Isuzu 2008MY N Series Workshop Manual page 221

1A-218 Engine Control System (4HK1)
Step
1. Remove the intake duct that is connected to
the intake throttle valve.
2. Inspect the intake throttle valve for the
following conditions:
• Restricted intake throttle valve by foreign
materials
• Excessive deposits at throttle bore
4
• Bent butterfly valve
Notice: Replace the intake throttle valve if
there is any sticking.
3. Repair or replace as necessary.
Did you find and correct the condition?
1. Turn OFF the ignition.
2. Disconnect the intake throttle valve harness
connector.
3. Inspect
connections and corrosion at the harness
connector of the intake throttle valve (pins 1,
2, 4, 5 and 6 of E-16).
4. Disconnect the ECM harness connector.
5. Inspect
5
connections and corrosion on each intake
throttle valve circuit at the harness connector
of the ECM (pins 85, 95, 104, 109 and 112 of
E-12).
6. Test for an open circuit or high resistance on
each circuit.
7. Repair the connection(s) or circuit(s) as
necessary.
Did you find and correct the condition?
1. Test the solenoid circuits between the ECM
(pins 104 and 112 of E-12) and the intake
throttle valve (pins 1 and 2 of E-16) for the
following conditions:
• A short to ground
• A short to battery or ignition voltage
6
• A short circuit each other
• A short to the intake throttle position
sensor circuit(s)
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
Replace the intake throttle valve. Refer to Intake
Throttle Valve in Section 1B Engine Mechanical.
7
Did you complete the replacement?
Action
for an intermittent,
for an intermittent,
Value(s)
—
for poor
for poor
—
—
—
Yes
Go to Step 8 Go to Step 5
Go to Step 8 Go to Step 6
Go to Step 8 Go to Step 7
Go to Step 8
No
—