Diagnostic Aids

Perform this test when instructed during QUICK TEST or if directed by other test procedures. This system test is intended to diagnose and isolate intermittent concerns for the following:

• All Engine Control Sub-Systems
• Vehicles With Coil Pack Ignition Systems

The intermittent test table is used to determine which test to perform for the suspect circuit. See INTERMITTENT TEST  table. Corresponding Parameter Identification (PIDs) for each circuit are listed. Some circuits do not have an associated PID and can be measured with a Digital Volt-Ohmmeter (DVOM). If vehicle has coil pack ignition system with a no-start condition, perform ignition test. Go to step  50).

1. 1) Direction For Intermittent Diagnostic Path
   
   There are 2 main procedures used to isolate and repair an intermittent concern. One procedure uses the Rotunda Distributorless Ignition System (DIS) Tester (007-00075) and the other uses a scan tool and a Digital Volt-Ohmmeter (DVOM). The distributorless ignition system tester is used on vehicles with coil pack ignition systems. If vehicle has an ignition concern and is equipped with coil pack ignition (except Contour, Cougar, Focus and Mystique 2.0L), go to step  50). If vehicle is not as specified, go to next step.
2. 2) Perform PCM Reset Procedure
   
   If PCM reset produce has already been performed, go to next step. If PCM reset procedure has not been performed, perform PCM RESET PROCEDURE  under SELF-DIAGNOSTIC SYSTEM. Ensure freeze frame data has been recorded before resetting PCM. After performing PCM reset procedure, go to next step.
3. 3) Select PIDs Related To Symptom
   
   Scan tool and a list of PIDs must be used to indicate area of fault. Obtain symptom from customer description. Use REFERENCE VALUE SYMPTOM table and REFERENCE VALUE/PID MEASUREMENT SIGNAL table in appropriate PIN VOLTAGE/PID VALUE CHARTS article to identity PIDs that relate to symptom. Note and make a list of symptom related PIDs and go to next step.
4. 4) Symptom Verification
   
   Path to symptom verification is optional, but is recommended for the following reasons.
   • If Vehicle Is In For A Repeat Repair
   • No DTCS Present
   • Customer Has Difficulty Describing Symptom

   If symptom needs to be verified, go to next step. If symptom is known and does not need to be verified, go to step  11).

5. 5) Note All Available Data To Aid In Symptom Verification
   
   Collect as much data as possible to aid in determining intermittent fault area. Note any freeze frame data that was recorded in step  2) or during QUICK TEST . Note any Continuous Memory DTCs that were present prior to performing PCM RESET in step  2). Obtain any information from customer that would aid in determining fault area. Go to next step.
NOTE: A road test may be necessary to recreate conditions that originally caused DTC to set.
6. 6) Attempt To Recreate Symptom
   Using scan tool, select and monitor PIDs displayed in freeze frame data (if available) and PIDs on list that was developed in step  3). Using freeze frame data recorded earlier, recreate conditions described by each freeze frame PID. Pay particular attention to ECT LOAD, RPM and VSS PIDs. Use any information available from customer to aid in producing conditions for recreating symptom. When symptom occurs, press trigger on scan tool to begin recording. Refer to scan tool instruction manual for recorder function operation. If symptom is reproduced, go to step  11). If symptom cannot be reproduced, go to next step.
NOTE: PIDs for PCM outputs in PIN VOLTAGE/PID VALUE TABLES in appropriate PIN VOLTAGE/PID VALUE CHARTS article represent commanded values only. Circuit measurements made with DVOM indicate actual output status. If circuit measurement made with a DVOM differs from scan tool PID value, a circuit fault may be indicated. PCM input PIDs that differ from circuit measurements made with a DVOM indicate a possible PCM fault.
7. 7) Recreate Symptom Using Intermittent Road Test Procedure
   Intermittent road test procedure is the last attempt to locate area of problem before physically disturbing vehicle circuits. Intermittent road test procedure requires monitoring PID values or making circuit measurements with a DVOM under 4 conditions: Key On Engine Off (KOEO), HOT IDLE, and/or vehicle road test at 30 MPH, and/or 55 MPH. During road test at 30 MPH and/or 55 MPH, a ride along assistant is necessary. Use PID values and circuit values in PIN VOLTAGE/PID VALUE TABLES in appropriate PIN VOLTAGE/PID VALUE CHARTS article to compare with actual PID values and circuit measurements made during road test. Perform KOEO condition listed in PIN VOLTAGE/PID VALUE TABLES in appropriate PIN VOLTAGE/PID VALUE CHARTS article. Turn ignition switch to ON position. Using scan tool, select and monitor values. Using a DVOM, measure circuits at PCM terminal identified in PIN VOLTAGE/PID VALUE TABLES in appropriate PIN VOLTAGE/PID VALUE CHARTS article. Compare scan tool PID values with circuit values made with DVOM. If any PID values are out of range, go to step  11). If all PID values are within range, go to next step.
8. 8) Recreate Symptom Using Hot Idle Road Test Procedure
   
   Start engine and allow to idle. Ensure engine is at normal operating temperature of at least 195°F (87°C). Continue to monitor same PIDs and circuits as in step  7). If any values are out of range, go to step  11). If all values are in range, go to next step.
9. 9) Recreate Symptom Using 30 MPH Road Test
   
   Road test vehicle at 30 MPH and continue to monitor same PIDs and circuits as in step  7). If any values are out of range, go to step  11). If all values are in range, go to next step.
10. 10) Recreate Symptom Using 55 MPH Road Test
    
    Road test vehicle at 55 MPH and continue to monitor same PIDs and circuits as in step  7). If any values are out of range, go to next step. If all values are in range, it is now necessary to physically disturb selected circuit in an attempt to recreate intermittent concern. Go to next step.
11. 11) Select Circuits To Be Tested From Intermittent Test Table
    
    Remain in scan tool PID selection menu. If steps  7)- 10) (intermittent road tests) were performed, select PIDs or circuits that values did not match PID values or circuit values made using DVOM and terminal voltage/PID value chart. If steps  7)- 10) were not performed, select PIDs from PID list made in step  3). On all applications, go to INTERMITTENT TEST  table. Match selected PIDs to corresponding circuit in INTERMITTENT TEST table. It is possible to have more than one circuit to test. If a PID recording was made with scan tool in step  6), it may be helpful to replay recording at this time. Using INTERMITTENT TEST table, determine test to perform (input or output). To perform input test, go to next step. To perform output test, go to step  16). If PID or circuit is not listed in INTERMITTENT TEST table, go to SYMPTOMS in TROUBLE SHOOTING - NO CODES - EEC-V (GASOLINE) article and diagnose driveability symptom.
12. 12) KOEO Intermittent Input Test Procedure For PCM Sensors
    
    Using circuits selected from INTERMITTENT TEST  table, select only recommended PIDs to monitor with scan tool. If a PID is not available for a circuit, use a DVOM to monitor circuit. Go to area of suspect wiring or component fault. Turn ignition switch to ON position. If input is a switch-type component, turn switch on manually. Observe PID or DVOM value while lightly tapping on component, and then wiggling sensor wiring harness from component to PCM. If a fault is indicated, PID value or DVOM reading will suddenly change. Compare to correct KOEO values listed in PIN VOLTAGE/PID VALUE TABLES in appropriate PIN VOLTAGE/PID VALUE CHARTS article. If no fault is indicated, go to next step. If a fault is indicated, isolate fault and repair as necessary. If wiring harness and connector(s) is okay, replace suspect component.
CAUTION: Ensure hands, clothing or tools are clear of cooling fans, engine drive belts and/or hot surfaces while performing test steps with engine running.
13. 13) KOER Intermittent Input Test Procedure For PCM Sensors
    Start engine and allow to idle. Continue to monitor PIDs and/or circuits as in step  12). Go to area of suspect wiring or component fault. If input is a switch-type component, turn switch on manually. Observe PID or DVOM value while lightly tapping on component, and then wiggling sensor wiring harness from component to PCM. If a fault is indicated, value will suddenly change. Compare to correct HOT IDLE values listed in appropriate PIN VOLTAGE/PID VALUE CHARTS article. If no fault is indicated, turn ignition switch to OFF position and go to next step. If a fault is indicated, isolate fault and repair as necessary. If wiring harness and connector(s) is okay, replace suspect component.
14. 14) KOEO Intermittent Water Soak Test Procedure For PCM Sensors
    
    Turn ignition switch to ON position. Continue to monitor PIDs and/or circuits as in step  13). Go to area of suspect wiring or component fault. If input is a switch-type component, turn switch on manually. While observing PID or DVOM value, lightly spray water on suspect component, circuit or connectors from component to PCM. Include any relays or relay modules associated with fault. If a fault is indicated, value will suddenly change. Compare to correct KOEO values in appropriate PIN VOLTAGE/PID VALUE CHARTS article. If no fault is indicated, go to next step. If a fault is indicated, isolate fault and repair as necessary. If wiring harness and connector(s) is okay, replace suspect component.
15. 15) KOER Intermittent Water Soak Test Procedure For PCM Sensor
    
    Start engine and allow to idle. Continue to monitor PIDs and/or circuits as in step  14). Go to area of suspect wiring or component fault. If input is a switch-type component, turn switch on manually. While observing PID value, lightly spray water on suspect component, circuit or connectors from component to PCM. Include any relays or relay modules associated with fault. If a fault is indicated value will suddenly change. Compare to correct HOT IDLE values in appropriate PIN VOLTAGE/PID VALUE CHARTS article. If no fault is indicated, go to next step. If a fault is indicated, isolate fault and repair as necessary. If wiring harness and connector(s) is okay, replace suspect component.
NOTE: PIDs selected from INTERMITTENT TEST  table will display commanded values only. Circuit measurements made with DVOM will indicate actual values.