Ford F150 Pickup. Instruction - part 1527

Fig. 265: Identifying EVAP System Components (LS & Thunderbird) 
Courtesy of FORD MOTOR CO. 

Fig. 266: Identifying EVAP System Components (Windstar) 
Courtesy of FORD MOTOR CO. 

Testing 

 

2003 Ford Pickup F150 

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

  

1) For Continuous Memory Only DTC P0443: Inspect EVAP Canister Purge Valve Circuit For 
Intermittent Failure 
DTC P0443 is set when EVAP Monitor test fails due to EVAP canister purge valve circuit signal reading 
outside minimum or maximum allowable calibrated parameters for a specified duty cycle PCM detects. 
Possible causes are: 

z

VPWR Circuit Open  

z

EVAP Canister Purge Valve Circuit Open, Or Shorted To GND Or VPWR  

z

Faulty EVAP Canister Purge Valve  

z

Faulty PCM  

Repeat KOEO ON-DEMAND SELF-TEST and KOER ON-DEMAND SELF-TEST . If DTC P0443 
is present in KOEO or KOER ON-DEMAND self-test, go to next step. If DTC P0443 is present in 
Continuous Memory only, check for intermittent faults. Go to TEST Z, step 1). If no faults are indicated, 
replace PCM. 

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

 

2003 Ford Pickup F150 

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

  

Fig. 267: Identifying EVAP Canister Purge Valve Circuits & Connector Terminals 
Courtesy of FORD MOTOR CO. 

2) For KOEO & KOER Only DTC P0443: Check VPWR Voltage To EVAP Canister Purge Valve 
Turn ignition switch to OFF position. Disconnect EVAP canister purge valve connector. Turn ignition 
switch to ON position. Using a DVOM, measure voltage between negative battery terminal and VPWR 
circuit at EVAP canister purge valve harness connector. See Fig. 267. If voltage is more than 10.5 volts, 
go to next step (for LS and Thunderbird). Or go to step 4) (for all others). If voltage is 10.5 volts or less, 

 

2003 Ford Pickup F150 

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

  

repair open in VPWR circuit. 

3) Check EVAP Canister Purge Valve Resistance (LS & Thunderbird) 
Turn ignition switch to OFF position. Ensure EVAP canister purge valve is disconnected. Using a 
DVOM, measure resistance between EVAP canister purge valve terminals. If resistance is 2.5-6.0 ohms, 
go to step 5). If resistance is not 2.5-6.0 ohms, replace EVAP canister purge valve. Perform 
EVAPORATIVE EMISSIONS SYSTEM LEAK TEST under SYSTEM TESTS (EVAPORATIVE 
EMISSION) to verify repair. 

4) Check EVAP Canister Purge Valve Resistance (Except LS & Thunderbird) 
Turn ignition switch to OFF position. Ensure EVAP canister purge valve is disconnected. Using a 
DVOM, measure resistance between EVAP canister purge valve terminals. If resistance is 30-38 ohms, 
go to next step. If resistance is not 30-38 ohms, replace EVAP canister purge valve. Perform 
EVAPORATIVE EMISSIONS SYSTEM LEAK TEST under SYSTEM TESTS (EVAPORATIVE 
EMISSION) to verify repair. 

5) Check EVAP Canister Purge Valve Circuit For Open In Harness 
 
Ensure ignition switch is turned to OFF position. Disconnect PCM connector(s). Inspect connector for 
loose, damaged or corroded terminals. Using a DVOM, measure resistance of EVAP canister purge valve 
circuit between PCM harness connector and EVAP canister purge valve harness connector. See PCM 
CONNECTOR IDENTIFICATION and Fig. 267. If resistance is less than 5 ohms, go to next step. If 
resistance is 5 ohms or more, repair open in EVAP canister purge valve circuit. 

6) Check EVAP Canister Purge Valve Circuit For Short To PWR GND In Harness 
 
Disconnect scan tool from DLC. Using a DVOM, measure resistance between negative battery terminal 
and EVAP canister purge valve circuit at EVAP canister purge valve harness connector. If resistance is 
10 k/ohms or less, repair short to PWR GND in EVAP canister purge valve circuit. If resistance is more 
than 10 k/ohms, go to next step. 

7) Check EVAP Canister Purge Valve Circuit For Short To VPWR In Harness 
 
Turn ignition switch to ON position. Using a DVOM, measure resistance between negative battery 
terminal and EVAP canister purge valve circuit at EVAP canister purge valve harness connector. If 
voltage is more than 10.5 volts, repair short to VPWR in EVAP canister purge valve circuit. If voltage is 
10.5 volts or less, replace PCM. 

NOTE:

EVAP canister purge valve resistance reading must be taken with engine 
cooled down.

NOTE:

EVAP canister purge valve resistance reading must be taken with engine 
cooled down.

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 6) to step 18). No test procedures have been omitted.

 

2003 Ford Pickup F150 

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