Fuel System > Engine Control System > P0268 Cylinder 3 Injector Circuit High

Component Location

General Description

Based on information from various sensors, the PCM calculates the fuel injection amount. The fuel injector is a solenoid-operated valve and the fuel injection amount is controlled by length of time the fuel injector is held open. The PCM controls each injector by grounding the control circuit. When the PCM energizes the injector by grounding the control circuit, the circuit voltage should be low (theoretically 0V) and the fuel is injected. When the PCM de-energizes the injector by opening the control circuit, the fuel injector is closed and circuit voltage should momentarily peak.

DTC Description

Checking output signals from injectors under detecting condition, if an output signal is high, PCM sets P0268. MIL (Malfunction Indication Lamp) turns on when the malfunction lasts till continuous 2 driving cycle.

DTC Detecting Condition

Item

Detecting Condition

Possible Cause

DTC Strategy

•	Signal High

•	Poor connection

•	Short to battery in harness

•

Injector

•

PCM

Enable condition

•	Engine running

•	11V ≤ Battery voltage ≤ 16V

•	No disabling faults present

•	Above conditions are met > 0.5sec.

threshold value

•	Short to battery

diagnosis time

•	Continuous

MIL ON condition

•	2 driving cycles

Specification

Item	Coil resistance(Ω)
Injector	11.4 ~ 12.6Ω ( at 20°C/ 68°F)

Schematic Diagram

Signal Wavefrom And Data

When the PCM energizes the injector by grounding control circuit, the circuit voltage should be low (theoretically 0V) and the fuel is injected. When the PCM de-energizes the injector by opening control circuit, the fuel injector is closed and circuit voltage should momentarily peak.

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 "Control Circuit Inspection" procedure.

Control Circuit Inspection

■ Check voltage

1.	IG "OFF" and disconnect injector connector.

2.	IG "ON" and ENG "OFF"

Measure voltage between injector control terminal of injector harness connector and chassis ground.

Specification : Approx. 0V

Is the measured voltage within specification?

	▶ Go to "Component Inspection" procedure.
	▶ Go to "Check short to battery in harness" as follows.

■ Check short to battery in harness

1.	IG "OFF" and disconnect injector connector and PCM connector.

Measure resistance between power and control terminals of injector harness connector.

Specification : Infinite

Is the measured resistance within specification?

	▶ Go to "Component Inspection" procedure.
	▶ Repair short to battery in harness, and go to "Verification of Vehicle Repair" procedure.

Component Inspection

■ Check injector

1.	IG "OFF" and disconnect injector connector.

Measure resistance between power and control terminals of injector connector.(Component side)

Specification : 11.4 ~ 12.6Ω ( at 20°C/ 68°F)

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

There is a memory reset function on scantool that can erase optional parts automatically detected and memorized by PCM. After testing PCM on the vehicle, use this function to reuse the PCM on the others

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.