Exhaust Brake Control System Check - Isuzu N 2008 Series Workshop Manual

Exhaust Brake Control System Check

Description
The exhaust brake control system consists of the ECM,
the intake throttle valve, the exhaust brake valve, the
exhaust brake solenoid valve and the exhaust brake
switch. The ECM commands the intake throttle
solenoid valve and the exhaust brake solenoid valve to
close each valve based on vehicle running conditions
and exhaust brake switch input signal.
Exhaust Brake Control Operation
• The exhaust brake switch is ON.
• The engine is running.
• The accelerator pedal is not depressed.
• The gearshift clutch is not disengaged (Smoother).
• The clutch pedal is not depressed (manual
transmission).
Circuit/ System Testing Exhaust Brake Control System Check (1 of 2)
Step
Did you perform the Diagnostic System Check -
1 Engine Controls?
1. Verify whether the instrument panel (IP)
cluster is operational.
2. Turn ON the ignition, with the engine OFF.
2
3. Apply the exhaust brake switch ON and OFF.
Does the exhaust brake indicator lamp turn ON and
OFF with each switch transition?
1. Drive the vehicle in order to gain exhaust
brake ON time long enough.
2. Apply the exhaust brake switch ON.
3. Release the accelerator pedal.
3
Does exhaust brake apply enough (if the vehicle
speed is reduced by applying the exhaust brake but
engine valve noise is heard, intake throttle valve
may not be closed enough)?
1. Reenter the exhaust brake control.
2. Apply the accelerator pedal while in exhaust
brake control.
4
Does the exhaust brake control cancel?
Notice: If no Smoother is installed, skip to Step 6.
1. Reenter the exhaust brake control.
2. Operate the selector lever while in exhaust
5
brake control.
Does the exhaust brake control cancel?
1. Reenter the exhaust brake control.
2. Apply the clutch pedal while in exhaust brake
6
control.
Does the exhaust brake control cancel?
Action
Engine Control System (4JJ1)
• The vehicle speed is higher than predetermined
range.
Test Description
The number below refers to the step number on the
Circuit/ System Table.
4. 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.
8. If the Exhaust Brake Solenoid Command parameter
indicates OFF, use the scan tool to observe the Vehicle
Speed, Accelerator Pedal Position and Clutch Pedal
Switch parameters which allows the exhaust brake
control. Refer to engine control wirings and Scan Tool
Data List for diagnosis.
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 Step 4
—
Go to Step 5
—
System OK
—
System OK
1A-309
No
Go to Diagnostic
System Check -
Engine Controls
Go to 2 of 2 Step 1
Go to Step 7
Observe the
Accelerator Pedal
Position parameter
for accelerator pedal
position sensor
diagnosis
Go to Diagnostic
System Checks -
Transmission
Controls in Section
5A Transmission
Control System
Go to Step 9