Isuzu 2008MY N Series Workshop Manual page 308

Step
Turn the idle up sensor to lowest position (full
counterclockwise direction).
5
Is the Idle Up Sensor parameter less than the
specified value?
1. Turn OFF the ignition.
2. Disconnect the idle up sensor harness
connector.
3. Connect a DMM between the 5 volts reference
circuit (pin 3 of B-87) and a known good
6
ground.
4. Turn ON the ignition, with the engine OFF.
Is the DMM voltage more than the specified
value?
Connect a 3-amp fused jumper wire between the 5
volts reference circuit and the signal circuit (pins 2
and 3 of B-87).
7
Is the Idle Up Sensor parameter more than
the specified value?
1. Turn OFF the ignition.
2. Disconnect the idle up sensor harness
connector.
8
3. Turn ON the ignition, with the engine OFF.
Is the Idle Up Sensor parameter less than the
specified value?
1. Turn OFF the ignition.
2. Disconnect the idle up sensor harness
connector.
9
3. Turn ON the ignition, with the engine OFF.
Is the Idle Up Sensor parameter less than the
specified value?
Connect a test lamp between the low reference
circuit (pin 1 of B-87) and battery voltage.
10
Does the test lamp illuminate?
Notice: The idle up sensor shares the 5 volts
reference circuit with other sensors. A fault
condition in the 5 volts reference circuit may set
DTCs on sensors that share this circuit.
1. Test the 5 volts reference circuit between the
11
ECM (pin 42 of J-14) and the idle up sensor
(pin 3 of B-87) for an open circuit or high
resistance.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
Action
Engine Control System (4HK1)
Value(s) Yes
0.1 volts
Go to Step 6
4.5 volts
Go to Step 7
4.5 volts
Go to Step 15
0.1 volts
Go to DTC P0641
0.1 volts
Go to Step 10
—
Go to Step 15
—
Go to Step 19
1A-305
No
Go to Step 9
Go to Step 11
Go to Step 12
Go to Step 13
Go to Step 13
Go to Step 14
Go to Step 16