Diagnostic Procedure
CAUTION:
To prevent damage to scan tool, always turn the ignition off before connecting or disconnecting scan tool.
- Install scan tool. Turn ignition on. Check for DTCs. Turn ignition off. Is DTC 11 or 12 present? If so, see DTC 11: THROTTLE POSITION SENSOR CIRCUIT - SHORTED and/or DTC 12: THROTTLE POSITION SENSOR CIRCUIT - OPEN . If not, go to next step.
- Turn ignition on. Using scan tool, monitor TP sensor. With throttle in idle position, voltage should be 0.3-1.0 volt on 3.0L models and 0.535-0.735 volt on 3.5L models. With throttle in fully opened position, voltage should be 4.5-5.5 volts on both models. Turn ignition off. Is the voltage as specified? If so, malfunction is intermittent. If not, go to next step.
- Check TP sensor output voltage at TP sensor harness connector by backprobing. Do not disconnect TP sensor harness connector. Turn ignition on. Measure voltage between TP sensor harness connector terminal No. 3 and ground. With throttle in idle position, voltage should be 0.3-1.0 volt on 3.0L models and 0.535-0.735 volt on 3.5L models. With throttle in fully opened position, voltage should be 4.5-5.5 volts on both models. Turn ignition off. Is the voltage as specified? If so, go to next step. If not, go to step 8 .
- Check TP sensor output voltage at PCM harness connector by backprobing. Do not disconnect PCM harness connector. Turn ignition on. Measure voltage between PCM harness connector terminal No. 78 and ground. With throttle in idle position, voltage should be 0.3-1.0 volt on 3.0L models and 0.535-0.735 volt on 3.5L models. With throttle in fully opened position, voltage should be 4.5-5.5 volts on both models. Turn ignition off. Is the voltage as specified? If so, go to next step. If not, go to step 7 .
- Check TP sensor and PCM harness connectors for damage. Are the harness connectors in good condition? If so, go to next step. If not, repair or replace the defective harness connector(s).
- Turn ignition on. Using scan tool, monitor TP sensor. With throttle in idle position, voltage should be 0.3-1.0 volt on 3.0L models and 0.535-0.735 volt on 3.5L models. With throttle in fully opened position, voltage should be 4.5-5.5 volts on both models. Turn ignition off. Is the voltage as specified? If so, malfunction is intermittent. If not, possible faulty PCM exists. Replace the PCM if necessary. See POWERTRAIN CONTROL MODULE under REMOVAL & INSTALLATION.
- Check TP sensor and PCM harness connectors for damage. Are the harness connectors in good condition? If so, repair open or damage in wire harness between TP sensor harness connector terminal No. 3 and PCM harness connector terminal No. 78. If not, repair or replace the defective harness connector(s).
- Check the power supply voltage at TP sensor harness connector by backprobing. Do not disconnect TP sensor harness connector. Turn ignition on. Measure voltage between TP sensor harness connector terminal No. 4 and ground. Voltage should be 4.9-5.1 volts. Turn ignition off. Is the voltage as specified? If so, go to step 13 . If not, go to next step.
- Check the power supply voltage at PCM harness connector by backprobing. Do not disconnect PCM harness connector. Turn ignition on. Measure voltage between PCM harness connector terminal No. 46 and ground. Voltage should be 4.9-5.1 volts. Turn ignition off. Is the voltage as specified? If so, go to next step. If not, go to step 11 .
- Check TP sensor and PCM harness connectors for damage. Are the harness connectors in good condition? If so, repair open or damage in wire harness between TP sensor harness connector terminal No. 4 and PCM harness connector terminal No. 46. If not, repair or replace the defective harness connector(s).
- Check TP sensor and PCM harness connectors for damage. Are the harness connectors in good condition? If so, go to next step. If not, repair or replace the defective harness connector(s).
- Check wire harness for short to ground between TP sensor harness connector terminal No. 4 and PCM harness connector terminal No. 46. Is the wire harness in good condition? If so, go to step 6 . If not, repair wire harness as necessary.
- Check the ground voltage at TP sensor harness connector by backprobing. Do not disconnect TP sensor harness connector. Turn ignition on. Measure voltage between TP sensor harness connector terminal No. 1 and ground. Voltage should be 0.5 volt or less. Turn ignition off. Is the voltage as specified? If so, go to step 17 . If not, go to next step.
- Check the ground voltage at PCM harness connector by backprobing. Do not disconnect PCM harness connector. Turn ignition on. Measure voltage between PCM harness connector terminal No. 57 and ground. Voltage should be 0.5 volt or less. Turn ignition off. Is the voltage as specified? If so, go to next step. If not, go to step 16 .
- Check TP sensor and PCM harness connectors for damage. Are the harness connectors in good condition? If so, repair open or damage in wire harness between TP sensor harness connector terminal No. 1 and PCM harness connector terminal No. 57. If not, repair or replace the defective harness connector(s).
- Check PCM harness connectors for damage. Are the harness connectors in good condition? If so, go to step 6 . If not, repair or replace defective harness connector(s).
- Check TP sensor harness connector for damage. Is the harness connector in good condition? If so, go to next step. If not, repair or replace defective harness connector.
- Check the TP sensor. Disconnect TP sensor harness connector and measure at the sensor side. Measure the resistance between TP sensor terminals No. 1 and 4. Resistance should be 3.5-6.5 k/ohms. Then measure resistance between TP sensor terminals No. 1 and 3 while moving the throttle from idle position to fully opened position. Resistance should change smoothly in proportion to opening angle of the throttle. Is the resistance of both measurements as specified? If so, go to next step. If not, replace TP sensor.
- Check PCM harness connectors for damage. Are the harness connectors in good condition? If so, go to next step. If not, repair or replace the defective harness connector(s).
- Check wire harness for short to ground or damage between TP sensor harness connector terminal No. 3 and PCM harness connector terminal No. 78. Is the wire harness in good condition? If so, go to next step. If not, repair wire harness as necessary.
- Check the wire harness for short to ground between TP sensor harness connector and the auto-cruise control ECU connector. Is the wire harness in good condition? If so, adjust TP sensor. If not, repair wire harness.