Throttle Position (Tp) Sensor; Transmission Range Switch; Vehicle Speed Sensor (Vss) - Isuzu 1999 RODEO Workshop Manual

6E1–430 RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
operators foot slipping off of the clutch with the vehicle
being revved up and in gear.
5. A/C should always be turned OFF before performing
the TEC learn procedure.
6. A Class II command from the Tech 2 is required to
invoke the TEC learn procedure.
7. No Camshaft and/or Crankshaft Sensor DTC Codes
present.
Tooth Error Learn Procedures
The following steps are required to learn the tooth error
once the above mentioned
requirements are met:
1. Make sure that the tooth error learn procedure has
been invoked with the Tech 2, other wise when the
throttle is depressed, the RPM would go to the high
RPM fuel cutoff and not be cutoff at the lower tooth
error learning fuel cutoff limit.
2. Depress the brake pedal for safety reasons.
3. Depress the throttle pedal to Wide Open Throttle
(WOT) and keep the throttle at 100% for the duration
of the Tooth Error Correction (TEC) learning process
until the TEC is learned or the number of attempts to
learn has been exceeded. The RPM will be limited to
the upper TEC RPM limit until one of the two above
mentioned conditions are met and the throttle is
released to less than 5% Throttle Position Sensor
(TPS). After this, the RPM limit will be the normal
redline RPM limit.
4. The tooth error learning diagnostic will learn the tooth
error as the engine decelerates in fuel cutoff.
5. During the tooth error learning procedure. TEC
specific information is available which will indicate
that the tooth error was properly learned and
completed.
Considerations For Locating The Tooth Error
Learning Procedure
The area that the tooth error learn is done should be well
ventilated or have vehicle exhaust elimination system
which attaches to the tail pipe and draws the vehicle
exhaust out of the building.
CAUTION: Appropriate safety measures should be
taken to assure the safest conditions possible for all
those people in the nearby vicinity of where the tooth
error learn procedure is being performed. If possible,
anchored or secured safety barriers should be in
place in at least the front of the vehicle and in the
back of the vehicle if possible to reduce the
possibility of accidents. The figure below shows the
proper placement of a frontal safety barrier.
The area that the tooth error learn is done should be
well ventilated or have vehicle exhaust elimination
system which attaches to the tail pipe and draws the
vehicle exhaust out of the building.

Throttle Position (TP) Sensor

The throttle position (TP) sensor is a potentiometer
connected to the throttle shaft on the throttle body. The
vehicle preparation
PCM monitors the voltage on the signal line and
calculates throttle position. As the throttle valve angle is
changed (accelerator pedal moved), the TP sensor signal
also changes. At a closed throttle position, the output of
the TP sensor is about 0.25 volts. As the throttle valve
opens, the output increases so that at wide open throttle
(WOT), the output voltage should be about 4.75 volts.
The PCM calculates fuel delivery based on throttle valve
angle (driver demand). A broken or loose TP sensor may
cause intermittent bursts of fuel from an injector and
unstable idle because the PCM thinks the throttle is
moving. A hard failure in the TP sensor 5–volt reference
or signal circuits will set either a DTC P0122 or DTC
P0123. A hard failure with the TP sensor ground circuit
may set DTC P0123 and DTC P0122. Once a DTC is set,
the PCM will use an artificial default value based on
engine RPM and mass air flow for the throttle position,
and some vehicle performance will return. A high idle may
result when either DTC P0122 or DTC P0123 is set. The
PCM can detect intermittent TP sensor faults. DTC
P1121 or DTC P1122 will set if an intermittent high or low
circuit failure is being detected.

Transmission Range Switch

IMPORTANT: The vehicle should not be driven with the
transmission range switch disconnected; idle quality will
be affected.
The four inputs from the transmission range switch
indicate to the PCM which position is selected by the
transmission selector lever. This information is used for
ignition timing, EVAP canister purge, EGR and IAC valve
operation.
For more information on the transmission range switch,
refer to 4L30–E Automatic Transmission.

Vehicle Speed Sensor (VSS)

The PCM determines the speed of the vehicle by
converting a pulsing voltage signal from the vehicle speed
101RX003