode

ENGINE WARM-UP MODE
This is an Open Loop mode. During engine warm-up, the Jeep/Truck Engine Controller (JTEC) receives inputs from:
- Battery voltage
- Crankshaft position sensor
- Engine coolant temperature sensor
- Intake manifold air temperature sensor
- Manifold absolute pressure (MAP) sensor
- Throttle position sensor (TPS)
- Camshaft position sensor signal (in the distributor)
- Park/neutral switch (gear indicator signal auto. trans. only)
- Air conditioning select signal (if equipped)
- Air conditioning request signal (if equipped) Based on these inputs the following occurs:
- Voltage is applied to the fuel injectors through the ASD relay by Jeep/Truck Engine Controller (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 adjusts engine idle speed through the idle air control (IAC) motor and adjusts ignition timing.
- The JTEC operates the A/C compressor clutch through the clutch relay. This is done if A/C has been selected by the vehicle operator and requested by the A/C thermostat.
- If the vehicle has a manual transmission, the up-shift lamp is operated by the JTEC.
- When engine has reached operating temperature, the JTEC will begin monitoring 02S sensor input. The system will then leave the warm-up mode and go into closed loop operation.