Diagnostic Aids

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 when directed by QUICK TEST. This system test is intended to diagnose.

Barometric Pressure (BARO) Sensor
Wiring Harness Circuits (BARO SIG, SIG RTN & VREF)
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
P0106			DQ1
P0107			DQ1
P0108			DQ1
P0109			DQ1

1) DTC P0106, P0107, P0108 Or P0109

Obtain local barometric pressure reading. Turn ignition switch to ON position. Using scan tool, select BARO PID from PID/DATA MONITOR & RECORD menu. See BARO SENSOR SPECIFICATIONS table. If PID reading is comparable with local barometric pressure reading, unable to duplicate problem at this time, go to TEST Z . If PID reading is not comparable with local barometric pressure reading, perform the following:

For DTC P0108, go to step 7.
All others, go to next step.

BARO SENSOR SPECIFICATIONS

In. Hg	Volts	Frequency (Hz)
17.1	2.45	122.4
18.3	2.65	125.5
19.5	2.85	128.7
20.7	3.05	131.9
21.8	3.25	135.1
23.0	3.45	138.3
24.2	3.65	141.8
25.4	3.85	145.4
26.6	4.05	148.9
27.7	4.25	152.5
28.9	4.45	156.1
30.1	4.65	159.6
31.0	4.80	162.4

2) Check BARO Signal & SIG RTN Circuit For Open

Measure resistance of BARO circuit between PCM connector terminal No. 63 and BARO sensor. Measure resistance of SIG RTN circuit between PCM connector terminal No. 91 and BARO sensor. If resistance in both readings is less than 5 ohms, go to next step. If resistance in either reading is 5 ohms or more, repair open circuit.

3) Check VREF Voltage To BARO Sensor

Disconnect BARO sensor connector. Measure voltage between VREF and STG RTN terminals at BARO sensor harness connector. See Fig 1. If voltage is 4-6 volts, go to step 5. If voltage is not 4-6 volts, go to next step.

Fig 1: Identifying BARO Sensor Circuits & Connector Terminals
Courtesy of FORD MOTOR CO.

4) Check For Open VREF Circuit

Measure resistance between PCM connector terminal No. 90 and VREF terminal at BARO sensor harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit.

5) Check BARO Circuit For Short To Ground

Measure resistance between PCM connector terminals No. 63 and 91. Measure resistance between PCM connector terminal No. 63 and negative battery terminal. If both resistance readings are more than 10 k/ohms, go to next step. If any resistance reading is 10 k/ohms or less, repair short circuit.

6) Check VREF Circuit For Short To Ground

Measure resistance between PCM connector terminals No. 90 and 91. Measure resistance between PCM connector terminal No. 90 and negative battery terminal. If both resistance readings are more than 10 k/ohms, replace PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Program PCM. See FLASH VEHICLE IDENTIFICATION BLOCK PROCEDURE . If any resistance reading is 10 k/ohms or less, repair short circuit.

7) DTC P0108: Induce Opposite Code

Disconnect BARO sensor connector. Turn ignition switch to ON position. Check for DTCs. If DTC P0107 is present, replace BARO sensor. If DTC P0107 is not present, go to next step.

8) Check BARO Signal Circuit For Short TO Power

Measure resistance between PCM connector terminals No. 63 and 71 (VPWR). If resistance reading 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 reading is 10 k/ohms or less, repair short circuit.