Ford F150 Pickup. Instruction — part 1483

BARO PID readings with specifications in BARO SENSOR SPECIFICATIONS table. If BARO PID
value is within specification, concern is not present at this time, go to TEST Z, step 1). If BARO PID
value is not within specification, go to next step. If BARO PID value is not within specification and DTC
P0108 was retrieved, go to step 7).

2) Check VREF Voltage To BARO Sensor

Disconnect BARO sensor connector. Using a DVOM, measure voltage between VREF and SIG RTN
circuits at BARO sensor harness connector. See Fig. 202. If voltage is 4-6 volts, go to step 5). If voltage
is not 4-6 volts, go to next step.

3) Check VREF Circuit For Open

Using a DVOM, measure resistance of VREF circuit between PCM harness connector and BARO sensor
harness connector. See Fig. 202. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms
or more, repair open VREF circuit.

4) Check For VREF Circuit Short To Ground

Using a DVOM, measure resistance between VREF circuit, and SIG RTN circuit at PCM harness
connector, and negative battery terminal. See Fig. 202. If either resistance measurement is 10 k/ohms or
less, repair short in affected circuit. If both resistance measurements are more than 10 k/ohms, go to next
step.

5) Check BARO SIG & SIG RTN Circuit For Open

Using a DVOM, measure resistance of BARO SIG and SIG RTN circuits between PCM harness
connector and BARO sensor harness connector. See Fig. 202. If either resistance measurement is 5 ohms
or more, repair open circuit. If both resistance measurements are less than 5 ohms, go to next step.

6) Check BARO Circuit For Short To Ground

Using a DVOM, measure resistance between BARO circuit, and SIG RTN circuit at PCM harness
connector, and negative battery terminal. See Fig. 202. If both resistance measurements are more than 10
k/ohms, replace BARO sensor. If concern is still present, replace PCM. If either resistance measurement
is 10 k/ohms or less, repair short in affected 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 SIG For Short To Power

Turn ignition switch to OFF position. Using a DVOM, measure resistance between BARO SIG and
VPWR circuits at PCM harness connector. See Fig. 202. If resistance measurement is more than 10
k/ohms, replace PCM. If resistance measurement is 10 k/ohms or less, repair short to VPWR in BARO

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline

SIG circuit.

TEST DR: CAMSHAFT POSITION SENSOR

Diagnostic Aids

CMP signal provides PCM information for fuel injector synchronization. The CMP signal originates from
Camshaft Position (CMP) sensor. Enter this system test only when instructed during QUICK TEST. This test is
only intended to diagnose the following:

z

Faulty CMP Sensor

z

Wiring Harness Circuits (CMP, CMP/TSS GND, PWR GND, SIG RTN & VPWR)

z

Faulty Powertrain Control Module (PCM)

Fig. 203: Identifying CMP Sensor Circuits & Connector Terminals (Econoline & Pickup 4.2L)
Courtesy of FORD MOTOR CO.

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.

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline

Fig. 204: Identifying CMP Sensor Circuits & Connector Terminals (Explorer & Mountaineer With 104-
Pin PCM)
Courtesy of FORD MOTOR CO.

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline

Fig. 205: Identifying CMP Sensor Circuits & Connector Terminals (Aviator, Expedition, Explorer &
Mountaineer With 150-Pin PCM, LS 3.9L, Navigator & Thunderbird)
Courtesy of FORD MOTOR CO.

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline