Test DA: Engine Coolant & Intake Air Temperature Sensors: Testing
- 1) DTC P0110 Or P0115: Check Signal To PCM
DTC P0110 indicates an excessively high or low voltage is received from IAT sensor or a rationally incorrect voltage from IAT sensor is received by PCM compared with voltage signal from ECT sensor. DTC P0115 indicates an excessively high or low voltage from ECT sensor is sent to PCM. When this fault occurs, PCM will enter into fail safe mode. Possible causes are as follows:- Open in harness circuit (ECT or IAT).
- ECT or IAT circuit shorted to GND or VPWR.
- Faulty ECT or IAT sensor.
- Faulty PCM.
Turn ignition off. Connect scan tool to Data Link Connector (DLC). Turn ignition on. Using scan tool, access ECT or IAT PID from PID/DATA MONITOR & RECORD menu. If ECT or IAT PID reads between -4°F (-20°C) and 300°F (149°C), sensors are within acceptable range. Fault may be intermittent. Go to TEST Z , step 1), or go to INTERMITTENTS in TROUBLE SHOOTING - NO CODES - VILLAGER article. If ECT and IAT PIDs read more than 300°F (149°C), go to step 20). If IAT and ECT PIDs read less than -4°F (-20°C), go to step 10).
- 10) Simulate Low Level (High Temperature) Signal To PCM
Turn ignition off. Disconnect suspect temperature sensor. Ensure scan tool is connected to DLC. Turn ignition on. Connect a jumper wire between suspect sensor harness connector terminals. See Figure.NOTE: If scan tool has a communication problem, disconnect jumper wire immediately and go to step 12).Using scan tool, access ECT or IAT PID from PID/DATA MONITOR & RECORD menu. If ECT or IAT PIDs read more than 300°F (149°C), replace suspect sensor, restore wiring connections and repeat QUICK TEST . If ECT or IAT PIDs read 300°F (149°C) or less, remove jumper wire and go to next step.
- 11) Check Continuity Of Sensor Signal & SIG RTN Circuits
Turn ignition off. Disconnect PCM harness connector. Inspect connector for damage, pushed out pins, corrosion, etc. Using DVOM, measure resistance of signal and SIG RTN circuits between suspect sensor harness connector terminal and PCM harness connector terminals No. 59 (ECT) or No. 61 (IAT). See Figure. If signal and SIG RTN circuit resistances are less than 5 ohms, go to next step. If either resistance is 5 ohms or more, repair open in affected circuit. See WIRING DIAGRAMS article. - 12) Check Sensor Signal Circuit Shorted To VREF
Turn ignition off. Disconnect PCM harness connector, if not already done. Using DVOM, measure resistance between suspect sensor signal and VREF circuits at PCM harness connector terminals No. 59 (ECT) or No. 61 (IAT), and VREF terminal No. 57 (Brown wire). If all resistance readings are more than 10 k/ohms, replace PCM and repeat QUICK TEST . If any resistance reading is 10 k/ohms or less, locate and repair wire shorted to VREF. See WIRING DIAGRAMS article.NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 19). No test procedures have been omitted. - 19) DTC P1217: Engine Overheat Condition
DTC P1217 indicates an engine overheat condition. Possible causes are as follows:- Cooling fan concerns.
- Cooling fan circuits open or shorted.
- Low engine coolant level.
- Base engine concerns.
- Engine cooling system concerns.
- ECT sensor concern.
If an engine overheat condition was sensed by ECT sensor, check coolant level or check for internal or external coolant leaks. Check for blockage of radiator and proper cooling fan operation. Repair as necessary. If cooling system is okay, check ECT sensor operation. Go to next step.
- 20) Simulate High Level (Low Temperature) Signal To PCM
Turn ignition off. Disconnect suspect temperature sensor. Connect scan tool to DLC. Turn ignition on. Using scan tool, access ECT or IAT PID from PID/DATA MONITOR & RECORD menu. If ECT or IAT PID reads less than -4°F (-20°C), replace sensor. If ECT or IAT sensor PID reads -4°F (-20°C) or more, go to next step. - 21) Check VREF Circuit Voltage To TP Sensor
Turn ignition off. Disconnect TP sensor harness connector. Turn ignition on. Using DVOM, measure voltage between VREF and SIG RTN terminals at TP sensor connector. See Figure. If voltage is 4.5-5.5 volts, VREF voltage is sufficient. Reconnect TP sensor and go to next step. If voltage is less than 4.5 volts, go to TEST C , step 2). If voltage is more than 5.5 volts, repair short to voltage on affected circuit. See WIRING DIAGRAMS article. - 22) Check Signal Circuit Short To Ground
Turn ignition off. Ensure suspect temperature sensor is disconnected. Disconnect PCM harness connector. Inspect connector for damaged pins and repair if necessary. Using DVOM, measure resistance between ECT or IAT circuits, and GND and SIG RTN circuits at PCM harness connector. See PCM TERMINAL CIRCUIT IDENTIFICATION and ECT, IAT & SIG RTN CIRCUIT IDENTIFICATION tables. If all resistances are more than 10 k/ohms, replace PCM. If any resistance is 10 k/ohms or less, repair short between affected circuits.NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 22) to step 100). No test procedures have been omitted. - 100) DTC P0125: Excessive Time To Enter Closed Loop
DTC P0125 indicates ECT sensor signal is not practical even when some time has passed after starting engine, or engine coolant temperature is insufficient for closed loop fuel control. Possible causes are as follows:- High resistance in the ECT sensor circuit.
- Faulty ECT sensor.
- Cooling system thermostat.
- Low coolant level.
Ensure sufficient engine warm-up period is allowed. Check coolant level and correct as necessary. If coolant level is okay, check thermostat operation. Replace if necessary. Clear all DTCs and repeat QUICK TEST .