Isuzu N 2008 Series Workshop Manual page 115

1A-112 Engine Control System (4JJ1)
Circuit/ System Testing DTC P0123
Step
Did you perform the Diagnostic System Check -
1 Engine Controls?
1. Install a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
2
4. Observe the Intake Throttle Position Sensor
parameter with a scan tool.
Is the Intake Throttle Position Sensor parameter
more than the specified value?
Monitor the DTC Information with a scan tool.
3
Is DTC P0697 also set?
1. Turn OFF the ignition.
2. Disconnect the intake throttle valve harness
connector.
4
3. Turn ON the ignition, with the engine OFF.
Is the Intake Throttle Position Sensor parameter
less than the specified value?
1. Turn OFF the ignition.
2. Disconnect the intake throttle valve harness
connector.
5
3. Turn ON the ignition, with the engine OFF.
Is the Intake Throttle Position Sensor parameter
less than the specified value?
Connect a test lamp between the low reference
circuit (pin 3 of E16) and battery voltage.
6
Does the test lamp illuminate?
Important: The intake throttle position sensor may
be damaged if the sensor signal circuit is shorted to
a voltage source.
1. Test the signal circuit between the ECM (pin
85 of E12) and the intake throttle valve (pin 5
of E16) for the following conditions:
7
• A short to battery or ignition voltage
• A short to any 5 volts reference
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
Notice: The intake throttle position sensor shares
the low reference circuit with other sensors. A fault
condition in the low reference circuit may set DTCs
on sensors that share this circuit.
1. Test the low reference circuit between the
8
ECM (pin 109 of E12) and the intake throttle
valve (pin 3 of E16) for an open circuit or high
resistance.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
Action Value(s) Yes
—
Go to Step 2
4.9 volts
Go to Step 3
—
Go to Step 4
0.1 volts
Go to DTC P0697
0.1 volts
Go to Step 6
—
Go to Step 9
—
Go to Step 13
—
Go to Step 13
No
Go to Diagnostic
System Check -
Engine Controls
Go to Diagnostic
Aids
Go to Step 5
Go to Step 7
Go to Step 7
Go to Step 8
Go to Step 12
Go to Step 10