LEMON Manuals: Even more car manuals for everyone
Home >> Ford >> 2000 >> Taurus LX, 3.0 2, AX4S >> Repair and Diagnosis >> External Pages >> Different car >> Section 1837 (Engine Controls Self-Diagnostics - EEC-V - CNG & Gasoline - System Tests A - FD) >> Test DA: Temperature Sensor Test (IAT, ECT & EOT) >> Diagnostic Aids

Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 30 other vehicles, including the 2001 Mercury Sable, 2001 Mercury Mountaineer, 2001 Mercury Grand Marquis, 2001 Mercury Cougar, and 2001 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: After each service or repair procedure has been completed, reconnect all components. Clear DTCs and repeat QUICK TEST procedures to ensure all EEC-V systems are working properly and DTCs are no longer present.

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 and engine oil temperature must be more than 50°F (10°C) to pass KOEO SELF-TEST. Engine coolant temperature must be more than 180°F (82°C) and engine oil temperature must be more than 150°F (66°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:

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

NOTE: On some models, IAT sensor is part of Mass Airflow (MAF) sensor assembly. If all 6 terminals of MAF sensor connector are being used, IAT sensor is integral to MAF sensor. See WIRING DIAGRAMS article.
NOTE: Proceed to DTC testing steps listed in FAULT CODE SETTING CONDITION  table of fault code setting condition.
FAULT CODE SETTING CONDITION

Fault Code(1) KOEO KOER Continuous Memory
P0112  DA20  DA20  DA90
P0113  DA10  DA10  DA90
P0116 (ECT Sensor) 1       DA80
P0117 (ECT Sensor) 1   DA20  DA20  DA90
P0118 (ECT Sensor) 1   DA10  DA10  DA90
P0125      DA100
P1112      DA90
P1116 (ECT Sensor) 1   DA1  DA1  
P1117 (ECT Sensor) 1       DA90
P1183      DA111
P1184      DA110
(1) For Engines equipped with Cylinder Head Temperature Sensor (CHT) see FAULT CODE SETTING CONDITION 

  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 Or Connector
    • Faulty Sensor
    • Faulty PCM

    If directed here because engine is a no-start, go to step  3). If vehicle has a stalling problem, go to appropriate symptom under SYMPTOMS in TROUBLE SHOOTING - NO CODES - EEC-V - CNG & GASOLINE article. Start and run engine at 2000 RPM until engine reaches normal operating temperature. 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 when KOER ON-DEMAND SELF-TEST was originally performed. Repair any other DTCs that are present.

  2. 2) Check VREF Circuit Voltage To TP Sensor

    Turn ignition switch to OFF position. Disconnect Throttle Position (TP) sensor. Turn ignition switch to ON position. Using a DVOM, 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, step  1).

  3. 3) Check ECT Sensor Resistance With Engine Off

    Turn ignition switch to OFF position. Disconnect ECT sensor. Using a DVOM, measure resistance between ECT sensor SIG and SIG RTN circuit terminals. See IAT, ECT & EOT SENSOR SPECIFICATIONS  table. See Fig 1. If resistance is not as specified, replace faulty ECT sensor. If resistance is as specified, perform following step as applicable:
    • For diagnosing vehicles with an ECT sensor related fault, or engine is a no-start, DO NOT service DTC P1116 at this time. See NO START/NORMAL CRANK symptom under SYMPTOMS in TROUBLE SHOOTING - NO CODES - EEC-V - CNG & GASOLINE article.
    • For diagnosing vehicles with cooling fan problems or engine cooling problems, DO NOT service DTC P1116 at this time. Service next DTC. If no other DTCs are present, repair by symptom. See SYMPTOMS in TROUBLE SHOOTING - NO CODES - EEC-V - CNG & GASOLINE article.
    • For vehicles with no other fault conditions or DTCs, go to next step.
    Fig 1: Identifying Engine Coolant Temperature (ECT) Sensor Circuits & Connector Terminals
    G00013242Courtesy of FORD MOTOR CO.
    Fig 2: Identifying Engine Oil Temperature (EOT) Sensor Circuits & Connector Terminals (LS)
    G00013243Courtesy of FORD MOTOR CO.
    Fig 3: Identifying Intake Air Temperature (IAT) Sensor Circuits & Connector Terminals (Continental, Cougar 2.5L, Crown Victoria, Expedition, F150 Pickup, Grand Marquis, LS, Mustang 4.6L & Ranger 2.5L)
    G00013244Courtesy of FORD MOTOR CO.
    Fig 4: Identifying MAF With Integrated Intake Air Temperature (IAT) Sensor Circuits & Connector Terminals (Cougar 2.0L & Focus)
    G00013245Courtesy of FORD MOTOR CO.
    Fig 5: Identifying MAF With Integrated Intake Air Temperature (IAT) Sensor Circuits & Connector Terminals (All Other Models)
    G00013246Courtesy of FORD MOTOR CO.
    4. NOTE: Engine must be at normal operating temperature before taking temperature sensor measurements.
    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.

  4. 4) Check ECT Sensor Resistance With Engine Running
    Reconnect all connectors. Start engine and operate at 2000 RPM for 2 minutes. Turn ignition switch to OFF position. Disconnect ECT sensor. Using a DVOM, measure resistance between ECT sensor SIG and SIG RTN circuit terminals. See IAT, ECT & EOT SENSOR SPECIFICATIONS  table. See Fig 1. If resistance is not as specified, replace faulty ECT sensor. If resistance is as specified, replace PCM.
    IAT, ECT & EOT SENSOR SPECIFICATIONS (1)

    Temperature °F (°C) Volts k/Ohms
    50 (10) 3.51 58.75
    68 (20) 3.07 37.30
    86 (30) 2.60 24.27
    104 (40) 2.13 16.15
    122 (50) 1.70 10.97
    140 (60) 1.33 7.70
    158 (70) 1.02 5.37
    176 (80) 0.78 3.84
    194 (90) 0.60 2.80
    212 (100) 0.46 2.07
    230 (110) 0.35 1.55
    248 (120) 0.27 1.18
    (1) Values may vary by 15 percent.

  5. 10) DTC P0118 Or P0113: Check Voltage Between VREF & SIG RTN

    DTC P0118 (ECT) or P0113 (IAT) indicates ECT or IAT sensor signal is more than self-test maximum. Maximum measurement should be 4.6 volts at -58°F (-50°C). Check for following possible causes:
    • Open Circuit In Harness Or Connector
    • Sensor Signal Short To Power
    • Faulty Sensor
    • Faulty PCM

    Turn ignition switch to OFF position. Disconnect TP sensor connector. Turn ignition switch to ON position. Using a DVOM, 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, step  1).

  6. 11) Simulate Opposite Signal To PCM

    Turn ignition switch to OFF position. Disconnect suspect temperature sensor. Connect a jumper wire between ECT or IAT sensor SIG and SIG RTN terminal at suspect sensor harness connector. With scan tool installed, turn ignition switch to ON position.
    NOTE: If a scan tool communication error is displayed, remove jumper wire and go to step  13).

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

  7. 12) Check Temperature Sensor SIG & 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. Using a DVOM, measure resistance of SIG RTN circuit between PCM harness connector SIG RTN terminal and suspect sensor harness connector SIG RTN terminal. See Fig 1-Fig 5 . See WIRING DIAGRAMS article.

    Using a DVOM, measure resistance of SIG circuit between PCM harness connector ECT or IAT terminal and suspect sensor harness connector ECT or IAT terminal. If both resistance measurements are less than 5 ohms, replace PCM. If either resistance measurement is 5 ohms or more, repair open in affected circuit.

  8. 13) Check Temperature Sensor SIG Circuit For Short To VREF

    Turn ignition switch to OFF position. Disconnect PCM connector(s). Turn ignition switch to ON position. Using a DVOM, measure resistance between PCM harness connector VREF circuit terminal and SIG circuit (ECT or IAT) at suspect sensor harness connector. See Fig 1-Fig 5 . See WIRING DIAGRAMS article. If resistance is more than 10 k/ohms, replace PCM. 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) KOEO & KOER 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. Connect scan tool to Data Link Connector (DLC). Turn ignition switch to ON position. Using scan tool, select ECT-V or IAT-V PID from PID/DATA MONITOR & RECORD menu. If PID value is 4.2 volts or less, go to next step. If PID value is more than 4.2 volts, replace faulty temperature sensor.

  10. 21) Check VREF Circuit Voltage To TP Sensor

    Turn ignition switch to OFF position. Disconnect TP sensor connector. Turn ignition switch to ON position. Using a DVOM, measure voltage between TP sensor harness connector VREF and SIG RTN terminals. If voltage is 4-6 volts, connect TP sensor and go to next step. If voltage is not 4-6 volts, see TEST C, step  1).

  11. 22) Check Temperature Sensor SIG Circuit For Short To Ground

    Turn ignition switch to OFF position. Ensure suspect sensor is disconnected. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Using a DVOM, measure resistance between PCM harness connector ECT or IAT sensor SIG circuit terminal and PCM PWR GND and SIG RTN terminals. See PCM PWR GND, SIG RTN & VREF TERMINAL IDENTIFICATION  table. If any resistance measurement is 10 k/ohms or less, repair short to ground. If all resistance measurements are more than 10 k/ohms, replace PCM.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 22) to step 80). No test procedures have been omitted.
    12. NOTE: Ensure engine temperature is at ambient room temperature before performing this test step.

  12. 80) Continuous Memory DTC P0116: Check ECT Sensor Resistance With Engine Off
    DTC P0116 indicates ECT sensor drifted higher than normal sensor calibration curve and could prevent one or more OBD-II monitors from functioning. PCM will set DTC P0116 when all of the following conditions are met:
    • Engine coolant temperature at engine start up exceeds IAT temperature by more than calibrated value, about 30°F (1°C).
    • Engine coolant temperature exceeds a calibrated value, about 225°F (107°C).
    • Fuel, HEGO, catalyst and misfire monitors have not completed.
    • Calibrated timer to set DTC P0116 has expired.

    Possible causes for this fault are:

    • Faulty ECT Sensor
    • Coolant System Fault

    Turn ignition switch to OFF position. Disconnect ECT sensor. Using a DVOM, measure resistance between ECT sensor SIG and SIG RTN circuit terminals. See IAT, ECT & EOT SENSOR SPECIFICATIONS  table. See Fig 1. If resistance is not as specified, replace faulty ECT sensor. If resistance is as specified, go to next step.

    13. NOTE: Engine must be at normal operating temperature before taking temperature sensor measurements.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 81) to step 90). No test procedures have been omitted.

  13. 81) DTC P0116: Check ECT Sensor Resistance With Engine Running
    Reconnect ECT connector. Start engine and operate at 2000 RPM for 2 minutes. Turn ignition switch to OFF position. Disconnect ECT sensor. Using a DVOM, measure resistance between ECT sensor SIG and SIG RTN circuit terminals. See IAT, ECT & EOT SENSOR SPECIFICATIONS  table. See Fig 1. If resistance is not as specified, replace faulty ECT sensor. If resistance is as specified, fault is not present at this time. Perform DRIVE CYCLE PROCEDURES under ADDITIONAL SYSTEM FUNCTIONS to determine if fuel, HEGO, catalyst and misfire monitors can be executed. Repeat QUICK TEST .

  14. 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

    Connect scan tool to Data Link Connector (DLC). Turn ignition switch to ON position. Using scan tool, select ECT-V and IAT-V PID from PID/DATA MONITOR & RECORD menu. While observing appropriate PID, tap on sensor and wiggle sensor connector to simulate road shock. If no change in PID voltage reading occurs, go to next step. If any change in PID voltage reading occurs, turn ignition switch to OFF position. Inspect connectors for loose, damaged or corroded terminals. Repair as necessary. If connectors are okay, replace faulty temperature sensor. If directed here for Continuous Memory DTCs P1112 and P1117, perform DRIVE CYCLE PROCEDURES under ADDITIONAL SYSTEM FUNCTIONS to verify repair. Repeat QUICK TEST .

  15. 91) Check EEC-V Wiring Harness

    While still observing PID, wiggle and bend small sections of wiring harness working toward PCM. If no changes in PID voltage reading occurs, go to next step. If changes in PID voltage reading occurs, isolate fault and repair as necessary. If directed here for Continuous Memory DTCs P1112 and P1117, perform DRIVE CYCLE PROCEDURES under ADDITIONAL SYSTEM FUNCTIONS to verify repair. Repeat QUICK TEST .

  16. 92) Inspect PCM & Wiring Harness Connectors

    Turn ignition switch to OFF position. Disconnect PCM connector(s). Inspect connector(s) for damaged terminals, corrosion and loose terminals. If connectors and terminals are damaged, repair as necessary. If directed here for Continuous Memory DTCs P1112 and P1117, perform DRIVE CYCLE PROCEDURES under ADDITIONAL SYSTEM FUNCTIONS to verify repair. Repeat QUICK TEST . If connectors and terminals are okay, fault cannot be identified at this time. Testing is complete. If directed here for Continuous Memory DTCs P1112 and P1117, perform DRIVE CYCLE PROCEDURES under ADDITIONAL SYSTEM FUNCTIONS to verify repair. Repeat QUICK TEST .
    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.

  17. 100) Continuous Memory DTC P0125: Check Engine Coolant Level

    This DTC indicates ECT sensor has not reached the required temperature level to enter closed loop operating conditions within a specified amount of time after starting engine. Possible causes for this fault are:
    • Insufficient Engine Warm-Up Time
    • Thermostat Leaking Or Stuck Open
    • Malfunctioning CHT Or ECT Sensor
    • Low Coolant Level

    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.

  18. 110) DTC P1184: Check Operation Of EOT Sensor

    This DTC indicates Engine Oil Temperature (EOT) sensor signal was out of self-test range. Correct range for measurement is .3-1.2 volt. Possible causes for this fault are:
    • Faulty Sensor Or Connector
    • Fault In Harness
    • Faulty PCM

    Connect scan tool. Start and operate engine at 2000 RPM until engine temperature becomes stabilized. Perform KOER ON-DEMAND SELF-TEST . If DTC P1184 is present, turn ignition switch to OFF position and go to next step. If DTC P1184 is not present, engine oil temperature was not at operating temperature. Repair other DTCs as required.

  19. 111) DTC P0298, P1183 Or P1184: Check Temperature Signal

    These DTC indicate engine oil temperature protection strategy in PCM has been activated by engine oil over-temperature condition. Possible causes for this fault are:
    • Very High Engine RPM For An Extended Period Of Time
    • Overheating Condition
    • Fault In EOT Sensor Or Harness
    • Base Engine Problems

    Turn ignition switch to ON position (engine off). Using scan tool, select EOT-V PID from PID/DATA MONITOR & RECORD menu. If EOT-V PID voltage is less than .3 volt, go to next step. If EOT-V PID voltage is .3 volt or more go to step  115).

  20. 112) Simulate Opposite EOT Signal To PCM

    While monitoring EOT-V PID voltage, disconnect EOT sensor. If EOT-V PID voltage is more than 4.2 volts, replace EOT sensor. If EOT-V PID voltage is 4.2 volts or less, go to next step.

  21. 113) Check EOT SIG Circuit For Short To Ground

    Turn ignition switch to OFF position. Disconnect PCM connector(s). Using a DVOM, measure resistance PCM harness connector terminals No. C39 (EOT) and No. C17 (SIG RTN) circuits. See Fig 2. Using a DVOM, measure resistance between PCM harness connector terminals No. C39 (EOT) and No. A24, A25, A26, A27 and A43 (PWR GND) circuits. See Fig 6. If all resistance measurements are more than 10 k/ohms, replace PCM. If any resistance measurement is 10 k/ohms or less, repair short to ground in affected circuit.
    Fig 6: Identifying Powertrain Control Module Connector Terminals (LS)
    G00011081Courtesy of FORD MOTOR CO.
    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.

  22. 115) Check For High EOT Signal

    If EOT-V PID voltage is more than 4.2 volts, go to next step. If EOT-V PID voltage is 4.2 volts or less, go to step  120).

  23. 116) Simulate 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 EOT-V PID from PID/DATA MONITOR & RECORD menu. If EOT-V PID voltage is less than .3 volt, replace EOT sensor. If EOT-V PID voltage is .3 volt or more, go to next step.

  24. 117) Check EOT Sensor SIG & SIG RTN Circuits For Open

    Turn ignition switch to OFF position. Disconnect PCM connector(s). Using a DVOM, measure resistance of EOT (SIG) circuit between PCM harness connector terminal No. C39 and EOT sensor. See Fig 2. Using a DVOM, measure resistance of SIG RTN circuit between PCM harness connector terminal No. C17 and EOT sensor. If each resistance measurement is less than 5 ohms, replace PCM. If either resistance measurement is 5 ohms or more, repair open in affected 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.

  25. 120) Intermittent EOT Sensor Check

    While observing EOT-V PID, tap on EOT sensor and wiggle sensor connector to simulate road shock. If no large change in EOT-V PID voltage reading occurs, go to next step. If any large change in EOT-V PID voltage reading 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.

  26. 121) Check EEC-V Wiring Harness

    While still observing EOT-V PID, wiggle and bend small sections of wiring harness working toward PCM. If no large change in EOT-V PID voltage reading occurs, fault is not present at this time. Perform DRIVE CYCLE PROCEDURES under ADDITIONAL SYSTEM FUNCTIONS to verify repair. Repeat QUICK TEST . If any large change in EOT-V PID voltage reading occurs, isolate fault and repair as necessary. Clear DTCs and perform DRIVE CYCLE PROCEDURES under ADDITIONAL SYSTEM FUNCTIONS to verify repair. Repeat QUICK TEST .
    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.

  27. 130) DTC P0298: Engine Oil Over-Temperature Condition

    Engine oil temperature protection strategy in PCM has been activated. Check for engine overheating condition or mechanical problem. If problem is found, repair as necessary. If problem is not found, go to next step.

  28. 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 activated engine protection strategy in PCM.
scientia non olet · About LEMON Manuals