Isuzu 1999 RODEO Workshop Manual page 1617

6E2–374
RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P1121 TP Sensor Circuit Intermittent High
Circuit Description
The throttle position (TP) sensor circuit provides voltage
signal that changes relative to the throttle blade angle.
The signal voltage will vary from about 0.6 volts at closed
throttle to about 4.5 volts at wide open throttle (WOT).
The TP signal is one of the most important inputs used by
the powertrain control module (PCM) for fuel control and
for most of the PCM controlled outputs. If the PCM
detects a TP signal that is intermittently above the range
of the TP sensor, DTC P1121 will be set.
Conditions for Setting the DTC
f The ignition is "ON."
f TP sensor indicates a throttle position voltage
intermittently greater than 4.9 volts for a total of 0.15
seconds over a 1.5-second period.
Action Taken When the DTC Sets
f The PCM will not illuminate the malfunction indicator
lamp (MIL).
f The PCM will store conditions which were present
when the DTC was set as Failure Records data only.
This information will not be stored as Freeze Frame
data.
Conditions for Clearing the MIL/DTC
f A history DTC P1121 will clear after 40 consecutive
warm-up cycles have occurred without a fault.
Voltage
f DTC P1121 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 the 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.
Check the ground if these other DTCs are also
set.
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 P1121 cannot be duplicated, reviewing the Failure
Records vehicle mileage since the diagnostic test last
failed may help to determine how often the condition that
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