Isuzu 2008MY N Series Workshop Manual page 180

Step
Connect a DMM between the 5 volts reference
circuit and low reference circuit (pin 1 and 5 of E-
15).
5
Is the DMM voltage more than the specified
value?
Observe the EGR Position 1, 2 and 3 parameter
with a scan tool while momentarily jumping a 3-
amp fused jumper wire across the EGR valve
harness connector between each signal circuit and
the 5 volts reference circuit.
• EGR position 1: pins 1 and 4 of E-15
6
• EGR position 2: pins 1 and 3 of E-15
• EGR position 3: pins 1 and 2 of E-15
Is there parameter which did not indicate High
when the circuit is jumpered?
Important: The EGR position sensor may be
damaged if the sensor signal circuit is shorted to a
voltage source.
1. Test the signal circuits (which ever parameter
indicates High at Step 3) between the ECM
(pins 93, 94 and 99 of E-12) and the EGR
valve (pins 2, 3 and 4 of E-15) for the following
7
conditions:
• 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 EGR position 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
8
ECM (pin 87 of E-12) and the EGR valve (pin
1 of E-15) for an open circuit or high
resistance.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
Notice: The EGR 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
9
ECM (pin 101 of E-12) and the EGR valve (pin
5 of E-15) 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
4.5 volts
Go to Step 6
—
Go to Step 10
—
Go to Step 16
—
Go to Step 16
—
Go to Step 16
1A-177
No
Go to Step 9
Go to Step 11
Go to Step 15
Go to Step 13
Go to Step 13