29) Check Voltage Between VREF & SIG RTN Circuits At FTP Sensor
Ensure ignition switch is turned to ON position. Using a DVOM, measure voltage between VREF and
SIG RTN circuits at FTP sensor harness connector. See Fig. 268 or Fig. 269 . If voltage is 4-6 volts, go to
next step. If voltage is not 4-6 volts, VREF voltage is out of range. Go to TEST C, step 1).
30) Check FTP Circuit For Short To SIG RTN Or PWR GND In Harness
Turn ignition switch to OFF position. Disconnect PCM connector(s). Inspect connector for loose,
damaged or corroded terminals. Disconnect scan tool from DLC. Using a DVOM, measure resistance
between FTP circuit, and SIG RTN circuit at PCM harness connector, and battery negative cable. 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 SIG RTN or PWR GND circuit in FTP circuit.
33) For KOEO, KOER & Continuous Memory DTC P0453: Check For High FTP Sensor Voltage
DTC P0453 is set when PCM detects Fuel Tank Pressure (FTP) sensor input signal exceeds maximum
allowable parameter of 4.5 volts. Possible causes are:
z
FTP Circuit Open
z
VREF Shorted To VPWR
z
Faulty Powertrain Control Module (PCM)
z
FTP Circuit Shorted To VREF Or VPWR
z
SIG RTN Circuit Open
z
Faulty FTP Sensor
Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC). Turn ignition
switch to ON position. Using scan tool, access FTP V PID from PID/DATA MONITOR & RECORD
menu. If FTP V PID is not available on scan tool, measure voltage by backprobing between FTP and SIG
RTN circuits at PCM harness connector. See PCM CONNECTOR IDENTIFICATION and Fig. 268 or
Fig. 269 . If voltage measurement on DVOM or PID voltage is more than 4.5 volts, go to next step. If
voltage is 4.5 volts or less, DTC P0453 is intermittent. Check for intermittent faults. Go to TEST Z, step
1).
34) Check FTP Circuit For Short To VPWR
Turn ignition switch to OFF position. Disconnect FTP sensor connector. Turn ignition switch to ON
position. Using a DVOM, measure voltage between negative battery terminal and FTP circuit at FTP
NOTE:
A break in step numbering sequence occurs at this point. Procedure skips
from step 30) to step 33). No test procedures have been omitted.
NOTE:
For additional testing information, see DIAGNOSTIC AIDS.
NOTE:
FTP sensor input with no pressure or vacuum on fuel tank should be 2.37-
2.97 volts.
2003 Ford Pickup F150
2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline