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 here. This system test is intended to diagnose:
- Intake Air Temperature 2 (IAT2) Sensor
- IAT2 & SIG RTN Harness Circuits
- Powertrain Control Module (PCM)
NOTE:
Proceed to DTC testing steps listed in FAULT CODE SETTING CONDITION table of fault code setting condition.
FAULT CODE SETTING CONDITION
| Fault Code | KOEO | KOER | Continuous Memory |
|---|---|---|---|
| P0127 | DU30 | DU30 | DU30 |
| P1114 | DU20 | DU20 | DU20 |
| P1115 | DU10 | DU10 | DU10 |
- 10) DTC P1115: Simulate Opposite Signal To PCM
Disconnect IAT2 sensor connector. Connect a jumper wire between IAT2 sensor harness connector IAT2 and SIG RTN terminals. See Fig 1. Turn ignition switch to ON position. Using scan tool, select IAT2 PID from PID/DATA MONITOR & RECORD menu.If IAT2 PID voltage is less than .2 volt, replace IAT2 sensor. If IAT2 PID voltage is .2 volt or more, remove jumper wire and go to next step.
- 11) Check IAT2 Sensor Signal & SIG RTN Circuits For Open
Turn ignition switch to OFF position. Disconnect PCM connector. Using a DVOM, measure resistance of IAT2 signal circuit between PCM harness connector terminal and IAT2 sensor harness connector terminal. See Fig 1. Using a DVOM, measure resistance of IAT2 sensor SIG RTN circuit between PCM harness connector terminal and IAT2 sensor harness connector 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. - 12) Check IAT2 Sensor Signal Circuit For Short To VREF
Turn ignition switch to OFF position. Disconnect PCM connector. Using a DVOM, measure resistance between PCM harness connector VREF terminal and IAT2 sensor harness connector IAT2 signal terminal. See Fig 1 and Fig 2 . If resistance is more than 10 k/ohms, replace PCM. If resistance is 10 k/ohms or less, repair 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 P1114: Simulate Opposite Signal To PCM
Disconnect IAT2 sensor harness connector. Connect scan tool to Data Link Connector (DLC). Turn ignition switch to ON position. Using scan tool, select IAT2 PID from PID/DATA MONITOR & RECORD menu. If IAT2 PID voltage is more than 4.2 volts, replace IAT2 sensor. If IAT2 PID voltage is 4.2 volts or less, go to next step. - 21) Check VREF 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 VREF and SIG RTN terminals at TP sensor harness connector. See Fig 2. If voltage is 4-6 volts, VREF voltage is sufficient, reconnect TP sensor connector and go to next step. If voltage is not 4-6 volts, go to TEST C, step 1). - 22) Check IAT2 Sensor Signal Circuit For Short To Ground
Turn ignition switch to OFF position. Disconnect PCM connector. Using a DVOM, measure resistance between PCM harness connector IAT2 and SIG RTN terminals. See Fig 1. Using a DVOM, measure resistance between PCM harness connector IAT2 terminal and PWR GND terminal. See PCM PWR GND, SIG RTN & VREF TERMINAL IDENTIFICATION table. See WIRING DIAGRAMS article. If both resistance measurements are more than 10 k/ohms, replace PCM. If either resistance measurement is 10 k/ohms or less, repair short to ground in affected circuit.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 P0127: IAT2 Too High - Check Charge Air Cooler Pump Operation
Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC). Turn ignition switch to ON position. Using scan tool, select OUTPUT TEST MODE.Command ALL OUTPUTS ON. If Charge Air Cooler (CAC) pump runs, go to next step. If CAC pump does not run, go to TEST KP, step 1) . - 31) Check Intercooler System
Make the following visual inspections:- Intercooler Fluid Level
- Check For Cracked Coolant Lines
- Check For Blocked Heat Exchanger Or Coolant Lines
- Check For Crossed Coolant Lines
Repair as necessary. If intercooler system is okay, go to next step.
- 32) Simulate High IAT2 Voltage Signal
Ensure scan tool is connected to DLC. Turn ignition switch to ON position. Using scan tool, select IAT2 PID from PID/DATA MONITOR & RECORD menu. Monitor IAT2 PID voltage while disconnecting IAT2 sensor harness connector. If IAT2 PID voltage is more than 4 volts, go to next step. If IAT2 PID voltage is 4 volts or less, replace PCM. - 33) Simulate Low IAT2 Voltage Signal
Ensure ignition switch is turned to ON position. Monitor IAT2 PID voltage while connecting jumper wire between IAT2 sensor harness connector IAT2 signal and SIG RTN terminals. If IAT2 PID voltage is one volt or more, replace PCM. If IAT2 PID voltage is less than one volt, reconnect IAT2 sensor and go to appropriate PIN VOLTAGE/PID VALUE - INPUTS table in PIN VOLTAGE/PID VALUE CHARTS - TRUCKS article. Compare PID values from road test conditions for IAT2 with values in PIN VOLTAGE/PID VALUE - INPUTS table. If IAT2 sensor is not within range, replace IAT2 sensor.
NOTE:
Test procedure begins with step 10). No test procedures have been omitted.
NOTE:
If a communication link error is displayed, remove jumper wire and go to step 12).