Ford F150 Pickup. Manual — part 1523

Fig. 255: Identifying SCVM Wiring Harness Connector Terminals (Ranger 2.3L)
Courtesy of FORD MOTOR CO.

Fig. 256: Identifying Intake Manifold Tuning Valve Actuator Harness Connector Terminals (Expedition
4.6L 2V & Expedition & Navigator 5.4L 4V)
Courtesy of FORD MOTOR CO.

2003 Ford Pickup F150

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

Fig. 257: Identifying Intake Manifold Tuning Valve (IMTV) Vacuum Solenoid Wiring Harness
Connector Terminals (Blackwood 5.3L, & Econoline & Pickup 4.6L)
Courtesy of FORD MOTOR CO.

Fig. 258: Identifying Intake Manifold Tuning Valve (IMTV) Vacuum Solenoid Wiring Harness
Connector Terminals (LS V6)
Courtesy of FORD MOTOR CO.

Testing

1) Check For Incorrect Idle Speed

Go to step 4) if directed here for a part throttle symptom.

Ensure engine is at normal operating temperature. Start engine and allow to idle for a minimum of one
minute. Using vehicle tachometer or scan tool, check idle speed. Access RPM PID and read engine speed.

2003 Ford Pickup F150

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

For RPM specifications, see PIN VOLTAGE/PID VALUE CHARTS in appropriate PIN VOLTAGE/PID
VALUE CHARTS article. If idle speed is correct, turn ignition switch to OFF position and go to next
step. If idle speed is high, ensure throttle arm fully returns and contacts return stop. Repair as necessary
and go to step 6). For other idle speed concerns, go to step 7).

2) Check For Sticking Or Binding Condition

Manually operate throttle from fully open to fully closed. Check for binding or sticking. If linkage sticks,
binds or grabs, go to next step. If linkage does not stick, bind or grab, go to step 4).

3) Isolate Sticking Or Binding Concern
Turn ignition switch to OFF position. Disconnect accelerator and speed control cables from throttle body.
Check operation of throttle body by rotating throttle body linkage. If throttle body linkage moves freely,
replace control cables. If throttle body linkage does not move freely, replace throttle body.

4) Check Functionality Of Throttle Position Sensor

Connect scan tool to Data Link Connector (DLC). Turn ignition switch to ON position. Using scan tool,
access TP V PID from PID/DATA MONITOR & RECORD menu. Monitor TP V PID voltage reading
while slowly depressing accelerator pedal from closed throttle position to Wide Open Throttle (WOT)
position. If TP V PID voltage reading increases smoothly during accelerator movement, go to next step. If
TP V PID voltage reading did not increase smoothly during accelerator movement, replace TP sensor.

5) Check For Air Cleaner Element & Inlet Restrictions

Check air filter and inlet tube for restrictions. Check for plugging or blockage through air inlet to throttle
body. Clean inlet and element or replace element as necessary. If air cleaner element and inlet tube are
okay, go to next step.

6) Check For Positive Crankcase Ventilation Concern
Check PCV valve connections for leaks or cracks. Remove PCV valve and check for plugged or incorrect
valve. Repair as necessary. If PCV valve is okay, go to step 9) (high idle concern), or reinstall PCV valve
and go to next step (all others).

7) Check For IAC Valve Response

Reconnect PCV valve if disconnected previously. Ensure all accessories are off. Ensure engine is at
operating temperature. Start engine and allow to idle for a minimum of one minute. Disconnect IAC

CAUTION: DO NOT attempt to clean throttle bore and plate area. Cleaning will

damage throttle body assembly.

NOTE:

Sticking or binding condition can be within cables or throttle body
assembly.

NOTE:

A high idle may indicate incorrect PCV valve size or a vacuum leak.

2003 Ford Pickup F150

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

solenoid harness connector. If engine idle speed decreases or engine almost stalls, go to next step. If
engine idle speed is low and does not change when disconnecting IAC solenoid, replace IAC solenoid. If
engine idle speed is high and does not change when disconnecting IAC solenoid, go to step 9).

8) Inspect Throttle Body Plate Hole For Plugging
Remove resonator from throttle body assembly. Inspect throttle plate hole for restriction. Repair as
necessary. If throttle plate hole is not restricted, return to appropriate symptom diagnosis in
SYMPTOMS in TROUBLE SHOOTING - NO CODES - CNG, FLEX-FUEL & GASOLINE article.

9) Check For Vacuum Leaks

Start engine and allow to idle. Listen for vacuum leaks. Inspect inlet air system from Mass Air Flow
(MAF) sensor to intake manifold for cracks, loose connections or faulty gaskets. Inspect intake manifold,
EGR gasket and diaphragm, seal to intake manifold and vacuum hoses for leaks. Repair as necessary. If
no faults are found, disconnect IAC valve harness connector. If idle speed does not drop, replace IAC
valve. If idle speed drops, go to next step.

10) Check Throttle Body For Excessive Wear

Turn ignition switch to OFF position. Remove throttle body. See THROTTLE BODY under FUEL
SYSTEMS in appropriate REMOVAL & INSTALLATION article. With throttle fully closed, hold
throttle body up to light source. Check for excessive gap between throttle bore and plate. Rotate throttle
lever to WOT and inspect bore for wear or grooving. If faults are present, replace throttle body. If throttle
body is okay, fault cannot be duplicated or identified at this time. Reinstall throttle body and return to
appropriate symptom diagnosis in TROUBLE SHOOTING - NO CODES - CNG & GASOLINE article.

15) For KOEO & Continuous Memory Only DTCs P1516, P1517, P2014 & P2019, & For KOEO,
KOER & Continuous Memory DTCs P1518-P1520, P1537, P1538, P2004-P2006 & P2008: Visual
Inspection

NOTE:

Not all applications are equipped with a throttle plate hole. If not equipped,
return to appropriate symptom diagnosis in SYMPTOMS in TROUBLE
SHOOTING - NO CODES - CNG, FLEX-FUEL & GASOLINE article.

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips
from step 10) to step 15). No test procedures have been omitted.

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

WARNING:

Be careful when operating IMRC or IMSC by hand. IMRC or IMSC
return springs are strong and may cause plates to close suddenly.

NOTE:

Focus 2.0L 2V, Econoline and Pickup 4.2L, and Ranger 2.3L are equipped
with electronic actuators. If the following visual inspection is not
necessary, go to step 17).

2003 Ford Pickup F150

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