2003 ford expedition locker malfunction

If the RFW lock light is stuck on in Your Ford Ranger that means that the differential locker is not working properly. The system is operated by a vacuum line and that is the most common problem. If this vacuum line becomes loose or damaged it may lead to Your diff locker being stuck engaged. A rear differential locker is used in Your truck to lock the rear axle and make both wheels turn while You drive. This can be very useful when You have limited traction like in snowy or off road conditions. This system engages using vacuum pressure when it detects that one wheel is slipping so that it can give power to both wheels.

The information you are asking for varies depending on how the vehicle is equipped ie. ENGINE SIZE, AUTOMATIC or MANUAL TRANSMISSION, 2-WHEEL DRIVE, 4-WHEEL DRIVE, ALL-WHEEL DRIVE, etc.
With that said, it also deserves mention that there is a Technical Service Bulletin published by Ford Motor Company that applies to the model year and model that you have listed that involves Diagnostic Test Code (DTC) P0456.

Please note that this bulletin emphasizes the requirement of special equipment to properly diagnose and repair the DTC's listed in the bulletin. Below is a brief (partial) description of the bulletin:

Article No.
03-20-3
10/13/03
DRIVEABILITY - MALFUNCTION INDICAOR LAMP
(MIL) ILLUMINATED WITH DTC'S P0442, P0455,
P0456, P0457, P1442 OR CHECK FUEL CAP LAMP
ILLUMINATED WITH DTC P0457
FORD: 1997-2000 CONTOUR 1997-2002 ESCORT 1997-2003 CROWN VICTORIA, MUSTANG, TAURUS 1998-2003 ESCORT ZX2 2000-2003 FOCUS 2002-2003 THUNDERBIRD1997 F-250 HD
1997-1999 F-250 LD
1997-2003 E SERIES, EXPEDITION, EXPLORER, F-150, RANGER, WINDSTAR
1999-2003 F SUPER DUTY
2000-2003 EXCURSION
2001-2003 ESCAPE, EXPLORER SPORT TRAC, EXPLORER SPORT
LINCOLN:
1997-1998 MARK VIII
1997-2002 CONTINENTAL
1997-2003 TOWN CAR
2000-2003 LS
1998-2003 NAVIGATOR
2002-2003 BLACKWOOD
MERCURY:
1997-1999 TRACER
1997-2000 MYSTIQUE
1997-2003 GRAND MARQUIS, SABLE
1999-2002 COUGAR
1997-2003 MOUNTAINEER
This article supersedes TSB 03-9-8 to update the vehicle lines and Service Procedures.
ISSUE
Some vehicles may exhibit a Malfunction Indicator Lamp (MIL) illuminated with Diagnostic Trouble Codes (DTCs) P0442, P0455, P0456, P0457 or P1442 or a "Check Fuel Cap" Lamp illuminated with DTC P0457 for the Evaporative Emission System. This may be caused by loose or leaking hoses, loose or broken fuel cap, a leak at the top of the fuel filler pipe neck, etc.
ACTION
Use the Rotunda Leak Detector Smoke Machine (Part 218-00001) or equivalent, to locate and repair leaks in the Evaporative Emission System.

You can easily tell if you have 4wd by looking under the suv to see if there is a transfer case o nthe rear of the transmission as well as a driveshaft going to a front axle.

if it is the breather it will have a end on it so dirt won't get in, also check for cracks around where your vacuum lines connect to t's and y's they dry out on the ends. it could also be the vacuum actulator.

Possible solution..Expedition uses a vacuum solenoid on the firewall that controls vacuum to the 4-wheel drive actuator. Vacuum "unlocks" the 4-wheel drive, so you may have a leak in the line to the actuator so the 4-wheel drive is always on. Seems backwards, I know.

sounds like water in gas. add gas line antifreeze. 2 bottleshould do it.

Thank you for this tip. There are a lot of 4x4 that use vacuum to engage the front drive.

It does sound like a vacuum problem. Check vacuum hoses under the hood especially to vacuum reservoir cannister. Sounds like a hose is loose or leaking.

You can check the vacuum lines and diaphram that are located underneath the battery shelf. Comes out really easy. Check that the lines are not broken. There is a vacuum line that runs to a solenoid in the center of the fire wall, make sure they are not broken there, and there is an actuator cable that runs to the transfer case. Sometimes it is as easy as replacing the vacuum hose, the actuator cable, or the diaphram under the battery shelf went bad. If you ever had a battery leak acid because it went bad.....that acid goes under the shelf and eats those lines. Hope this helps.

The four wheel drive systems in these vehicles are simple. The push button controls the four wheel drive computer. The computer tells the encoder motor (on transfer case) to shift. When the transfer case shifts there is a vaccum switch on the transfer that is activated which sends vaccum to the accuator under the battery. The accuator pulls a cable to lock the front axle in. This covers all s series trucks and suv's with push button four wheel drive but not with auto or all wheel. Now to answer some questions. If your push button is lit up but will not go in to four high you should try to reset the four wheel drive computer. To reset pull the courtesy light and atc fuses for sixty seconds install fuses then cycle key on and off 5 times. If your transfer case shifts but your front end does not lock in check for vaccum at the switch on the transfer case in and out. If no vaccum out replace switch motormite number 49315 at parts store. If you have vaccum out check accuator.