Description The crankshaft sensor is located in the front cover. The sensor is positioned over the crankshaft sprocket and consists of a Hall-effect device and a magnet (figure 5-38). The crankshaft sprocket has four teeth at 90° intervals. As the sprocket rotates, its teeth pass the sensor. • When no teeth of the sprocket are… Read More »
OPTICAL SENSOR Description The optical sensor is located in the fuel injection pump (figure 5-36) and includes the fuel temperature sensor. The optical sensor counts the pulses emitted by a disc in the injection pump. The disc is a silver-colored, film-like ring notched with two sets of notches. • The outer diameters consists of 512… Read More »
PCM timing control uses input data from the Accelerator Pedal Position (APP) sensors, intake air temperature sensor, optical sensor, and crankshaft position sensor (engine speed) to energize the injection timing stepper motor (figure 5-35).
Description The “Service Throttle Soon” (STS) in the instrument panel alerts the driver to conditions in the accelerator pedal position (APP) circuit that require attention. Under normal operation, the STS lamp illuminates when the ignition is “ON” and the engine is “OFF.” The lamp comes “ON” for approximately 2 seconds at key “ON” and turns… Read More »
Description The A/C signal comes from the A/C-heater control head in the vehicle and informs the PCM that the driver has turned the air conditioner “ON.” The PCM uses this information to adjust idle speed to compensate for A/C compressor load. A/C Signal Circuit Operation The A/C request signal is sent to the PCM on… Read More »
Description The fuel temperature sensor is part of the optical sensor (see figure 5-36). It is a thermistor that controls signal voltage to the PCM. Voltage from the sensor will vary inversely to fuel temperature (i.e. high temperature equals low voltage; low temperature equals high voltage). Resistance values for the sensor at various temperatures are… Read More »
Description The Engine Shutoff (ESO) solenoid is located on the injection pump (figure 5-30). When the ignition switch is “OFF,” the ESO solenoid is in the “No Fuel” position. It prevents fuel from entering the injection pump. At ignition startup, the PCM provides a ground for the solenoid. This pulls the ESO pintle upward, allowing… Read More »
The PCM has the ability to increase and decrease the amount of fuel to each cylinder to provide smooth idle operation. If the fuel correction amount exceeds defined limits, a code is set. The following codes identify cylinder balance faults: • DTC 91 — “Cylinder Balance Fault—#7 Cylinder” • DTC 92 — “Cylinder Balance Fault—#2… Read More »
Fuel Solenoid Driver Circuit Operation The fuel solenoid driver receives an inject-command signal from the PCM on CKT 984 (figure 5-29). The driver provides current-regulated output to the fuel solenoid that controls fuel pump metering injection. The driver also returns an injection pulse-width modulated (PWM) signal back to the PCM on CKT 985. This signal… Read More »
Description The 6.5L EFI PCM uses Accelerator Pedal Position (APP) sensors to control fuel delivery as requested by driver demands at the accelerator pedal. Three APP sensors are located in a module at the base of the accelerator pedal (figure 5-27). The APP module replaces the throttle linkage found on non-EFI 6.5L diesel engines. While… Read More »