Introduction

NOTE: The descriptions and specifications contained in this information were in effect at the time it was approved for publication. Ford Motor Company reserves the right to discontinue models at any time, or change specifications or design without notice and without incurring obligation.

Important Safety Notice
Appropriate service methods and procedures are essential for the safe, reliable operation of all motor vehicles as well as the personal safety of the individual doing the work. This information provides general directions for performing service with tested, effective techniques. Following them will help assure reliability.

There are numerous variations in procedures, techniques, tools, and parts for servicing vehicles, as well as in the skill of the individual doing the work. This information cannot possibly anticipate all such variations and provide advice or cautions as to each. Accordingly, anyone who departs from the instructions provided must first establish that he compromises neither his personal safety nor the vehicle integrity by his choice of methods, tools or parts.

Notes, Cautions, and Warnings
As you read through the procedures, you will come across NOTES, CAUTIONS, and WARNINGS. Each one is there for a specific purpose. NOTES give you added information that will help you to complete a particular procedure. CAUTIONS are given to prevent you from making an error that could damage the vehicle. WARNINGS remind you to be especially careful in those areas where carelessness can cause you personal injury. The following list contains some general WARNINGS that you should follow when you work on a vehicle.
^ Always wear safety glasses for eye protection.
^ Use safety stands whenever a procedure requires you to be under the vehicle.
^ Make sure that the ignition switch is always in the OFF position, unless otherwise required by the procedure.
^ Set the parking brake when working on the vehicle. If you have an automatic transmission, set it in PARK unless instructed otherwise for a specific operation. If you have a manual transmission, it should be in REVERSE (engine OFF) or NEUTRAL (engine ON) unless instructed otherwise for a specific operation. Place wood blocks (4" x 4" or larger) against the front and rear surfaces of the tires to help prevent the vehicle from moving.
^ Operate the engine only in a well-ventilated area to avoid the danger of carbon monoxide poisoning.
^ Keep yourself and your clothing away from moving parts when the engine is running, especially the drive belts.
^ To prevent serious burns, avoid contact with hot metal parts such as the radiator, exhaust manifold, tail pipe, three-way catalytic convener, and muffler.
^ Do not smoke while working on a vehicle.
^ To avoid injury, always remove rings, watches, loose hanging jewelry, and loose clothing before beginning to work on a vehicle.
^ When it is necessary to work under the hood, keep hands and other objects clear of the radiator fan blades!

Preface
This information provides a step-by-step approach for diagnosing driveability, emission and powertrain control system symptoms. Before beginning diagnosis, it may be helpful to reference any Technical Service Bulletins (TSBs) or On-line Automotive Service Information System (OASIS) information when this is available.

NOTE: For 6.0L diesel, 7.3L diesel and Bi-Fuel, go to the 6.0L DIESEL, 7.3L DIESEL or BI-FUEL tab.

This information is used in conjunction with the Body, Chassis, Electrical, Powertrain Vehicle Systems, and the Vehicle/Diagrams. The Vehicle Systems information are used to provide additional diagnostics when directed by these procedures. The Vehicle Systems are also used for component removal and replacement information. Refer to the Vehicle/Diagrams for vehicle specific wiring information and component, connector and splice location.

The following is a description of the information contained for diagnosis.

Description And Operation
Description And Operation contains description and operation information on powertrain control systems and components. It is designed to give the technician a general knowledge of the powertrain control system. It should be used when general information about the powertrain control system is desired, and is rarely referenced from other Vehicle Systems.

Diagnostic Methods
The Diagnostic Methods contains information on specific diagnostic tasks that are used during diagnosis. Descriptions of specific diagnostic methods are included, as well as detailed instructions on how to access or perform the tasks. It provides the technician with step-by-step instructions for performing routine diagnostic tasks.

Symptom Charts
All diagnosis begins in Symptom Charts with Step 1: Powertrain Control Module (PCM) Quick Test. If the PCM Quick Test is completed and no Diagnostic Trouble Codes (DTCs) are received, the technician may be directed to Step 2: No DTCs Present Symptom Chart Index (refer to Symptom Charts for details). The No DTCs Present Symptom Chart Index contains the list of symptoms addressed in this information, and will send the technician to the appropriate Step 3: No DTCs Present Symptom Chart. If no PCM DTCs are present and the vehicle symptom is not listed in the Step 2: No DTCs Present Symptom Chart Index, the technician should go the appropriate Vehicle System to continue diagnosis.

Powertrain DTC Charts and Description
Powertrain DTC Charts and Description contains the Powertrain Diagnostic Trouble Code (DTC) "Go To" Charts. These charts will be referenced if a DTC is received in Symptom Charts. Also included in this system are the Powertrain DTC descriptions and list of possible causes.

Pinpoint Tests
All pinpoint tests are included in Pinpoint Tests. Never enter a Pinpoint Test unless directed there. When directed to a Pinpoint Test, always read the information and look at the schematic included at the beginning of the Pinpoint Test.

Reference Values
Reference Values contains the "Typical Diagnostic Reference Values" charts. The technician will be directed to these charts from Pinpoint Test Z in Pinpoint Tests.

How To Use The Diagnostic Procedures
^ Use the information about the vehicle driveability or emission concern to attempt to verify/re-create the symptom. Look for any vehicle modifications or aftermarket items that may contribute to the symptom. A check of any applicable TSBs or OASIS messages may be useful, if this information is available.
^ Go to Symptom Charts, Step 1: PCM Quick Test. Perform the PCM Quick Test step(s). Follow any notes as directed.
^ If PCM Quick Test is completed, no DTCs were received and no special notes applied, go to Step 2: No DTCs Present Symptom Chart Index.
^ Select the symptom that best describes the vehicle symptom (for multiple symptoms select the one that is most noticeable). Go to the Step 3: No DTCs Present Symptom Chart that is indicated. If no PCM DTCs are present and the vehicle's symptom is not listed in the No DTCs Present Symptom Chart Index, go to the appropriate Vehicle System to continue diagnosis.
^ The No DTCs Present Symptom Chart contains areas to be tested for diagnosis of the vehicle's symptom. The chart is arranged to place the higher probability, or easiest to test items toward the top of the chart. The technician, however, is not required to follow this order due to reasons such as variations in vehicle type, vehicle repair history or technician experience.
- The System/Component column indicates the areas that will be tested. This column may also contain a quick system/component test.
- The Reference column indicates where to go for the System/Component testing. All references are to pinpoint test steps in Pinpoint Tests unless noted otherwise. If referenced to a Pinpoint Test Step, go to the procedures. Follow the directions given in those procedures, including directions to other tests or Vehicle Systems. If a damaged part is found, repair/replace as directed. If no fault is found, and diagnosis in that area is complete, return to the No DTCs Present Symptom chart and continue to the next item.
- If a quick system/component test is in the System/Component column, the reference column will indicate where to go if the test failed.
^ During diagnosis, if directed to test a system/component that is not contained on that vehicle, proceed to the next step.
^ If the No DTCs Present Symptom Chart for the vehicle symptom is completed and no fault is found, return to Step 2: No DTCs Present Symptom Chart Index to address the next most prominent symptom. If all diagnosis is complete and no fault is found, it may be helpful to go to Pinpoint Tests, Pinpoint Test Step Z1, for further diagnosis.
^ After service, restore vehicle by reconnecting any components, removing test equipment, etc. Verify that the vehicle is operating properly and the original complaint is eliminated. If a DTC was present, rerun Quick Test to verify repair and complete a PCM Reset to clear any Continuous Memory DTCs.

Customer Information Worksheet:

NOTE: If a symptom is determined to be intermittent, careful visual and physical underhood inspection of connectors, wiring harnesses, vacuum lines, components, etc. is required. The Customer Information Worksheet may contain more detailed symptom information. Before an in-depth diagnosis begins, start the engine and wiggle wires, tap on components, etc., while listening for an indication of a concern (such as rpm change or relay clicking).

Information about engine conditions is stored when a Diagnostic Trouble Code (DTC) that lights the Malfunction Indicator Lamp (MIL) is set. This information is called Freeze Frame Data and may be helpful in diagnosing intermittents. (Refer to Diagnostic Methods, Freeze Frame Data, for more information.)

What's New In This Vehicle Systems
The following is a list of changes for 2003:

New Components/Systems (see Description And Operation for description):
^ EGR system module (ESM)
^ Variable speed electric cooling fan (introduced on Crown Victoria/Grand Marquis, Thunderbird, LS6/LS8 and Town Car)

New Vehicles:
^ Mercury Marauder (4.6L 4V) (unless specifically called out, follow Grand Marquis direction in Vehicle System for the Marauder)
^ Mustang Mach I with 4.6L 4V
^ Lincoln Aviator (with 4.6L 4V and 150 pin PCM)

Deleted Vehicles:
^ Cougar
^ Continental
^ Villager (was covered under separate tab in Vehicle System)

Other Changes
^ Mustang Cobra with 4.6L 4V SC
^ Focus with 2.3L
^ 122 pin PCM introduced on Expedition and Navigator.
^ New SAE DTCs included. For 2003, some manufacturer specific DTCs (P1xxx) are being changed to SAE defined DTCs (P0xx). The PCM software that sets the DTC remains the same.
^ EGR System Module (ESM) pinpoint test HH added to Pinpoint Tests.
^ Variable Speed Electric Cooling Fan pinpoint test KN added to Pinpoint Tests.
^ Link/reference to Description And Operation PCM connector view included from each Pinpoint Tests. This link/reference was included because of multiple PCM connector designs.
^ Reference Values has included PCM connector views for each application.