Diagnostic Aids

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Perform this test only when directed by QUICK TEST. This test is intended to diagnose the following:

Wiring harness circuits (CHT and SIG RTN).
Faulty CHT sensor.
Faulty Powertrain Control Module (PCM).

1) DTC P1116 Or P1288

DTC P1116 or P1228 indicates CHT sensor is out of self-test range. Possible causes for these faults are:
- Engine overheating.
- Low coolant level.
- Faulty sensor.
- Faulty sensor connector.
- Poor thermostat operation.
Start engine and raise speed to 2000 RPM until engine is at normal operating temperature. Perform KOER ON-DEMAND SELF-TEST . Check for DTC P1116 or P1288. If DTC P1116 or P1288 is not present, engine temperature was not stabilized. Service any other DTCs and repeat QUICK TEST . If DTC P1116 or P1288 is present, go to next step.

2) Check VREF Circuit Voltage

Turn ignition off. Disconnect TP sensor connector. Turn ignition on. Measure voltage between VREF and SIG RTN terminals at TP sensor wiring harness connector. See Fig 1 or Fig 2 . If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, reconnect sensor and go to TEST C .

Fig 1: Identifying TP Sensor Circuits & Connector Terminals (Contour 2.0L, Cougar 2.0L & Mystique 2.0L)
Courtesy of FORD MOTOR CO.

Fig 2: Identifying TP Sensor Circuits & Connector Terminals (Except Contour 2.0L, Cougar 2.0L & Mystique 2.0L)
Courtesy of FORD MOTOR CO.

3) Check CHT Sensor Circuit Resistance

Turn ignition off. Disconnect CHT sensor 2-pin connector. Measure resistance between CHT sensor terminals. See CHT SENSOR SPECIFICATIONS table. If resistance is as specified, go to next step. If resistance is not as specified, replace CHT sensor.

CHT SENSOR SPECIFICATIONS ⁽¹⁾

Temperature °F (°C)

Volts

Ohms

32 (0)

4.14

96,255

68 (20)

3.26

37,387

104 (40)

2.23

16,043

158 (70)

1.04

5268

185 (85) ⁽²⁾

.69 Or 3.86

3215

194 (90) ⁽²⁾

.60 Or 3.71

2750

212 (100) ⁽²⁾

.46 Or 3.41

2034

248 (120)

2.74

1155

284 (140)

2.10

689

302 (150)

1.81

542

320 (160)

1.55

430

338

1.33

345

356

1.13

279

374

.96

228

392

.82

188

410

.70

155

428

.60

130

446

.51

109

464

.44

482

.35

500

.33

⁽¹⁾	Value may vary by 15 percent.

⁽²⁾	At this temperature, there is a voltage overlap zone where it is possible to have either a cold end (low voltage) or hot end (high voltage) reading at the same temperature. Either voltage specification listed is correct.

4) Check CHT Sensor With Engine Running

Start engine. Ensure engine is at normal operating temperature. Raise engine speed to 2000 RPM for 2 minutes. Measure resistance between CHT sensor terminals. See CHT SENSOR SPECIFICATIONS table. If resistance is as specified, replace PCM. If resistance is not as specified, replace CHT sensor.

5) DTC P1289 Or P1290

These DTCs indicate CHT sensor circuit fault. Possible causes for these faults are:
- Open or grounded circuit.
- Faulty sensor.
- Faulty sensor connector.
- Faulty Powertrain Control Module (PCM).
Turn ignition on. Using scan tool, select CHT V PID from PID/DATA monitor menu. If PID voltage is less than .2 volt, go to next step. If PID voltage is .2 volt or more, go to step 7).

6) Check For Grounded Circuit

Disconnect CHT sensor 2-pin connector. Using scan tool, select CHT V PID from PID/DATA monitor menu. If PID voltage is more than 4.6 volts, replace CHT sensor. If PID voltage is 4.6 volts or less, go to step 21).

7) Check For Open Circuit

Connect a jumper wire between CHT sensor wiring harness connector terminals. Using scan tool, select CHT V PID from PID/DATA monitor menu.
NOTE: If communication link error is displayed, remove jumper wire and go to step 12).

If PID voltage is less than .2 volt, replace CHT sensor. If PID voltage is .2 volt or more, remove jumper wire and go to step 11).

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 7) to step 10). No test procedures have been omitted.

10) DTC P1118

This DTC indicates CHP sensor signal is more than self-test maximum. Possible causes for this fault are:
- Open circuit.
- Faulty CHT sensor.
- Faulty PCM.
Turn ignition off. Disconnect CHT sensor 2-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Connect a jumper wire between CHT sensor wiring harness connector terminals. Turn ignition on.

NOTE: If communication link error is displayed, remove jumper wire and go to step 12).

Using scan tool, select CHT V PID from PID/DATA monitor menu. If PID voltage is less than .2 volt, replace CHT sensor. If PID voltage is .2 volt or more, remove jumper wire and go to next step.

11) Check For Open Circuit

Turn ignition off. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Measure resistance of CHT circuit between CHT sensor wiring harness connector and PCM connector pin No. 66. Also measure resistance of SIG RTN circuit between CHT sensor wiring harness connector and PCM connector pin No. 91. If both resistance readings are less than 5 ohms, replace PCM. If any resistance reading is 5 ohms or more, repair open circuit.

12) Check CHT Signal For Short To VREF

Turn ignition off. Disconnect CHT sensor 2-pin connector. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Measure resistance between PCM connector pins No. 66 and 90. If resistance is more than 10,000 ohms, replace PCM. If resistance is 10,000 ohms or less, repair circuit short to VREF.
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 20). No test procedures have been omitted.

20) DTC P0117

This DTC indicates CHT sensor signal is less than self-test minimum. Possible causes for this fault are:
- Open or grounded circuit.
- Faulty CHT sensor.
- Faulty PCM.
Turn ignition off. Disconnect CHT sensor 2-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Turn ignition on. Using scan tool, select CHT V PID from PID/DATA monitor menu. If PID voltage is more than 4.6 volts, replace CHT sensor. If PID voltage is 4.6 volts or less, go to next step.

21) Check VREF Circuit Voltage

Disconnect TP sensor connector. Measure voltage between VREF and SIG RTN terminals at TP sensor wiring harness connector. If voltage is 4-6 volts, reconnect TP sensor and go to next step. If voltage is not 4-6 volts, reconnect sensor and go to TEST C .

22) Check Signal Circuit For Short To Ground

Turn ignition off. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Measure resistance between PCM connector pin No. 66 (CHT) and pins No. 51 (PWR GND) and 91 (SIG RTN). If all resistance readings are more than 10,000 ohms, replace PCM. If any resistance reading is 10,000 ohms or less, repair circuit short.
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 22) to step 30). No test procedures have been omitted.

30) DTC P1285

This DTC indicates that PCM has sensed an engine overheat condition from CHT sensor. Check cooling system for leaks and restrictions. Check for cause of overheat condition. Repair as necessary.
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 30) to step 40). No test procedures have been omitted.

40) Engine Temperature Warning Light Always On, Engine Is Not Overheating

If QUICK TEST was performed and no DTCs are present, go to next step. If QUICK TEST was not performed, perform QUICK TEST and service any DTCs that are present.

41) Engine Temperature Warning Light Always On (No DTCs)

This DTC indicates that PCM has sensed a engine warning light circuit fault. Possible causes for this fault are:
- Faulty instrument cluster.
- Faulty wiring harness.
- Faulty PCM.
Disconnect PCM 104-pin connector. Turn ignition on. If engine temperature warning light is off and temperature gauge is reading in the normal zone, replace PCM. If engine temperature warning light is still on, check instrument cluster and temperature warning light circuits. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT in appropriate lemon-25® manual for diagnosis and testing.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 41) to step 90). No test procedures have been omitted.

90) Continuous Memory DTC P0117, P0118, P1117, P1289 Or P1290

These DTCs indicate intermittent CHT sensor failure. Possible causes for these faults are:
- Open or grounded circuit.
- Faulty CHT sensor.
- Low coolant level.
- Faulty PCM.
Turn ignition on. Using scan tool, select CHT PID from PID/DATA monitor menu. While observing CHT PID, lightly tap on CHT sensor to simulate road shock. Wiggle sensor connector. A fault is indicated by a sudden change of CHT PID temperature. If no fault is indicated, go to next step. If fault is indicated, turn ignition off. Disconnect and inspect connectors. If connectors are okay, replace CHT sensor. Clear DTCs and perform COMPREHENSIVE COMPONENT MONITOR REPAIR VERIFICATION DRIVE CYCLE. See DRIVE CYCLES under ADDITIONAL SYSTEM FUNCTIONS. Repeat QUICK TEST .

91) Check Wiring Harness

Ensure CHT PID is still selected. Starting at CHT sensor connector and working toward PCM, wiggle and shake small sections of wiring harness. A fault is indicated by a sudden change of CHT PID temperature. If no fault is indicated, go to next step. If fault is indicated, isolate and repair as necessary. Clear DTCs and perform COMPREHENSIVE COMPONENT MONITOR REPAIR VERIFICATION DRIVE CYCLE. See DRIVE CYCLES under ADDITIONAL SYSTEM FUNCTIONS. Repeat QUICK TEST .

92) Check PCM Wiring Harness

Turn ignition off. Disconnect CHT sensor and PCM connectors. Inspect connectors for loose, damaged or corroded terminals. Repair as necessary. Clear DTCs and perform COMPREHENSIVE COMPONENT MONITOR REPAIR VERIFICATION DRIVE CYCLE. See DRIVE CYCLES under ADDITIONAL SYSTEM FUNCTIONS. Repeat QUICK TEST . If connectors are okay, problem cannot be located at this time. Clear DTCs and perform COMPREHENSIVE COMPONENT MONITOR REPAIR VERIFICATION DRIVE CYCLE. See DRIVE CYCLES under ADDITIONAL SYSTEM FUNCTIONS. 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.

100) DTC P1299 or P0217

This DTC indicates an engine overheat condition was detected by CHT sensor and fail-safe cooling strategy was activated by FMEM. Possible causes for this fault are:
- Cooling system fault.
- Low coolant level.
- Engine mechanical fault.
Locate cooling system fault and repair as necessary.