Isuzu 2008MY N Series Workshop Manual page 382

ECM Input & Output
Sensor inputs
Intake air temperature (IAT) sensor
Mass air flow (MAF) sensor
Engine coolant temperature (ECT) sensor
Fuel temperature (FT) sensor
Barometric pressure (BARO) sensor
Boost pressure sensor
Accelerator pedal position (APP) sensor
EGR position sensor
Intake throttle position sensor
Crankshaft position (CKP) sensor
Camshaft position (CMP) sensor
Fuel rail pressure (FRP) sensor
Vehicle speed sensor (VSS)
Exhaust differetial pressure sensor
Exhaust temperature sensor 1
Exhaust temperature sensor 2
Idle up sensor
PTO throttle sensor
Switch input
Ignition switch (ON/start position)
Clutch switch (M/T)
Parking brake switch
Neutral switch
DPD switch
Engine warmup switch
Exhaust brake switch
A/C switch
Diagnostic request switch
Engine oil level switch
Cruise main switch
Cruise control switch
ECM Voltage Description
The ECM supplies a buffered voltage to various
switches and sensors. The ECM can do this because
resistance in the ECM is so high in value that a test
lamp may not illuminate when connected to the circuit.
An ordinary shop voltmeter may not give an accurate
reading because the voltmeter input impedance is too
low. Use a 10-megaohm input impedance DMM, to
ensure accurate voltage readings. The input and/ or
output devices in the ECM include analog-to-digital
converters, signal buffers, counters, and special
drivers. The ECM controls most components with
electronic switches which complete a ground circuit
when turned ON.
Engine Control System (4HK1)
Fuel injection control
Fuel rail pressure (FRP) regulator
Fuel injector #1
Fuel injector #2
Fuel injector #3
Fuel injector #4
Actuator control
Intake throttle solenoid
EGR solenoid
Exhaust brake solenoid
Exhaust throttle solenoid
Relay control outputs
Glow relay
Starter cut relay
ECM
ECM main relay
Lamp control
Malfunction indicator lamp (MIL)
Service vehicle soon (SVS) lamp
Glow indicator lamp
Exhaust brake lamp
Cruise main lamp
Cruise set lamp
DPD lamp or DPD indicators on MID
Check engine oil level warning on MID
Communication
Controller area network (CAN)
Keyword serial data
(Except Euro4 Specification)
Aftermarket Electrical and Vacuum Equipment
Aftermarket or
equipment is defined as any equipment which connects
to the vehicle's electrical or vacuum systems that is
installed on a vehicle after the vehicle leaves the
factory. No allowances have been made in the vehicle
design for this type of equipment. No add-on vacuum
equipment should be added to this vehicle. Add-on
electrical equipment must only be connected to the
vehicle's electrical system at the battery power and
ground. Add-on electrical equipment, even when
installed to these guidelines, may still cause the
powertrain system to malfunction. This may also
include equipment not connected to the vehicle
electrical system such as portable telephones and
audios. Therefore, the first step in diagnosing any
powertrain fault is to eliminate all aftermarket electrical
equipment from the vehicle. After this is done, if the
fault still exists, the fault may be diagnosed in the
normal manner.
add-on electrical and
1A-379
LNW81AMF000401
vacuum