Isuzu 2008MY N Series Workshop Manual page 211

1A-208 Engine Control System (4HK1)
Step
1. Connect a DMM between the ignition voltage
feed circuit (pin 1 of J-30) and a known good
ground.
6
2. Turn ON the ignition, with the engine OFF.
Is the DMM voltage more than the specified
value?
Connect a DMM between the voltage supply circuit
(pin 2 of J-30) and a known good ground.
7
Is the DMM voltage more than the specified
value?
Repair the open circuit or high resistance on the
ignition voltage feed circuit between the ECM MAIN
(15A) fuse and the dropping resistor (pin 1 of J-30).
8
Check the ECM MAIN (15A) fuse first.
Did you complete the repair?
1. Test the voltage supply circuit between the
ECM (pin 35 of J-14) and the dropping resistor
(pin 2 of J-30) for an open circuit or high
9 resistance.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
1. Test the voltage supply circuit between the
ECM (pin 35 of J-14) and the dropping resistor
(pin 2 of J-30) for the following conditions:
• A short to ground
10
• A short to battery or ignition voltage
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
1. Test the 12 volts reference circuit between the
ECM (pin 23 of J-14) and the MAF sensor (pin
1 of J-38) for the following conditions:
• A short to ground
11
• A short to battery or ignition voltage
• A short to the low reference
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
1. Inspect for an intermittent and for poor
connections at the harness connector of the
dropping resistor (pins 1 and 2 of J-30).
12
2. Repair the connection(s) as necessary.
Did you find and correct the condition?
1. Inspect for corrosion at the harness connector
of the MAF sensor (pin 1 of J-38).
13
2. Repair the connection(s) as necessary.
Did you find and correct the condition?
Action Value(s) Yes
18.0 volts
Go to Step 7
13.0 volts
Go to Step 12
—
Go to Step 18
—
Go to Step 18
—
Go to Step 18
—
Go to Step 18
—
Go to Step 18
—
Go to Step 18
No
Go to Step 8
Go to Step 9
—
Go to Step 14
Go to Step 11
Go to Step 17
Go to Diagnostic
Aids
Go to Step 16