See Figures 1, 2, 3 and 4
The TPS is mounted on the throttle body and connected to the throttle blade shaft. The TPS is a variable resistor that provides the engine computer with an input signal (voltage) representing throttle blade position. As the position of the throttle blade changes, the resistance of the TPS changes.
The PCM supplies approximately 5 volts to the TPS. The TPS output voltage (input signal to the PCM) represents throttle blade position. The TPS output voltage to the engine computer varies from approximately 0.5 volts (1 volt for the early Premier and Monaco vehicles) at the minimum throttle opening (idle) to 3.5 volts (4.5 volts for all Premier and Monaco vehicles) at wide open throttle.
Along with inputs from the other sensors, the engine computer uses the TPS input to determine current engine operating conditions. After determining the current operating conditions, the PCM adjusts fuel injector pulse width and ignition timing.
Except Premier and Monaco
- Before replacing the TPS, check the terminals at the TPS and PCM to ensure good connections (tight and clean).
- Turn the ignition switch to the ON position.
Check the output voltage at the orange/dark blue tracer wire of the connector by backprobing the connector with the throttle completely closed (idle). Make certain not to pierce the wire insulation to take a reading, use only the backprobe method.
- If the voltage is 1.0 volt or less with the throttle completely closed, proceed to the next step.
- If the voltage is above 1.0 volt with the throttle completely closed, the TPS is defective and must be replaced with a new one.
While slowly opening the throttle to wide open, watch the voltage reading.
- If the voltage change was a smooth transition, proceed to the next step.
- If the voltage was irregular or no voltage change was detected, the TPS is defective and must be replaced with a new one.
With the throttle completely open (wide open throttle), read the voltage again.
- If the maximum voltage detected was at least 3.5 volts with the throttle completely open, proceed to the next step.
- If the maximum voltage was not 3.5 volts or more, the TPS is defective and must be replaced with a new one.
- The TPS is functioning correctly if it passed all steps in this test.
Premier and Monaco
- Unplug the Throttle Position Sensor (TPS) electrical connector.
- Turn the ignition switch ON .
Measure the voltage between terminals
of the TPS harness connector. The measured voltage should be approximately 5 volts.
- If the measured voltage is within specifications, proceed to Step 4.
- If the measured voltage is not within specifications, inspect the power supply circuitry and wiring using a DRBII scan tool or an equivalent scan tool.
- Turn the ignition switch OFF .
Check for continuity between terminal
- If continuity exists, proceed to Step 6.
- If continuity is not detected, inspect the wire for an open circuit with a DRBII or equivalent scan tool.
- Attach the TPS connectors and turn the ignition switch ON .
Measure the voltage between terminal
and ground. Voltage should be approximately 0.5-1.0 volt.
- If the measured voltage is not within specifications, adjust the sensor and retest.
- If the sensor cannot be adjusted within specifications, replace the sensor with a new one. ADJUSTMENT
Only the Premier and Monaco models have Throttle Position Sensors (TPS) which require adjustment after installation.Premier and Monaco
- A high impedance digital voltmeter (such as C4845 or equivalent) will be needed for this adjustment.
- Turn the ignition key to the ON position.
- Do not unfasten the TPS wire harness connector. Insert the voltmeter test leads through the back of the wire harness connector (back probe them). The TPS terminals are marked A, B and C.
- Check the TPS input voltage at the harness connector. Locate terminal B and insert the negative (-) lead of the voltmeter into it. Insert the positive (+) lead of the voltmeter into the TPS terminal C.
- Note the sensor input voltage on the voltmeter (between terminal B and C).
- Check the TPS output voltage. Disconnect the voltmeter positive (+) from terminal C and connect it to terminal A.
- Note the sensor output voltage on the voltmeter (terminal B and A).
- Divide the output voltage by the input voltage (terminal A+B voltage/ terminal B+C voltage). The resulting out