Diagnostic Trouble Code (Dtc) P0122 Tp Sensor Circuit Low Voltage - Isuzu 1999 RODEO Workshop Manual

6E2–152
RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) P0122 TP Sensor Circuit Low Voltage

Circuit Description
The throttle position (TP) sensor circuit provides a voltage
signal that changes relative to throttle blade angle. The
signal voltage will vary from below 0.6 volts at closed
throttle to about 4.5 volts at wide open throttle (WOT).
The TP signal is used by the powertrain control module
(PCM) for fuel control and many of the PCM-controlled
outputs.
Conditions for Setting the DTC
f The ignition is "ON."
f TP sensor signal voltage is less than 0.22 volt for a total
of 0.78 second over a 1.5-second period.
Action Taken When the DTC Sets
f The PCM will illuminate the malfunction indicator lamp
(MIL) the first time the fault is detected.
f The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
f The PCM will use a default throttle position based on
mass air flow and RPM.
Conditions for Clearing the MIL/DTC
f The PCM will turn the MIL "OFF" on the third
consecutive trip cycle during which the diagnostic has
been run and the fault condition is no longer present.
f A history DTC P0122 will clear after 40 consecutive
warm-up cycles have occurred without a fault.
f DTC P0122 can be cleared by using the Tech 2 "Clear
Info" function or by disconnecting the PCM battery
feed.
Diagnostic Aids
Check for the following conditions:
f Poor connection at PCM – Inspect harness connectors
for backed-out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal-to-wire connection.
f The TP Sensor shares a 5 Volt reference with the EGR
Valve.
If these codes are also set, it could indicate a
problem with the 5 Volt reference circuit or
components itself.
f The TP Sensor share a ground with the EGR Valve and
the IAT Sensor.
f Damaged harness – Inspect the wiring harness for
damage. If the harness appears to be OK, observe the
throttle position display on the Tech 2 while moving
connectors and wiring harnesses related to the TP
sensor. A change in the display will indicate the
location of the fault.
If DTC P0122 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage since the DTC was last set.
If it is determined that the DTC occurs intermittently,
performing the DTC P1122 Diagnostic Chart may isolate
the cause of the fault.
D06RW059