Isuzu KB P190. Manual - part 815

Engine Management – V6 – General Information 

Page 6C1-1–18 

 

3.12 Immobiliser 

System 

The vehicle incorporates an immobiliser system. After the ignition switch is turned to the ON position, and the powertrain 
interface module (PIM) has authenticated the immobiliser control unit (ICU), the PIM sends an encrypted security code to 
the engine control module (ECM). The ECM compares the received security code with its own security code, and if it is 
valid, the ECM enables the vehicle to be started. For further information and diagnosis of the immobiliser system, refer to 
11A Immobiliser. 

For further information on the PIM, refer to 6E1 Powertrain Interface Module – V6. 

Engine Management – V6 – General Information 

Page 6C1-1–19 

 

4 

Component Description and 
Operation 

4.1 

A/C Refrigerant Pressure Sensor 

The engine control module (ECM) applies a positive 5 V reference voltage and ground to the air-conditioner (A/C) 
refrigerant pressure sensor. The A/C refrigerant pressure sensor provides signal voltage to the ECM that is proportional 
to the A/C refrigerant pressure. The ECM monitors the A/C refrigerant pressure sensor signal voltage to determine the 
refrigerant pressure. 

• 

The A/C refrigerant pressure sensor voltage increases as the refrigerant pressure increases. 

• 

When the ECM detects the refrigerant pressure exceeds a predetermined value, the ECM activates the cooling 
fans to reduce the refrigerant pressure. 

• 

When the ECM detects the refrigerant pressure is too high or too low, the ECM disables the A/C clutch to protect 
the A/C compressor from damage. 

4.2 

Brake Pedal Switch Assembly 

Stop Lamp and Initial Brake Apply Switch 

The stop lamp and initial brake apply switch assembly (1) is 
located on the brake pedal support. 

The engine control module (ECM) uses the brake pedal 
switch inputs to determine when the brake pedal is 
depressed. 

The ECM uses the two break pedal switch inputs for:- 

• 

Enabling cruise control, 

• 

Brake torque management,  

• 

Cross referencing the stop lamp switch against the 
initial brake apply switch for correct operation. 

For further information on brake torque management,  
refer to 3.7 

Brake Torque 

Management. 

For further information on the cruise control system, refer to 
3.6 

Cruise Control System. 

Figure 6C1-1 – 13 

Stop Lamp Switch 

The stop lamp switch contacts are normally open with the brake pedal at rest and closed when the brake pedal is 
depressed. 

Initial Brake Apply Switch 

The initial brake apply switch contacts are normally closed with the brake pedal at rest and open when the brake pedal is 
depressed. 

 

Engine Management – V6 – General Information 

Page 6C1-1–20 

 

4.3 

Barometric Pressure Sensor 

The barometric pressure (BARO) sensor measures 
barometric (atmospheric) pressure. The ECM uses this 
signal to make corrections to the operating parameters of 
the system based on changes in air density, since the 
oxygen content of atmospheric air varies proportionally to air 
density (barometric / atmospheric pressure). Barometric 
pressure is affected mainly by altitude and climate. 

The BARO sensor provides a voltage signal to the ECM that 
is a function of barometric pressure. It does this through a 
series of deformation resistors, which change resistance 
when a mechanical force is applied. This force is applied to 
the resistors by a diaphragm on which the atmospheric 
pressure acts. 

The ECM supplies the BARO sensor with a 5 V reference 
and a ground circuit. 

Figure 6C1-1 – 14 

4.4 

Camshaft Position Sensor 

The HFV6 engine is fitted with an inlet camshaft position 
(CMP) sensor. 

The CMP sensor is used by the ECM to determine the 
position of the camshafts. In conjunction with the crankshaft 
position sensor, the CMP enables the ECM to determine 
engine rotational position. 

Figure 6C1-1 – 15 

The CMP sensor operates on the dual-Hall sensing 
principle. The sensor contains two hall elements (1) which 
operate in conjunction with a two-track trigger wheel (2) 
mounted on the camshaft.  

As the tracks (3) on the trigger wheel pass the elements, 
magnetic flux affects a voltage in the Hall elements. The 
integrated circuit inside the sensor conditions the signal 
generated by the Hall elements to provide a rectangular 
wave on / off signal to the ECM. 

The ECM supplies the CMP sensors with a 5 V reference 
and ground circuit.  

Figure 6C1-1 – 16 

Engine Management – V6 – General Information 

Page 6C1-1–21 

 

4.5 

Crankshaft Position Sensor 

In conjunction with the camshaft position sensor, the 
crankshaft position (CKP) sensor enables the ECM to 
determine engine rotational position. The CKP is also used 
to determine engine speed (rpm). 

Figure 6C1-1 – 17 

The CKP sensor (1) operates on the variable reluctance 
(pulse generator) sensing principle. It contains a magnet 
and pickup coil and is used in conjunction with a 58 tooth 
ferromagnetic reluctor wheel (2) attached to the 
crankshaft (3). 

As the crankshaft rotates, the reluctor wheel revolves past 
the CKP, causing fluctuations in the magnetic field inside 
the sensor. This action creates an AC voltage across the 
pickup coil which is processed by the ECM. An increase in 
engine speed will increase the output voltage and 
frequency. 

The reluctor wheel teeth are placed six degrees apart. 
Having only 58 teeth leaves a 12 degree open span, which 
creates a signature pattern that enables the ECM to 
determine the crankshaft position. The ECM determines 
which two cylinders are approaching the top dead centre 
based on the crankshaft position sensor signal. The CMP 
sensor signals are used by the ECM to determine which 
cylinder is on the firing stroke. 

Figure 6C1-1 – 18