Engine Controls - Tests W/o Codes - Gasoline: Diagnosis Ford Aerostar I

DRIVEABILITY SYMPTOM CHECK PROCEDURES

Symptom checks cannot be used properly unless the problem or driveability characteristic actually happens while the vehicle is being tested. To reduce diagnostic time, ensure steps in the BASIC TESTING and TESTS W/CODES articles have been performed before attempting to diagnose a symptom.

DIAGNOSTIC ROUTINES are indexed for your convenience. For the menu screen, The titles have been shortened to ROUTINE. This allows for more of the information to be displayed on the menu. They should be used to identify systems and components that should be checked to identify a fault. Perform the check or adjustment as indicated in the appropriate ROUTINE chart. a reference may be given to direct you to another test procedure or to a specific CIRCUIT TEST in the TESTS W/CODES article. This will provide additional information for checking a component or circuit.

On vehicles equipped with EEC-IV systems, charts are provided to direct the technician to CIRCUIT TESTS in the TESTS W/CODES article. This is the circuit or component most likely to be the cause of the applicable driveability symptom. These charts should only be used in conjunction with the DIAGNOSTIC ROUTINES.

SYMPTOM-TO-ROUTINE MENU

SYMPTOM-TO-DIAGNOSTIC ROUTINE MENU

INTERMITTENT PROBLEM DIAGNOSIS

Use intermittent test procedures to locate intermittent driveability problems that do not occur when the vehicle is being tested. These problems may cause a noticeable driveability problem or cause the CHECK ENGINE or SERVICE ENGINE SOON warning light to illuminate on some vehicles.

Intermittent fault testing requires the duplication of circuit or component failure in order to identify the fault. These procedures may lead to the computer recording a fault code (on some systems) which may help in diagnosis.

If problem vehicle does not produce fault codes, it will be necessary to monitor voltage or resistance values using a Digital Volt Ohmmeter (DVOM) while attempting to reproduce conditions that will create an intermittent fault. A change in status on the DVOM will indicate a fault has been located.

When using a DVOM or Scan tool to pinpoint faults, monitor voltage reading with ignition on or vehicle running. A change in status on the voltmeter while performing intermittent test procedures will indicate area of fault.

When using an ohmmeter to detect problems in the circuit, monitor circuit resistance (ohms) with ignition off or with battery disconnected. A change in ohmmeter reading while performing test procedures will indicate area of fault.

CONTINUOUS MONITOR MODE (WIGGLE TEST)

This test allows a technician to attempt to re-create an intermittent fault while monitoring the system. This mode, also called the "wiggle test", may be used in both Key On Engine Off (KOEO) and Key On Engine Running (KOER) Self-Test modes. The CIRCUIT TESTS in TESTS W/CODES article specify the use of this procedure to identify intermittent faults in specific circuits or components.

KOEO WIGGLE TEST PROCEDURE

Connect test equipment. Turn ignition on and activate self-test with jumper lead or diagnostic tester. Wait 10 seconds, deactivate and then reactivate self-test. Wiggle test mode has been achieved. Tap, move and wiggle the suspected sensor and/or harness area. If a fault is detected, a code may be stored in memory and indicated at the diagnostic tester or Scan tool. Record code and perform CIRCUIT TEST indicated in CONTINUOUS MEMORY CODES chart. See TESTS W/CODES article.

KOER WIGGLE TEST PROCEDURE

Connect test equipment. Turn ignition off and wait 10 seconds. Start engine. Activate self-test with jumper lead or diagnostic tester. Wait 10 seconds, deactivate and then reactivate self-test. DO NOT turn engine off. Engine running Wiggle Test mode has been achieved. Tap, move and wiggle the suspected sensor and/or harness area. If a fault is detected, a code may be stored in memory and indicated at the diagnostic tester or Scan tool. Record or retrieve code and perform CIRCUIT TEST indicated in Continuous Memory Codes chart. See TESTS W/CODES article.

ROUTINE 222 - STATE EMISSION TEST FAILURE

Note. Canada and some states or metropolitan areas in the United states require periodic Idle Emission Tests. All Ford products have been designed to pass these tests. If a Ford product fails an Idle Emission Test, it is probable that The engine temperature was not warm and stabilized prior to the test. 2) The vehicle had Idle excessively long prior to the test.

Prior to starting any repairs, complaints of Idle Emission Test failure should be verified. The following example encompasses most of the emissions measurements modes of the current state Idle test procedures

1. Ensure that the engine is at normal operating temperature and that all accessories are turned off.
2. Read emissions at Idle.
3. Run engine at 2500+- 300 RPM.
4. Read emissions within 30 seconds.
5. Return engine Speed to Idle.
6. Read emissions within 30 seconds.

If any emission Components are replaced, Keep Alive Memory (KAM) should be cleared before repeating State Emission Test procedure. Refer to Quick Test Appendix.

ROUTINE 222 - STATE EMISSION TEST FAILURE

USING THE SYMPTOM-TO-DIAGNOSTIC FLOW CHART MENU

To use the SYMPTOM-TO-DIAGNOSTIC FLOW CHART MENU, find the appropriate engine size and symptom exhibited by the vehicle. Following the line to the right will give you the flow chart. The step will be designated in parenthesis ().

SYSTEM-TO-DIAGNOSTIC FLOW CHART MENU. Scheme 134