Isuzu N 2008 Series Workshop Manual page 123

1A-120 Engine Control System (4JJ1)
Circuit/ System Testing DTC P0193
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. Monitor the DTC Information with a scan tool.
Is DTC P0651 also set?
Observe the Fuel Rail Pressure (FRP) Sensor
parameter with a scan tool.
3
Is the FRP Sensor parameter more than the
specified value?
1. Turn OFF the ignition.
2. Disconnect
connector.
3. Connect a DMM between the signal circuit
4
(pin 2 of E19) and a known good ground.
4. Turn ON the ignition, with the engine OFF.
Is the DMM voltage more than the specified value?
1. Connect a test lamp between the signal circuit
(pin 2 of E19) and a known good ground.
2. Connect a DMM between the probe of the test
5
lamp and a known good ground.
Is the DMM voltage more than the specified value?
Connect a 3-amp fused jumper wire between the
signal circuit and the low reference circuit of the
sensor harness (pins 1 and 2 of E19).
6
Is the FRP Sensor parameter less than the
specified value?
Notice: The FRP 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
7
ECM (pin 101 of E12) and the FRP sensor
(pin 1 of E19) for an open circuit or high
resistance.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
1. Test the signal circuit between the ECM (pins
82 and 90 of E12) and the FRP sensor (pin 2
of E19) for an open circuit or high resistance.
8
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
1. Test the signal circuits between the ECM (pins
82 and 90 of E12) and the FRP sensor (pin 2
of E19) for a short to any 5 volts reference
9 circuit.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?
Action
the FRP sensor harness
Value(s) Yes
—
Go to Step 2
—
Go to DTC P0651
4.5 volts
Go to Step 4
5.5 volts
Go to Step 10
4.5 volts
Go to Step 9
0.1 volts
Go to Step 11
—
Go to Step 15
—
Go to Step 15
—
Go to Step 15
No
Go to Diagnostic
System Check -
Engine Controls
Go to Step 3
Go to Diagnostic
Aids
Go to Step 5
Go to Step 6
Go to Step 7
Go to Step 8
Go to Step 12
Go to Step 14