P0068
DTC P0068
GENERAL DESCRIPTION
The Throttle Position Sensor (TPS) is mounted on the throttle body and detects the opening angle of the throttle plate.The TPS has a variable resistor (potentiometer) whose characteristic is the resistance changing according to the throttle angle. During acceleration, the TPS resistance between the reference 5 V and the signal terminal decreases and output voltage increases; during deceleration, the TPS resistance increases and TPS output voltage decreases.The ECM/PCM supplies a reference 5 V to the TPS and the output voltage increases directly with the opening of the throttle valve. The TPS output voltage will vary from 0.2-0.8 V at closed throttle to 4.3-4.8 V at wide-open throttle.The ECM/PCM determines operating conditions such as idle (closed throttle), part load, acceleration/deceleration, and wide-open throttle from the TPS. Also The ECM/PCM uses the Mass Air Flow Sensor (MAFS) or Manifold Absolute Pressure Sensor (MAPS) signal along with the TPS signal to adjust fuel injection duration and ignition timing.
DTC DESCRIPTION
If the sensor input value of TPS is lower or higher than the threshold value which is depending on MAF more 300 sec, ECM/PCM sets DTC P0068.
DTC Detecting Condition:
SPECIFICATION
ITEM SPECIFICATION
TPS Resistance (ohm) 1.6 - 2.4 kohms at 20 °C (68 °F)
Schematic Diagram - A/T:
Schematic Diagram - M/T:
Signal Waveform And Data:
MONITOR SCANTOOL DATA
1. Connect scantool to Data Link Connector(DLC).
2. Warm up the engine to normal operating temperature.
3. Monitor the "TPS and MAFS" parameters on the scantool.
4. Is parameter displayed within specifications?
YES - Fault is intermittent caused by poor contact in the sensor's and/or ECM's connector or was repaired and ECM/PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of vehicle Repair" procedure.
NO - Go to "Terminal and Connector Inspection" procedure.
TERMINAL AND CONNECTOR INSPECTION
1. Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?
YES - Repair as necessary and go to "Verification of vehicle Repair" procedure.
NO - Go to "Component inspection" procedure.
COMPONENT INSPECTION
1. Check TPS.
a. Ignition "OFF".
b. Disconnect TPS connector.
c. Measure resistance terminal 2 and 3 of TP sensor connector(Component side).
Specification :
ITEM Specification
TPS Resistance (kohms) 1.6 - 2.4 kohms at 20 °C(68 °F)
d. Is the measured resistance within specifications?
YES - Go to "Check ECM/PCM" as below.
NO - Check TPS for contamination, deterioration, or damage. Substitute with a known - good TPS and check for proper operation. If the problem is corrected, replace TPS and then go to "Verification of Vehicle Repair" procedure.
2. Check ECM/PCM.
a. Key "OFF". (Don't disconnect sensors.)
b. Select "vehicle scopemeter" in the menu, and connect channel A of scantool with terminal 1 of TPS harness connector.
c. Connect channel B of scantool with terminal 3 of MAFS harness connector.
d. Engine start. And check the signal waveforms with stepping on accelerator pedal.
e. Is the signal waveform within specifications?
YES - Substitute with a known - good ECM/PCM and check for proper operation. If the problem is corrected, replace ECM/PCM and then go to "Verification of Vehicle Repair" procedure.
NO - Substitute the sensor which outputs abnormal waveform with a known - good sensor and check for proper operation. If the problem is corrected, replace the sensor and then go to "Verification of Vehicle Repair" procedure.
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode.
2. Clear the DTCs and Operate the vehicle within DTC Enable conditions in General information.
3. Are any DTCs present ?
YES - Go to the applicable troubleshooting procedure.
NO - System is performing to specification at this time.