Isuzu 1999 RODEO Workshop Manual page 766

f Faulty Throttle Position sensor – With the ignition key
ON engine OFF observe the TP sensor display on the
Tech 2 while slowly depressing the accelerator to wide
open throttle. If a voltage over 4.88 volts is seen at any
point in normal accelerator travel, replace the TP
sensor.
If Diagnostic Trouble Code P0123 cannot be duplicated,
the information included in the Failure Records data can
be useful in determining vehicle mileage since the
Diagnostic Trouble Code was last set. If it is determined
that the Diagnostic Trouble Code occurs intermittently,
performing theDiagnostic
Diagnostic Chart may isolate the cause of the fault.
Step
1 Was the "On–Board Diagnostic (OBD) System Check"
performed?
2 1. Ignition ON, engine OFF.
2. With the throttle closed, observe the "Throttle
Position Sensor" display on the Tech 2.
Is the "Throttle Position Sensor" above the specified
value?
3 1. Ignition ON, engine OFF.
2. Review and record Tech 2 Failure Records data.
3. Operate the vehicle within Failure Records
conditions as noted.
4. Using a Tech 2, monitor "Diagnostic Trouble Code"
info for Diagnostic Trouble Code P0123.
Does the Tech 2 indicate Diagnostic Trouble Code
P0123 failed.
4 1. Disconnect the Throttle Position sensor electrical
connector.
2. Observe the "Throttle Position Sensor" display on
the Tech 2.
Is the "Throttle Position Sensor" near the specified
value? (if no, start with the diagnosis chart for other
sensors in the circuit and see if 5V returns.)
5 Probe the sensor ground circuit at the Throttle Position
sensor harness connector with a test light connected to
B+.
Is the test light ON?
6 1. Ignition OFF disconnect the PCM.
2. Ignition ON engine OFF.
3. Check for a short to voltage on the TP sensor signal
circuit.
4. If the TP sensor signal circuit is shorted, repair it as
necessary.
Was the TP sensor signal circuit shorted?
RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
Trouble Code P1121
DTC P0123 – TP Sensor Circuit High Input
Action
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart:
7. Components that share the TP sensor 5 volt
reference circuit include the following devices:
f EGR valve
f Fuel Tank Pressure sensor
f MAP sensor
Disconnect the component while observing the
Throttle Position sensor display on the Tech 2. If
the reading changes drastically when this
component is disconnected, replace the
component that affected the reading.
Value(s)
— Go to Step 2
4.78 V Go to Step 4
— Go to Step 4
0 V Go to Step 5
— Go to Step 7
— Verify repair
6E1–139
Yes No
Go to OBD
System
Check
Go to Step 3
Refer to
Diagnostic
Aids
Go to Step 6
Go to Step
10
Go to Step
12