Engine Warm Up Control System Check - Isuzu N 2008 Series Workshop Manual

1A-306 Engine Control System (4JJ1)

Engine Warm Up Control System Check

Description
The engine warm up system consists of the ECM, the
intake throttle valve, the exhaust brake valve, the
exhaust brake solenoid valve and the engine warm up
switch. The engine warm up system is operated when
the engine coolant temperature is low, which promotes
engine warm up. The ECM commands the intake
throttle solenoid valve and the exhaust brake solenoid
valve to close each valve based on engine coolant
temperature and warm up request switch input signal.
Engine Warm Up Control Operation
• The engine warm up switch is ON.
• The engine is running.
• The accelerator pedal is not depressed.
Circuit/ System Testing Engine Warm Up Control System Check
Step
Did you perform the Diagnostic System Check -
1 Engine Controls?
Does the exhaust brake operate correctly?
2
1. Install a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Turn ON the ignition, with the engine OFF.
3
4. Monitor the DTC Information with a scan tool.
Is DTC P0117, P0118, P0122, P0123, P0477,
P0478, P0638, P0641, P0651 or P0697 set?
1. Park the vehicle.
2. Make sure the idle up control knob to the
lowest
direction)
3. Cool down the engine as necessary (allow
engine coolant temperature to cool down at
4
least 70°C [158°F]).
4. Start the engine.
5. Turn ON the engine warm up switch.
Are the intake throttle valve and the exhaust brake
valve closed when switched ON?
Turn OFF the engine warm up switch.
5
Does the engine warm up control cancel?
1. Turn ON the engine warm up switch.
2. Press the accelerator pedal.
6
Does the engine warm up control cancel?
Action
position. (Full counterclockwise
• The engine coolant temperature is less than 77°C
(170°F)
• The vehicle is not running.
Test Description
The number below refers to the step number on the
Circuit/ System Table.
6. Use the scan tool to observe the Accelerator Pedal
Position. The Accelerator Pedal Position parameter
should change linearly from 0 to 100% according to the
accelerator pedal operation.
7. Use the scan tool to observe the Vehicle Speed. The
Vehicle Speed parameter should indicate correct
vehicle speed.
Connector End View Reference: Engine Controls
Connector End Views or ECM Connector End Views
Value(s) Yes
—
Go to Step 2
—
Go to Step 3
—
Go to Applicable
DTC
—
Go to Step 5
—
Go to Step 6
—
Go to Step 7
No
Go to Diagnostic
System Check -
Engine Controls
Go to Exhaust
Brake Control
System Check
Go to Step 4
Go to Step 8
Go to Step 16
Observe the
Accelerator Pedal
Position parameter
for accelerator pedal
position sensor
diagnosis