Ford F150 Pickup. Instruction - part 1461

4) Check VREF Voltage Through PCM On TP PID 
Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC). Using scan tool, 
access PID/DATA MONITOR & RECORD menu. See PARAMETER IDENTIFICATION MODE 
under ADDITIONAL SYSTEM FUNCTIONS. Using scan tool, access VPWR PID from PID/DATA 
MONITOR & RECORD menu. If scan tool is able to access VPWR PID, check VREF circuit for open. 
Go to step 20). For 122-pin and 150-pin PCM harness connectors, disconnect the sensor where the DTC 
indicates a failure, and go to step 16). If scan tool is unable to access TP PID, go to next step to check 
VPWR and VREF for shorts. 

5) Check VPWR Voltage To Injector 
 
Turn ignition switch to OFF position. Disconnect injector electrical connector (any injector easily 
accessed). Turn ignition switch to ON position. Using a DVOM, measure voltage between VPWR 
terminal at injector harness connector and negative battery terminal. If voltage is 10.5 volts or less, 
VPWR is not present. Reconnect connectors and go to TEST X, step 1) (power relay inside CCRM), or 
go to TEST B, step 1) (all others). If voltage is more than 10.5 volts, go to next step. 

6) Check For Short Between VREF Circuit & SIG RTN Circuit In TP Or ETC TP Sensor 
Disconnect TP sensor harness connector. Turn ignition switch to ON position. Using a DVOM, measure 
voltage between SIG RTN terminal and VREF terminal at TP sensor harness connector. If voltage is 4-6 
volts, turn ignition switch to OFF position and replace TP sensor or ETC TP sensor. If voltage is not 4-6 
volts, go to next step. 

7) Check For Short Between VREF Circuit & SIG RTN Circuit In DPFE, ESM or TMAP Sensor 
Ensure TP sensor is disconnected. Disconnect DPFE, ESM or TMAP sensor. Turn ignition switch to ON 
position. Using a DVOM, measure voltage between SIG RTN terminal and VREF terminal at TP sensor 
harness connector. If voltage is 4-6 volts, turn ignition switch to OFF position and replace DPFE, ESM or 
TMAP sensor. If voltage is not 4-6 volts, go to next step. 

8) Check For Short Between VREF Circuit & SIG RTN Circuit In FTP Sensor 
Ensure TP sensor and DPFE or ESM or TMAP sensor are disconnected. Disconnect FTP sensor. Turn 
ignition switch to ON position. Using a DVOM, measure voltage between SIG RTN terminal and VREF 
terminal at TP sensor harness connector. If voltage is 4-6 volts, turn ignition switch to OFF position and 
replace FTP sensor. If voltage is not 4-6 volts, go to next step. 

accessed even though a fault exists.

NOTE:

Electronic Throttle Control (ETC) applications name VREF as ETCREF, and 
SIGRTN as ETCRTN.

NOTE:

If vehicle is not equipped with DPFE, ESM or TMAP sensor, go to step 8). 
For sensor applications, see SENSORS CONNECTED TO VREF CIRCUIT 
table.

NOTE:

If vehicle is not equipped with an FTP sensor, go to step 9).

 

2003 Ford Pickup F150 

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

  

9) Check For Short Between VREF Circuit & SIG RTN Circuit In ACP Sensor 
Ensure DPFE or ESM or TMAP sensor, TP and FTP sensors are disconnected. Disconnect ACP sensor. 
Turn ignition switch to ON position. Using a DVOM, measure voltage between SIG RTN terminal and 
VREF terminal at TP sensor harness connector. If voltage is 4-6 volts, turn ignition switch to OFF 
position and replace ACP sensor. If voltage is not 4-6 volts, go to next step. 

10) Check For Short Between VREF Circuit & SIG RTN Circuit In PSP Sensor 
Ensure DPFE or ESM or TMAP sensor, TP, FTP and ACP sensors are disconnected. Disconnect PSP 
sensor. Turn ignition switch to ON position. Using a DVOM, measure voltage between SIG RTN 
terminal and VREF terminal at TP sensor harness connector. If voltage is 4-6 volts, turn ignition switch to 
OFF position and replace PSP sensor. If voltage is not 4-6 volts, go to next step. 

11) Check For Short Between VREF Circuit & SIG RTN Circuit In FRP Sensor 
Ensure DPFE or ESM or TMAP sensor, TP, FTP, ACP and PSP sensors are disconnected. Disconnect 
FRP sensor. Turn ignition switch to ON position. Using a DVOM, measure voltage between SIG RTN 
terminal and VREF terminal at TP sensor harness connector. If voltage is 4-6 volts, turn ignition switch to 
OFF position and replace FRP sensor. If voltage is not 4-6 volts, go to next step. 

12) Check For Short Between VREF Circuit & SIG RTN Circuit In BARO Or MAP Sensor 
Turn ignition switch to OFF position. Leave all previously disconnected sensors disconnected. 
Disconnect BARO or MAP sensor. Turn ignition switch to ON position. Using a DVOM, measure 
voltage between SIG RTN terminal and VREF terminal at TP sensor harness connector. If voltage is 4-6 
volts, turn ignition switch to OFF position and replace BARO or MAP sensor. If voltage is not 4-6 volts, 
go to next step. 

13) Check For Short Between VREF Circuit & SIG RTN Circuit In SVCM Sensor 
Turn ignition switch to OFF position. Leave all previously disconnected sensors disconnected. 
Disconnect SVCM sensor. Turn ignition switch to ON position. Using a DVOM, measure voltage 
between SIG RTN terminal and VREF terminal at TP sensor harness connector. If voltage is 4-6 volts, 
turn ignition switch to OFF position and replace SVCM sensor. If voltage is not 4-6 volts, go to next step. 

14) Check VREF Circuit Short To SIG RTN In APP Sensor 
Turn ignition switch to OFF position. Leave all previously disconnected sensors disconnected. 

NOTE:

If vehicle is not equipped with an ACP sensor, go to step 10).

NOTE:

If vehicle is not equipped with a PSP sensor, go to step 11).

NOTE:

If vehicle is not equipped with a FRP sensor, go to step 12).

NOTE:

If vehicle is not equipped with a BARO or MAP sensor, go to step 13).

NOTE:

If vehicle is not equipped with a SVCM sensor, go to step 14).

NOTE:

If vehicle is not equipped with a APP sensor, go to step 15).

 

2003 Ford Pickup F150 

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

  

Disconnect APP sensor. Turn ignition switch to ON position. Using a DVOM, measure voltage between 
SIG RTN terminal and VREF terminal at ETC TP sensor harness connector. If voltage is 4-6 volts, turn 
ignition switch to OFF position and replace APP sensor. If voltage is not 4-6 volts, go to next step. 

15) Check VPWR Voltage to PCM 
 
Turn ignition switch to OFF position. Leave all previously disconnected sensors disconnected. 
Disconnect PCM connector(s). Turn ignition switch to ON position. Using a DVOM, measure voltage 
between VPWR and PWR GND circuits at PCM harness connector terminals. See WIRING 
DIAGRAMS. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, turn 
ignition switch to OFF position and repair open in VPWR circuit between PCM and splice to injector 
harness connector. 

16) Check VREF For Short To Ground Or SIG RTN 
 
Turn ignition switch to OFF position. Ensure all sensors wired to VREF are disconnected. Ensure PCM is 
disconnected. Disconnect scan tool from Data Link Connector (DLC). Using a DVOM, measure 
resistance between specified PCM harness connector VREF terminal and PWR GND and SIG RTN 
terminals. See PCM PWR GND, SIG RTN & VREF TERMINAL IDENTIFICATION table. If any 
resistance measurement is 10 k/ohms or less, repair VREF short to ground. If directed to this step from 
step 4), and all resistance measurements are more than 10 k/ohms, go to step 5). For all others, if all 
resistance measurements are more than 10 k/ohms, replace PCM. 

PCM PWR GND, SIG RTN & VREF TERMINAL IDENTIFICATION 

Application

Measure Between PCM VREF Terminal No. & PWR GND, &

SIG RTN Terminals No.

Aviator

B20 & E20 (VREF), & B24, B25, B26, B27 & B43 (PWR GND), &

B17, E17 & T17 (SIG RTN)

Blackwood & F150 Pickup (4.6L 
& 5.4L, & 5.4L NGV)

90 (VREF), & 3, 25, 51, 76 & 103 (PWR GND), & 91 (SIG RTN)

Crown Victoria, Grand Marquis, 
Marauder & Town Car

90 (VREF) & 3, 51, 76 & 103 (PWR GND), & 91 (SIG RTN)

Econoline

4.2L

90 (VREF), & 24, 25, 51, 76, 77 & 103 (PWR GND), & 91 (SIG

RTN)

4.6L

90 (VREF) & 3, 24, 25, 51, 76, 77 & 103 (PWR GND), & 91 (SIG

RTN)

5.4L

90 (VREF) & 3, 24, 51, 76, 77 & 103 (PWR GND), & 91 (SIG

RTN)

5.4L NGV

90 (VREF), & 3, 24, 25, 51, 77 & 103 (PWR GND), & 91 (SIG

RTN)

6.8L

90 (VREF), & 3, 23, 24, 25, 51, 76, 77 & 103 (PWR GND), & 91

(SIG RTN)

Escape

2.0L

90 (VREF), & 23, 24, 25, 33 (M/T), 51, 76, 77 & 103 (PWR

 

2003 Ford Pickup F150 

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

  

20) Check VREF Circuit For Open In Harness 
 
Turn ignition switch to OFF position. Ensure sensor is disconnected where VREF check failed. 
Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as 
necessary. Using a DVOM, measure resistance of VREF circuit between PCM harness connector and 
suspect sensor harness connector. See WIRING DIAGRAMS. If resistance is less than 5 ohms, replace 
PCM. If resistance is 5 ohms or more, repair open in VREF circuit. 

GND), & 91 (SIG RTN)

3.0L

90 (VREF), & 3, 24, 25, 51, 76 & 103 (PWR GND), & 91 (SIG

RTN)

Excursion & F250-F550 Super 
Duty (5.4L & 6.8L)

90 (VREF), & 3, 23, 24, 25, 51, 76, 77 & 103 (PWR GND), & 91

(SIG RTN)

Expedition & Navigator

B45 & E36 (VREF), & B1, B10, B11 & B23 (PWR GND), & B30,

B33, E25, E30 & T27 (SIG RTN)

Explorer & Mountaineer

A20 & C20 (VREF), & B24, B25, B26, B27 & B43 (PWR GND), &

A17, B17 & C17 (SIG RTN)

Explorer Sport, Explorer Sport 
Trac & F150 Pickup (4.2L)

90 (VREF), & 24, 25, 51, 76, 77 & 103 (PWR GND), & 91 (SIG

RTN)

Focus

2.0L SPI

90 (VREF), & 24, 25, 51, 77 & 103 (PWR GND), & 91 (SIG

RTN)

2.0L ZETEC

90 (VREF), & 24, 25, 51, 76, 77 & 103 (PWR GND), & 91 (SIG

RTN)

2.0L DURATEC

90 (VREF), & 23, 24, 25, 51, 77 & 103 (PWR GND), & 91 (SIG

RTN)

2.3L PZEV

E40 (VREF), & B47, B48 & B49 (PWR GND), & B41, E41 &

T41 (SIG RTN)

F150 Pickup (Lightning 5.4L SC)

90 (VREF), & 3, 25, 51, 77 & 103 (PWR GND), & 91 (SIG RTN)

LS

A20, A23, A55 A57, C14 & C20 (VREF), & A24, A25, A26, A27 &

A43 (PWR GND), & A5, A17, A38, B14, C15 & C17 (SIG RTN)

Mustang (3.8L)

90 (VREF) & 25, 51, 76, 77 & 103 (PWR GND), & 91 (SIG RTN)

Mustang (4.6L)

38, 90 (VREF) & 3, 25, 51, 76 & 103 (PWR GND), & 91 (SIG RTN)

Ranger, Sable & Taurus

90 (VREF), & 24, 25, 51, 76, 77 & 103 (PWR GND), & 91 (SIG

RTN)

Thunderbird

B13, B20, B23, B55, B57, E14 & E24 (VREF), & B24, B25, B26,

B27 & B43 (PWR GND), & B5, B17, B38, E15, E17 & T17 (SIG

RTN)

Windstar

90 (VREF), & 3, 24, 51, 76 & 103 (PWR GND), & 91 (SIG RTN)

ZX2 (2.0L)

90 (VREF), & 24, 33, 51, 77 & 103 (PWR GND), & 91 (SIG RTN)

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 16) to step 20). No test procedures have been omitted.

 

2003 Ford Pickup F150 

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