Fuel System > Engine Control System > P0651 Sensor Reference Voltage \

General Description

The PCM provides a 5volt reference voltage to Throttle Position Sensor 2(TPS2). The PCM monitors reference voltage deviation from the power supply circuit of the sensors.

DTC Description

Checking the voltage from sensor power supply every 1.87 sec. under detecting condition, if the value within detecting condition lasts for more than 0.2 sec., PCM sets P0651. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.

DTC Detecting Condition

Item

Detecting Condition

Possible Cause

DTC Strategy

•	Sensor reference voltage check

•	Short in sensor power supply line

•	Faulty PCM

Enable condition

•

Key "ON"

threshold value

•	Sensor supply power < 4.5V or > 5.5V

diagnosis time

•	Continuous (More than 0.2 seconds failure for every 1.87 seconds test )

MIL ON condition

•	2 driving cycles

Schematic Diagram

Monitor DTC Status

Check DTC Status

(1)	Connect scantool to Data Link Connector(DLC).

(2)

IG "ON".

(3)	Select "DTC" button, and then Press "DTC Status" to check DTC's information from the DTCs menu.

(4)	Read "DTC Status" parameter.

(5)

Is parameter displayed "Present fault"?

	▶ Go to "Terminal and connector inspection" procedure.
	▶ Fault is intermittent caused by poor contact in the sensor's and/or PCM's connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.

Terminal And Connector Inspection

1.	Many malfunctions in the electrical system are caused by poor harness and terminal condition. 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.

Has a problem been found?

	▶ Repair as necessary and go to "Verification of Vehicle Repair" procedure
	▶ Go to "Power Circuit Inspection" procedure.

Power Circuit Inspection

■ Check voltage

1.	IG "OFF" and disconnect ETC Motor & TPS connector.

2.	IG "ON" and ENG "OFF"

Measure voltage between TPS2 power terminal of ETC Motor & TPS harness connector and chassis ground.

Specification : Approx. 5V

Is the measured voltage within specification ?

	▶ Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
	▶ Go to "Check short in harness" as follows.

■ Check short in power harness

IG "OFF".

2.	Disconnect ETC Motor & TPS connector and PCM connector.

3.	Measure the resistance between TPS2 power and ETC motor (+) terminals of ETC Motor & TPS harness connector.(Measurement "A")

4.	Measure the resistance between TPS2 power and ETC motor (-) terminals of ETC Motor & TPS harness connector.(Measurement "A")

5.	Measure the resistance between TPS2 power and TPS1 ground terminals of ETC Motor & TPS harness connector.(Measurement "B")

Measure the resistance between TPS2 power and TPS2 ground terminals of ETC Motor & TPS harness connector.(Measurement "B")

Specification : Infinite

Is the measured resistance within specification ?

	▶ Substitute with a known - good PCM and check for proper operation. If the problem is corrected, replace PCM and go to "Verification of Vehicle Repair" procedure.
	▶ Repair Short in power harness and go to "Verification of Vehicle Repair" procedure.

※ Procedure of ETS Initialization

1. Erase the trouble codes on PCM

2. Turn the ignition key off and keep this condition until the main relay is turned off.(It will take 10 seconds)

3. Turn ignition key on more than 1second to record the throttle motor position on the EEPROM

Verification Of Vehicle Repair

After a repair, it is essential to verify that the fault has been corrected.

1.	Connect scantool and select "DTC" button.

2.	Press "DTC Status" button and confirm that "DTC Readiness Flag" indicates "Completed". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions

3.	Read "DTC Status" parameter

Is parameter displayed "History(Not Present) fault"?

	▶ System performing to specification at this time. Clear the DTC
	▶ Go to the applicable troubleshooting procedure.