Test Procedure

QA1 VEHICLE INSPECTION AND VERIFY THE SELF-TEST PROCEDURE

This pinpoint test addresses the following concerns:
- Unable to communicate with PCM.
- Unable to activate the PCM self-test.
- Scan tool communication concern.
Possible causes:
- Damaged DLC.
- Incorrect self-test procedure.
- Open DLC harness circuit.
- Short in the DLC harness circuit or associated modules.
- Damaged power or ground circuits to PCM.
- Damaged PCM.
NOTE: If the self-test or communication concern only occurred after a failed or aborted module reprogram, the module may be blank. If this is the case, try reprogramming the module again before continuing with this pinpoint test.
Visually inspect for obvious signs of electrical damage.
Inspect:
- Power distribution box fuses.
- Smart junction box fuses.
- Harness wiring.
- Electrical connections.
REPAIR/REPLACE as necessary.
Verify the correct procedure was used to activate the self-test for the scan tool. REFER to DIAGNOSTIC METHODS - CNG, FLEX-FUEL & GASOLINE , Diagnostic Methods.

Was the correct self-test procedure used?

Yes	No
KEY OFF GO to QA2.	KEY OFF Correct procedure was not used for activating Self-Test RETURN to QT: STEP 1: PCM QUICK TEST , and CARRY OUT the self-test using the correct procedure.

QA2 INSPECT THE VEHICLE AND SCAN TOOL DLC FOR DAMAGE

Disconnect the scan tool.
INSPECT the vehicle and scan tool DLC for damage.

NOTE: CHECK the DLC circuit(s) for corrosion or loose wires.

Are there any concerns with the wiring or the DLC connection?

Yes	No
Repair as necessary.	GO to QA3.

QA3 CHECK THE B+ VOLTAGE TO THE DATA LINK CONNECTOR (DLC)

Scan tool disconnected.
Measure the voltage between:

( + )DLC Connector, Harness Side	( - )12V vehicle battery
B+ - Pin 16	Negative terminal

Is the voltage greater than 10.5 V?

Yes	No
GO to QA4.	REPAIR open circuit.

QA4 CHECK THE DLC CHASSIS GROUND CIRCUIT FOR AN OPEN IN THE HARNESS

Measure the voltage between:

( + )DLC Connector, Harness Side	( - )DLC Connector, Harness Side
B+ - Pin 16	CHGND - Pin 4

Is the voltage greater than 10.5 V?

Yes	No
GO to QA5.	REPAIR open circuit.

QA5 CHECK THE DLC POWER GROUND CIRCUIT FOR AN OPEN IN THE HARNESS

Measure the voltage between:

( + )DLC Connector, Harness Side	( - )DLC Connector, Harness Side
B+ - Pin 16	PWRGND - Pin 5

Is the voltage greater than 10.5 V?

Yes	No
GO to QA6.	REPAIR open circuit.

QA6 RUN THE DATA LINK DIAGNOSTIC NETWORK TEST

NOTE: The purpose of this test step is to determine if the scan tool can communicate to the PCM by using the Network Test function on the scan tool. The Network Test pings each module on the network and looks for a reply. If a PCM communication error message is encountered possible causes are:

Loss or intermittent loss of power or ground to the PCM.
PCM VREF circuit concern causing a PCM reset.
PCM to network communication problems (open or shorted data link (+) or (-) circuit from the PCM to the rest of the network modules or DLC).

Connect the scan tool.
Key ON Engine OFF.
Run the Data Link Diagnostic Network Test.

NOTE: Typical PCM network error messages:

PCM : No Response/Not Equipped.
PCM: No Response on Bus +.
PCM: No Response on Bus -.
PCM : No Response on HS-CAN(+).
PCM : No Response on HS-CAN(-).

Are there any PCM network error messages?

Yes	No
CHECK to see if the PCM is receiving power and ground. PCM power and ground can be established by measuring VREF voltage at 1 of the following components. To find the VREF measurement point, refer to the PCM COMMUNICATION NETWORK AND VREF INFORMATION TABLE found at the beginning of this pinpoint test. Select the applicable GO TO for the VREF to be measured. For Throttle Position (TP) Sensor GO to QA7 For Fuel Rail Pressure (FRP) Sensor GO to QA8 For Fuel Rail Pressure Temperature (FRPT) Sensor GO to QA9.	PCM network test passed GO to QA11.

Yes

CHECK to see if the PCM is receiving power and ground. PCM power and ground can be established by measuring VREF voltage at 1 of the following components. To find the VREF measurement point, refer to the PCM COMMUNICATION NETWORK AND VREF INFORMATION TABLE found at the beginning of this pinpoint test. Select the applicable GO TO for the VREF to be measured.
For Throttle Position (TP) Sensor
GO to QA7
For Fuel Rail Pressure (FRP) Sensor
GO to QA8
For Fuel Rail Pressure Temperature (FRPT) Sensor
GO to QA9.

PCM network test passed
GO to QA11.

QA7 CHECK THE VREF VOLTAGE TO TP SENSOR

NOTE: This test step determines if the PCM has power and ground.

TP Sensor connector disconnected.
Key ON Engine OFF.
Measure the voltage between:

( + )TP Sensor Connector, Harness Side	( - )TP Sensor Connector, Harness Side
VREF	SIGRTN

Is the voltage between 4 V - 6 V?

Yes	No
PCM has power and ground GO to QA10.	GO to PINPOINT TEST C step 1 .

QA8 CHECK THE VREF VOLTAGE TO THE FRP SENSOR

NOTE: This test step determines if the PCM has power and ground.

FRP Sensor connector disconnected.
Key ON Engine OFF.
Measure the voltage between:

( + )FRP Sensor Connector, Harness Side	( - )FRP Sensor Connector, Harness Side
VREF	SIGRTN

Is the voltage between 4 V - 6 V?

Yes	No
PCM has power and ground GO to QA10.	GO to PINPOINT TEST C step 1 .

QA9 CHECK THE VREF VOLTAGE TO THE FRPT SENSOR

NOTE: This test step determines if the PCM has power and ground.

FRPT Sensor connector disconnected.
Key ON Engine OFF.
Measure the voltage between:

(+) FRPT Sensor Connector, Harness Side	(-) FRPT Sensor Connector, Harness side
VREF -Pin 2	SIGRTN - Pin 4

Is the voltage between 4 V - 6 V?

Yes	No
PCM has power and ground GO to QA10.	GO to PINPOINT TEST C step 1 .

QA10 CHECK THE LINK COMMUNICATION WITH THE VREF SENSOR DISCONNECTED

With the measured VREF sensor from the previous step still disconnected.
Scan Tool Connected.
Key ON Engine OFF.
Attempt to access the FRP, FRPT, or TP voltage PID.
NOTE: If the PID cannot be accessed or scan tool communication problems still exist, GO to the appropriate MODULE COMMUNICATIONS NETWORK article for further diagnosis.
Reconnect the sensor while monitoring the PID.

Does PCM to scan tool communication error occur only when the VREF sensor is reconnected?

Yes	No
VREF shorted to SIGRTN in the sensor, replace suspect sensor.	PCM has power and ground. If scan tool communication problems continue: REFER to the appropriate MODULE COMMUNICATIONS NETWORK article for further diagnosis Otherwise return to the section or pinpoint that sent you here.

QA11 CHECK THE OTHER ECU(S) FOR NETWORK ERROR MESSAGES

Using previous network test results.
CHECK the other ECU(s) for network error messages.

NOTE: Ignore optional equipment modules communication errors unless the module is related to the symptom being diagnosed.

Are there any ECU network error messages?

Yes	No
Other ECU network errors encountered REFER to the appropriate MODULE COMMUNICATIONS NETWORK article for further diagnosis	Test Complete Return to the Symptom Chart or section for the module in question.

QA12 KOER DTC P1001: KOER NOT ABLE TO COMPLETE. KOER ABORTED

Verify the correct procedure was used to activate the self-test for the scan tool. REFER to DIAGNOSTIC METHODS - CNG, FLEX-FUEL & GASOLINE , Diagnostic Methods.

Was the correct self-test procedure used?

Yes	No
GO to QA13.	Correct procedure was not used for activating Self -Test RETURN to QT: STEP 1: PCM QUICK TEST , and CARRY OUT the self-test using the correct procedure.

QA13 CHECK FOR ANY OTHER KOER DTCS

Are there any other KOER DTCs?

Yes	No
GO to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS for pinpoint test direction. REPAIR the other DTCs first.	GO to QA14.

QA14 CHECK FOR ANY OTHER PCM DTCS

Are there any other PCM DTCs?

Yes	No
GO to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS for pinpoint test direction. REPAIR the other DTCs first.	GO to STEP 2: NO DTC(S) PRESENT SYMPTOM CHART INDEX for direction to the proper Step 3 Chart NOTE: If the symptom is not listed, REFER to the appropriate service information article or GO to PINPOINT TEST Z step 1 for intermittent system diagnostics