Understanding your 2003 Ford Expedition’s electrical system is crucial for both routine maintenance and troubleshooting. Two key components in this system are the fuse box and the OBD2 port. Knowing their locations and functions can save you time and effort when diagnosing electrical issues or performing vehicle inspections. This guide will detail the location of the fuse box and provide a diagram, as well as guide you to the OBD2 port in your 2003 Ford Expedition.
The primary fuse box in your 2003 Ford Expedition, also known as the power distribution box or passenger compartment fuse panel, is situated inside the vehicle. You can find it conveniently located beneath the right-hand side of the instrument panel, making it accessible from the passenger side of the cabin.
Below is a detailed fuse box diagram and description for the passenger compartment fuse panel in your 2003 Ford Expedition. This table outlines the fuse number, amperage, and the circuits each fuse protects. Understanding this diagram is essential for identifying and replacing blown fuses, which can resolve many common electrical problems in your vehicle.
| № | A | Description |
|---|---|---|
| 1 | 7.5 | Run/Accessory – Front wiper motor, Instrument cluster, Rear wiper motor |
| 2 | 20 | Turn signal/Hazard flasher, Stoplamp switch, Stoplamps, Center high-mount stop light (CHMSL), Turn signal lamps |
| 3 | 7.5 | Power mirror switch, Power mirrors (non-memory), Driver seat switch (memory), Memory module (logic power) |
| 4 | 15 | DVD player, Rear seat audio controls, CDDJ (navigation radio) |
| 5 | 7.5 | Powertrain Control Module (PCM) (KA power), Speed control deactivation switch, Manual climate control mode switch, Stoplamp switch, Brake-shift interlock (BSI) solenoid, EATC control head, Body Security Module (BSM) (KA power), 3rd row seat relay coils, SecuriLock LED |
| 6 | 15 | Headlamp switch (parklamps and switch backlight feed), Parklamps, License plate lamps, Foglamp relay coil, Trailer tow electric brake controller (illumination), BSM (autolamp, parklamps) Foglamp indicator |
| 7 | 5 | Radio (start signal) |
| 8 | 10 | Rear window defroster switch, Rear window defroster indicator (climate control head), Heated outside mirrors |
| 9 | – | Not used |
| 10 | 20 | Trailer tow back-up lamps relay, Trailer tow 7–wire connector (back-up lamps), Trailer tow parklamp relay, Trailer tow 7– and 4–pin connectors (parklamps) |
| 11 | 10 | A/C compressor clutch relay, A/C compressor clutch solenoid, 4×4 Integrated Wheel Ends (IWE) solenoid |
| 12 | 15 | Fuel pump relay, Fuel pump shut-off switch, Fuel pump driver module, Fuel pump motor |
| 13 | 10 | Manual climate control mode switch, Rear window defroster relay coil, A/C refrigerant containment switch, A/C de-icing switch, A/C low pressure switch, DATC control head, DATC solenoids, DATC blower control, Trailer tow battery charge relay coil |
| 14 | 10 | Daytime Running Lamps (DRL) ignition relay coil, Digital Transmission Range Sensor (DTRS) back-up lamps, Trailer tow back-up lamps relay coil, Electrochromatic mirror, Manual A/C blend door actuator |
| 15 | 5 | AdvanceTrac® with RSC switch, Instrument cluster (Run/Start feed) |
| 16 | 10 | BS/AdvanceTrac® with RSC module (Run/Start feed) |
| 17 | 15 | Foglamps |
| 18 | 10 | Auxiliary A/C temperature blend door actuator, Auxiliary A/C front auxiliary control, Turn signal flasher, Electrochromatic mirror, Auxiliary mode motor |
| 19 | 10 | Restraints Control Module (RCM) |
| 20 | 30 | BSM (door locks, liftgate glass release relay), Liftgate glass release motor, Door/Liftgate lock motors |
| 21 | 15 | Instrument cluster (B+), Interior (courtesy) lamps, Puddle lamps (outside mirrors) |
| 22 | 10 | Moonroof switch illumination, Radio (delayed accessory feed), Flip window switch, Flip window motors, EHAM antenna amplifier (navigation radio) |
| 23 | 10 | RH low beam |
| 24 | 15 | Interior demand lamps (front map/dome lamp, 2nd row dome/map lamp, glove compartment lamp, cargo lamp, roof rail lamps, vanity mirror lamps), Battery saver relay coil, Battery saver relay power, Heated Positive Crankcase Ventilation (PCV) valve |
| 25 | 10 | LH low beam |
| 26 | 20 | Horn relay, Horns |
| 27 | 5 | Compass module, Reverse sensing system module, Brake shift interlock solenoid, Overdrive cancel switch, Air suspension module (Run/Start sense) |
| 28 | 5 | PCM relay coil, SecuriLock transceiver, Heated PCV valve relay coil |
| 29 | 30 | Trailer tow electric brake controller, Trailer tow 7–wire connector (electric brake) |
| 30 | 25 | Air suspension module (air spring solenoids and height sensors), PCM (4×4 transfer case clutch) |
| 31 | 20 | Radio (B+), Subwoofer |
| 32 | 15 | Catalyst Monitor Sensors (CMS), Transmission solenoids, Canister vent solenoid, HEGO sensors, VMV solenoid, A/C compressor clutch relay coil, CMCV, VCT actuators |
| 33 | – | Not used |
| 34 | 15 | PCM, Fuel injectors, Mass Air Flow (MAF) sensor |
| 35 | 20 | Instrument cluster high beam indicator, High beam headlamps |
| 36 | 10 | Trailer tow right turn/stop lamps |
| 37 | 20 | Cargo area power point |
| 38 | 25 | Rear wiper motor, Washer pump (rear window wash) |
| 39 | 20 | Console power points (front and rear of console), Instrument panel power point (bench seat) |
| 40 | 20 | DRL relays, DRL foglamps, DRL headlamp relay coil, Headlamp switch (headlamps), Multifunction switch (flash-to-pass), BSM (autolamp headlamps relay), High beam relay coil, Fuse 25 (LH low beam), Fuse 23 (RH low beam) |
| 41 | 20 | Cigarette lighter, OBD II diagnostic connector |
| 42 | 10 | Trailer tow left turn/stop lamps |
| 101 | 30 | Starter motor relay, Starter motor solenoid |
| 102 | 30 | Ignition switch power |
| 103 | 30 | ABS/AdvanceTrac® with RSC module (pump motor) |
| 104 | 30 | LH 3rd row seat relay, LH 3rd row seat switch, LH 3rd row seat motor |
| 105 | 30 | Spare |
| 106 | 30 | Trailer tow battery charge relay, Trailer tow 7–way connector (battery charge) |
| 107 | 30 | Auxiliary A/C blower relay, Auxiliary A/C blower motor |
| 108 | 30 | Passenger seat motor switch |
| 109 | 30 | Driver seat motor switch (non-memory), Memory module, Power memory mirrors, Adjustable pedals switch and motor |
| 110 | 30 | Spare |
| 111 | 50 | Air suspension compressor, Air suspension compressor relay |
| 112 | 30 | ABS/AdvanceTrac® with RSC module (valves) |
| 113 | 30 | Front wiper motor, Washer pump (windshield wash) |
| 114 | 40 | Rear window defroster relay, Rear window defroster grid, Heated mirrors (Fuse 8) |
| 115 | 30 | Transfer case shift motor, 4×4 relays |
| 116 | 40 | Front blower motor relay, Front blower motor |
| 117 | 30 | RH 3rd row seat relay, RH 3rd row seat switch, RH 3rd row seat motor |
| 118 | 30 | Driver and passenger climate control seat module |
| 401 | 30 | Power windows (circuit breaker), Main window switch, Window motors, Window switches, Moonroof module |
| R01 | Starter relay: Starter motor solenoid | |
| R02 | Delayed accessory relay: Fuse 22, CB 401, Power windows, Switch backlighting, Radio, Moonroof, Flip windows, Navigation antenna amplifier | |
| R03 | Hi-beam relay: Fuse # 35, Hi-beam headlamps, Hi-beam indicator | |
| R04 | Rear window defrost relay: Fuse 8 (heated mirrors), Rear window defroster, Heated outside mirrors, Rear window defroster indicator (climate control head) | |
| R05 | Trailer tow battery charge relay: Trailer tow 7–wire connector (battery charge) | |
| R06 | Front blower relay: Front blower motor | |
| R201 | Trailer tow park lamp relay: Trailer tow 7–wire and 4–wire connectors (park lamps) | |
| R202 | Foglamp relay: Front foglamps | |
| R203 | PCM relay: Fuse 32, Fuse 34, PCM solenoids and sensors | |
| R301 | Trailer tow back-up lamp relay: Trailer tow 7–wire connector (back-up lamps) | |
| R302 | Heated PCV valve relay: Heated PCV valve | |
| R303 | Fuel pump relay: Fuel pump shut-off switch, PCM (fuel pump monitor), Fuel pump, Fuel pump driver module | |
| R304 | Battery saver relay: Roof rail lamps, Vanity mirror lamps, Map/Dome lamp, Glove box lamp, Cargo area lamp, Outside mirror puddle lamps, Instrument cluster (interior lamps) | |
| R305 | Horn relay: Dual note horn |
Locating the OBD2 Port in Your 2003 Ford Expedition
The On-Board Diagnostics II (OBD2) port is a standardized connector used to access your vehicle’s computer system for diagnostics and monitoring. For the 2003 Ford Expedition, the OBD2 port is typically located under the dashboard on the driver’s side. You’ll usually find it near the steering column or slightly to the left, in the vicinity of the pedals.
This port is crucial for connecting scan tools to read diagnostic trouble codes (DTCs), check engine lights, and access real-time vehicle data. If you’re experiencing issues with your 2003 Ford Expedition, connecting an OBD2 scanner to this port is often the first step in diagnosing the problem.
Fuse 41 and the OBD2 Port
It’s worth noting from the fuse diagram that Fuse 41 (20A) is designated for the “Cigarette lighter, OBD II diagnostic connector”. If you are having trouble getting a reading from your OBD2 port, or if your scan tool is not powering up when connected, checking Fuse 41 in the passenger compartment fuse box should be one of your initial troubleshooting steps. A blown fuse here can directly interrupt power to the OBD2 port, preventing communication with diagnostic tools.
By understanding both the fuse box layout and the OBD2 port location in your 2003 Ford Expedition, you are better equipped to maintain your vehicle and address potential electrical or diagnostic issues effectively. This knowledge empowers you to perform basic troubleshooting and communicate more effectively with automotive professionals when needed.
