Test Procedure

WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2005 Mercury Sable, 2005 Mercury Mountaineer, 2005 Mercury Monterey, 2005 Mercury Montego, and 2005 Mercury Mariner. However, it is still accessible from the selected car via links, so may be relevant.

QA1 CARRY OUT A VEHICLE INSPECTION AND VERIFY THE SELF-TEST PROCEDURE

NOTE: If the self-test or communication concern occurred after a failed or an aborted reprogram, the module may be blank. Attempt to reprogram the module again before continuing with this pinpoint.

This pinpoint test addresses the following concerns:
- unable to communicate with PCM.
- unable to activate the PCM self-test.
Possible causes:
- incorrect self-test procedure.
- communication circuit open from PCM to the DLC.
- PCM power or ground circuits PCM.
- VREF circuit short to ground (Excursion, Explorer Sport Trac, Ford GT, Freestar/Monterey, or Ranger).
Visually inspect the following for obvious signs of electrical damage:
- harness wiring.
- electrical connections.
Verify the correct procedure was used to activate the self-test for the diagnostic tool. REFER to DIAGNOSTIC TOOL SETUP AND FUNCTIONALITY .

Was the correct self-test procedure used?

Yes	No
GO to QA2.	REFER to DIAGNOSTIC TOOL SETUP AND FUNCTIONALITY .

QA2 CARRY OUT THE DATA LINK DIAGNOSTICS TEST

Connect the diagnostic tool.
Key in ON position.
Carry out the data link diagnostics test.

Is system passed obtained?

Yes	No
GO to QT1 CARRY OUT THE PCM QUICK TEST .	For all electronic control units no response/not equipped, GO to QA3. For PCM no response/not equipped, GO to QA3. For no response from the diagnostic tool, REFER to MODULE COMMUNICATIONS NETWORK to diagnose no response from the diagnostic tool.

QA3 CHECK FOR VREF VOLTAGE AT A SENSOR

NOTE: PCM power and ground can be determined by measuring VREF voltage at a sensor. Refer to the PCM COMMUNICATION PROTOCOL AND VREF INFORMATION TABLE table at the beginning of this pinpoint test for the vehicle application and the applicable sensor to test.

Key in OFF position.
Disconnect the applicable sensor.
Key in ON position.
Measure the voltage between the applicable sensor VREF circuit, harness side and the applicable sensor SIGRTN circuit, harness side.

Is the voltage between 4.5 volts - 5.5 volts?

Yes	No
For Excursion, Explorer Sport Trac, Ford GT, Freestar/Monterey, or Ranger, GO to QA6. For all others, REFER to MODULE COMMUNICATIONS NETWORK to diagnose no communication with the PCM.	GO to QA4.

QA4 CHECK THE PCM VPWR CIRCUITS FOR VOLTAGE

Key in OFF position.
Disconnect the PCM.
Key in ON position.

Measure the voltage between:

(+) PCM Connector, Harness Side	(-)
VPWR	Ground

Are the voltages greater than 10.5 volts?

Yes	No
GO to QA5.	GO to B1 .

QA5 CHECK THE PCM GROUND CIRCUITS FOR AN OPEN

Key in OFF position.

Measure the resistance between:

(+) PCM Connector, Harness Side	(-)
PWRGND	Ground

Are the resistances less than 5 ohms?

Yes	No
For Excursion, Explorer Sport Trac, Ford GT, Freestar/Monterey, or Ranger, GO to Pinpoint Test C step 1 . For all others, GO to QA7.	REPAIR the open circuit.

QA6 CHECK COMMUNICATION WITH THE SUSPECT SENSOR DISCONNECTED

Key in ON position.
Carry out the data link diagnostics test.
Key in OFF position.
Reconnect the suspect sensor.
Carry out the data link diagnostics test.

Is PCM communication present only when the sensor is disconnected?

Yes	No
INSTALL a new suspect sensor.	REFER to MODULE COMMUNICATIONS NETWORK to diagnose no communication with the PCM.

QA7 CHECK FOR CORRECT PCM OPERATION

Disconnect all the PCM connectors.
Visually inspect for:
- corrosion.
- pushed out pins.
Connect all the PCM connectors and make sure they seat correctly.
Carry out the data link diagnostic test and verify the concern is still present.

Is the concern still present?

Yes	No
INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) .	The system is operating correctly at this time. Concern may have been caused by a loose or corroded connector.