Diagnostic Aids

Perform this test only when directed by QUICK TEST. Ambient air temperature must be at least 50°F (10°C) to receive valid input from Intake Air Temperature (IAT) sensor. Engine coolant temperature must be more than 50°F (10°C) to pass KOEO SELF-TEST and more than 180°F (82°C) to pass KOER SELF-TEST. Voltage values in this test are based on a 5-volt VREF signal. Values may vary up to 15 percent due to sensor and VREF variations.

This system test is intended to diagnose the following components and circuits.

• Intake Air Temperature (IAT) Sensor
• Engine Coolant Temperature (ECT) Sensor
• Engine Oil Temperature (EOT) Sensor
• Wiring Harness Circuits (IAT, ECT, EOT & SIG RTN)
• Powertrain Control Module (PCM)

To prevent replacing good components, ensure the following non-EEC areas or components are not cause of problem:

• Coolant Level Low.
• Cooling System, Water Pump Or Fan
• Engine Operating Temperature
• Engine Oil Level Low
• Thermostat
• Air Cleaner Duct
• Ambient Temperature

1. 1) DTC P1116: Check Operation Of ECT Sensor
   
   This DTC indicates sensor is out of self-test range. Correct range for measurement is .3-3.7 volts. Check for following possible causes:
   • Low Coolant Level
   • Faulty Harness Connector
   • Faulty Sensor

   Start engine and run until engine is at normal operating temperature. If vehicle is a no-start, go to step  3). If vehicle starts and stalls, diagnose by symptom. See SYMPTOMS in TROUBLE SHOOTING - NO CODES - EEC-V (GASOLINE) article. Ensure upper radiator hose is hot and pressurized. Repeat KOER ON-DEMAND SELF-TEST . If DTC P1116 is present, go to next step. If DTC P1116 is not present, engine was not at closed loop operating conditions. Repair any other DTCs that are present.

2. 2) Check VREF Circuit Voltage At TP Sensor
   
   Turn ignition switch to OFF position. Disconnect Throttle Position (TP) sensor. Turn ignition switch to ON position. Measure voltage between VREF and SIG RTN terminals at TP sensor harness connector. See Figure-Figure . If voltage is 4-6 volts, reconnect TP sensor and go to next step. If voltage is not 4-6 volts, go to TEST C .
3. 3) Check Temperature Sensor Resistance (KOEO)
   
   Turn ignition switch to OFF position. Disconnect ECT sensor. Measure resistance between ECT signal circuit terminal and SIG RTN terminal at ECT sensor harness connector. See IAT & ECT SENSOR SPECIFICATIONS  table. See Fig 1-Fig 5 . If resistance is not as specified, replace ECT sensor. If resistance is as specified, perform following step as applicable:
   • For diagnosing vehicles with ECT sensor related fault and a no-start condition, DO NOT service DTC P1116 at this time. Repair no-start condition. See TROUBLE SHOOTING - NO CODES - EEC-V (GASOLINE) article.
   • For diagnosing vehicles with cooling fan concerns or engine cooling concerns, DO NOT service DTC P1116 at this time. Service next DTC. If no other DTCs are present, identify symptom and repair as necessary. See TROUBLE SHOOTING - NO CODES - EEC-V (GASOLINE) article.
   • For diagnosing vehicles without a no-start condition, cooling fan concern or engine cooling concern, go to next step.
   Fig 1: Identifying Engine Coolant Temperature (ECT) Sensor Circuits & Connector Terminals

   Courtesy of FORD MOTOR CO.
   Fig 2: Identifying Engine Oil Temperature (EOT) Sensor Circuits & Connector Terminals (LS)

   Courtesy of FORD MOTOR CO.
   Fig 3: Identifying Intake Air Temperature (IAT) Sensor Circuits & Connector Terminals

   Courtesy of FORD MOTOR CO.
   Fig 4: Identifying MAF With Integrated Intake Air Temperature (IAT) Sensor Circuits & Connector Terminals (Contour 2.0L, Cougar 2.0L, Focus & Mystique 2.0L)

   Courtesy of FORD MOTOR CO.
   Fig 5: Identifying MAF With Integrated Intake Air Temperature (IAT) Sensor Circuits & Connector Terminals (Econoline, Escort 4V, Excursion, Explorer, F250/350/450 5.4L & 6.8L, Mountaineer, Sable, Taurus & Windstar)

   Courtesy of FORD MOTOR CO.
4. 4) Check Temperature Sensor Resistance (KOER)
   
   Reconnect all connectors. Start engine and operate at 2000 RPM for 2 minutes. Turn ignition switch to OFF position. Disconnect ECT sensor. Measure resistance between ECT signal circuit terminal and SIG RTN terminal at ECT sensor harness connector. See IAT & ECT SENSOR SPECIFICATIONS  table. If resistance is as specified, replace PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Program PCM. See FLASH VEHICLE IDENTIFICATION BLOCK PROCEDURE . If resistance is not as specified, replace ECT sensor.
   IAT & ECT SENSOR SPECIFICATIONS ⁽¹⁾
   
   

   Temperature °F (°C)	Volts	Ohms
   50 (10)	3.51	58,750
   68 (20)	3.07	27,300
   86 (30)	2.60	24,270
   104 (40)	2.13	16,150
   122 (50)	1.70	10,970
   140 (60)	1.33	7700
   158 (70)	1.02	5370
   176 (80)	0.78	3840
   194 (90)	0.60	2800
   212 (100)	0.46	2070
   230 (110)	0.35	1550
   248 (120)	0.27	1180
   (1) Values may vary by 15 percent.

   NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 4) to step 10). No test procedures have been omitted.
5. 10) DTC P0118 Or P0113: Check Voltage Between VREF & SIG RTN
   
   Turn ignition switch to OFF position. Disconnect TP sensor connector. Turn ignition switch to ON position. measure voltage between VREF and SIG RTN circuits at TP harness connector. See Figure-Figure . If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, go to TEST C .
6. 11) Simulate Opposite Signal To PCM
   
   Turn ignition switch to OFF position. Disconnect suspect temperature sensor. Connect a jumper wire between signal circuit (ECT or IAT) terminal and SIG RTN terminal at suspect sensor harness connector. With scan tool installed, turn ignition switch to ON position.
   NOTE: If communication link error is displayed, remove jumper wire and go to step  13).

   Using scan tool, select ECT V or IAT V PID from PID/DATA MONITOR & RECORD menu. If IAT PID value is less than .2 volt, or ECT V PID is greater than 248°F (120°C), replace suspect sensor. If IAT PID value is .2 volt or more, or ECT V PID is 248°F (120°C) or less, remove jumper wire and go to next step.

7. 12) Check Sensor Signal & SIG RTN Circuits For Open
   
   Turn ignition switch to OFF position. Ensure suspect temperature sensor is disconnected. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Measure resistance between PCM connector terminal No. 38 (ECT sensor) or No. 39 (IAT sensor) and SIG RTN terminal at suspect sensor harness connector. Measure resistance between PCM connector terminal No. 91 (SIG RTN) and SIG RTN terminal at suspect sensor harness connector. If both resistance readings are less than 5 ohms, replace PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Program PCM. See FLASH VEHICLE IDENTIFICATION BLOCK PROCEDURE . If any resistance reading is 5 ohms or more, repair open circuit.
8. 13) Check For Sensor Signal Short To VREF
   
   Turn ignition switch to ON position. Measure resistance between ground and signal circuit (ECT or IAT) at suspect sensor harness connector. If resistance is more than 10 k/ohms, replace PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Program PCM. See FLASH VEHICLE IDENTIFICATION BLOCK PROCEDURE . If resistance is 10 k/ohms or less, repair short to VREF in wiring harness.
   NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 13) to step 20). No test procedures have been omitted.
9. 20) DTC P0117 Or P0112: Simulate Opposite Signal To PCM
   
   DTC P0117 (ECT) or P0112 (IAT) indicates sensor signal is less than self-test minimum. Minimum signal for IAT and ECT sensor is .2 volt. Possible causes for these faults are:
   • Circuit Grounded In Wiring Harness
   • Faulty Sensor
   • Faulty Connection
   • Faulty PCM

   Turn ignition switch to OFF position. Disconnect suspect temperature sensor connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Turn ignition switch to ON position. Using scan tool, select ECT V of IAT V PID from PID/DATA MONITOR & RECORD menu. If PID value is less than 4.2 volts, go to next step. If PID value is 4.2 volts or more, replace sensor.

10. 21) Check VREF Circuit Voltage At TP Sensor
    
    Turn ignition switch to OFF position. Disconnect TP sensor connector. Turn ignition switch to ON position. Measure voltage between VREF and SIG RTN at TP sensor harness connector. If voltage is 4-6 volts, connect TP sensor and go to next step. If voltage is not 4-6 volts, see TEST C .
11. 22) Check Temperature Signal Circuit For Short To Ground
    
    Turn ignition switch to OFF position. Disconnect suspect sensor. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Measure resistance between PCM connector terminal No. 91 and terminal No. 38 (ECT) or No. 39 (IAT). If any resistance reading is less than 10 k/ohms, repair short to ground. If all resistance readings are 10 k/ohms or more, replace PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Program PCM. See FLASH VEHICLE IDENTIFICATION BLOCK PROCEDURE .
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 22) to step 90). No test procedures have been omitted.
12. 90) Continuous Memory DTC P0112, P1112, P0113, P0117, P1117 Or P0118: Check For Intermittent
    
    These DTCs indicate possible intermittent fault. Possible causes for these faults are:
    • Faulty Sensor
    • Faulty Sensor Connector
    • Open Or Grounded Circuit In Harness
    • Faulty PCM

    Turn ignition switch to ON position. Using scan tool, select ECT or IAT PID from PID/DATA MONITOR & RECORD menu. While observing PID, tap on sensor to simulate road shock. Wiggle sensor connector. If no change in ECT or IAT PID temperature reading occurs, go to next step. If any change in ECT or IAT PID temperature occurs, turn ignition switch to OFF position. Inspect connectors for loose, damaged or corroded terminals. Repair as necessary. If connectors are okay, replace sensor.

    If Continuous Memory DTCs P1112 and P1117 are present, reconnect all components. Clear DTCs and perform COMPREHENSIVE COMPONENT MONITOR REPAIR VERIFICATION DRIVE CYCLE. See DRIVE CYCLE PROCEDURES  under ADDITIONAL SYSTEM FUNCTIONS. After drive cycle is complete, repeat QUICK TEST  procedures to ensure all EEC-V systems are working properly and DTCs are no longer present.

13. 91) Check EEC-V Wiring Harness
    
    While still observing PID, wiggle and bend small sections of wiring harness working toward PCM. If no fault is found, go to next step. If fault is indicated, isolate fault and repair as necessary. If Continuous Memory DTCs P1112 and P1117 are present, reconnect all components. Clear DTCs and perform COMPREHENSIVE COMPONENT MONITOR REPAIR VERIFICATION DRIVE CYCLE. See DRIVE CYCLE PROCEDURES  under ADDITIONAL SYSTEM FUNCTIONS. After drive cycle is complete, repeat QUICK TEST  procedures to ensure all EEC-V systems are working properly and DTCs are no longer present.
14. 92) Inspect PCM & Wiring Harness Connectors
    
    Turn ignition switch to OFF position. Disconnect PCM connector(s). Inspect connector for damaged terminals, corrosion and loose terminals. If connectors and terminals are damaged, repair as necessary. If Continuous Memory DTCs P1112 and P1117 are present, reconnect all components. Clear DTCs and perform COMPREHENSIVE COMPONENT MONITOR REPAIR VERIFICATION DRIVE CYCLE. See DRIVE CYCLE PROCEDURES  under ADDITIONAL SYSTEM FUNCTIONS. After drive cycle is complete, repeat QUICK TEST  procedures to ensure all EEC-V systems are working properly and DTCs are no longer present. If connectors and terminals are okay, fault cannot be identified at this time. Testing is complete. If Continuous Memory DTCs P1112 and P1117 are present, reconnect all components. Clear DTCs and perform COMPREHENSIVE COMPONENT MONITOR REPAIR VERIFICATION DRIVE CYCLE. See DRIVE CYCLE PROCEDURES  under ADDITIONAL SYSTEM FUNCTIONS. After drive cycle is complete, repeat QUICK TEST  procedures to ensure all EEC-V systems are working properly and DTCs are no longer present.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 92) to step 100). No test procedures have been omitted.
15. 100) DTC P0125: Check Engine Coolant Level
    
    This DTC indicates ECT sensor has not reached normal operating temperature. Possible causes for this fault are:
    • Insufficient Engine Warm-Up Time
    • Thermostat Leaking Or Stuck Open
    • Low Coolant

    Check and repair cooling system as necessary. Clear DTCs and repeat QUICK TEST .

    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 100) to step 110). No test procedures have been omitted.
16. 110) DTC P1184: Check Operation Of Engine Oil Temperature (EOT) Sensor
    
    Connect scan tool. Run engine at 2000 RPM until engine oil temperature becomes stabilized. Check for KOER DTCs. If DTC P1184 is present, go to next step. If DTC P1184 is not present, engine oil temperature was not at operating temperature. Repair other DTCs as required.
17. 111) DTC P0298, P1183 Or P1184: Check Temperature Signal
    
    Using scan tool, select EOT V PID from PID/DATA MONITOR & RECORD menu. If voltage is less than .3 volt, go to next step. If voltage is .3 volt or more go to step  115).
18. 112) Induce Opposite EOT Signal To PCM
    
    While monitoring PID voltage, disconnect EOT sensor. If voltage is more than 4.2 volts, replace EOT sensor. If voltage is 4.2 volts or less, go to next step.
19. 113) Check EOT Signal Circuit For Short To Ground
    
    Turn ignition switch to OFF position. Disconnect PCM connector(s). Measure resistance PCM connector terminal C39 (EOT) and terminal C17 (SIG RTN) circuits and between terminal C39 (EOT) and terminals A24, A25, A26 and A27 (PWR GND) circuits. If each resistance measurement is more than 10 k/ohms, replace PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Program PCM. See FLASH VEHICLE IDENTIFICATION BLOCK PROCEDURE . If any resistance measurement is 10 k/ohms or less, repair short.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 113) to step 115). No test procedures have been omitted.
20. 115) Check For High EOT Signal
    
    If voltage is more than 4.2 volts, go to next step. If voltage is 4.2 volts or less, go to step  120).
21. 116) Induce Low Signal To PCM
    
    Disconnect EOT sensor. Connect jumper wire between EOT sensor harness connector terminals (EOT and SIG RTN). Turn ignition switch to ON position. Using scan tool, access EOTV PID from PID/DATA MONITOR & RECORD menu. If EOTV PID voltage is less than .3 volt, replace EOT sensor. If EOTV PID voltage is .3 volt or more, go to next step.
22. 117) Check EOT Sensor Signal & SIG RTN Circuits For Open
    
    Turn ignition switch to OFF position. Disconnect PCM connector(s). Measure resistance of EOT circuit between PCM harness connector terminal C39 and EOT sensor. Measure resistance of SIG RTN circuit between PCM harness connector terminal C17 and EOT sensor. If each resistance measurement is less than 5 ohms, replace PCM. If any resistance measurement is 5 ohms or more, repair open circuit.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 117) to step 120). No test procedures have been omitted.
23. 120) Intermittent EOT Sensor Check
    
    While observing PID, tap on sensor to simulate road shock. Wiggle sensor connector. If no large change in PID voltage occurs, go to next step. If any large change in PID voltage occurs, turn ignition switch to OFF position. Inspect connectors for loose, damaged or corroded terminals. Repair as necessary. If connectors are okay, replace EOT sensor.
24. 121) Check EEC-V Wiring Harness
    
    While still observing PID, wiggle and bend small sections of wiring harness working toward PCM. If no fault is found, go to next step. If fault is indicated, isolate fault and repair as necessary. If Continuous Memory DTCs P0298, P1183 or P1184 are present, reconnect all components. Clear DTCs and perform COMPREHENSIVE COMPONENT MONITOR REPAIR VERIFICATION DRIVE CYCLE. See DRIVE CYCLE PROCEDURES  under ADDITIONAL SYSTEM FUNCTIONS. After drive cycle is complete, repeat QUICK TEST  procedures to ensure all EEC-V systems are working properly and DTCs are no longer present.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 121) to step 130). No test procedures have been omitted.
25. 130) DTC P0298: Engine Oil Over Temperature
    
    Check for engine overheating condition or mechanical problem. If concern is found, repair as necessary. If concern is not found, go to next step.
26. 131) Check For EOT Sensor
    
    Engine oil temperature strategy can be activated in PCM without an EOT sensor. Ensure vehicle is equipped with an EOT sensor. If vehicle is equipped, go to step  111). If vehicle is not equipped, improper transmission gear selection or excessive RPM for extended period may have caused engine protection strategy in PCM.