Isuzu N 2008 Series Workshop Manual page 206

Step
1. Leave the DMM connected to the idle up
sensor harness connector.
2. Turn OFF the ignition.
3. Disconnect the accelerator pedal position
5
(APP) sensor harness connector.
4. Turn ON the ignition, with the engine OFF.
Does the DMM voltage change to more than the
specified value?
Notice: If no PTO throttle sensor is installed, skip
to Step 7.
1. Leave the DMM connected to the idle up
sensor harness connector.
2. Turn OFF the ignition.
6
3. Disconnect the PTO throttle sensor harness
connector.
4. Turn ON the ignition, with the engine OFF.
Does the DMM voltage change to more than the
specified value?
1. Test the 5 volts reference circuit between the
ECM (pin 42 of J14) and the following
components for a short to ground or short to
the low reference circuit:
• APP sensor 1 (pin 4 of B5)
7
• PTO throttle sensor (pin 3 of J39)
• Idle up sensor (pin 3 of B87)
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
1. Test the 5 volts reference circuit between the
ECM (pin 42 of J14) and the following
components for a short to battery or ignition
voltage.
• APP sensor 1 (pin 4 of B5)
8
• PTO throttle sensor (pin 3 of J39)
• Idle up sensor (pin 3 of B87)
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
Replace the idle up sensor. Refer to Idle Up Sensor
in Section 1I Engine Speed Control System.
9
Did you complete the replacement?
Replace the APP sensor. Refer to Accelerator
Pedal Sensor in Section 1I Engine Speed Control
10
System.
Did you complete the replacement?
Replace the PTO throttle sensor.
11
Did you complete the replacement?
Important: Replacement
programmed and learned.
12
Replace the ECM. Refer to ECM Replacement.
Did you complete the replacement?
Action
ECM must
Engine Control System (4JJ1)
Value(s)
4.5 volts
4.5 volts
—
—
—
—
—
be
—
Yes
Go to Step 10 Go to Step 6
Go to Step 11 Go to Step 7
Go to Step 13 Go to Step 12
Go to Step 13 Go to Step 12
Go to Step 13
Go to Step 13
Go to Step 13
Go to Step 13
1A-203
No
—
—
—
—