Passenger compartment fuse panel / power distribution box diagram for 2004 Ford F-150, highlighting potential OBD2 related fuses like diagnostic connector and PCM fuses.
Passenger compartment fuse panel / power distribution box diagram for 2004 Ford F-150, highlighting potential OBD2 related fuses like diagnostic connector and PCM fuses.

2004 F-150 OBD2 Fuse Location: Troubleshooting and Diagrams

Understanding the fuse box locations and diagrams in your 2004 Ford F-150 is crucial for diagnosing and resolving electrical issues, especially those related to your OBD2 port. While the original diagrams for the 2004 F-150 detail various fuse locations, pinpointing the fuse related to your OBD2 (On-Board Diagnostics II) port is essential for quick troubleshooting.

This guide provides a comprehensive overview of the fuse box locations in your 2004 Ford F-150 and helps you identify potential fuses that could affect your OBD2 port’s functionality.

Your 2004 Ford F-150 is equipped with three distinct fuse boxes:

Passenger Compartment Fuse Panel

This fuse box is generally the first place to check for issues related to interior electrical components and often includes fuses relevant to the OBD2 port. It is typically located inside the cabin of your F-150.

Here is a detailed diagram of the passenger compartment fuse panel:

Type No. Description
Fuse MINI 10A 1 Run/Accessory – Wipers, Instrument cluster
Fuse MINI 20A 2 Stop/Turn lamps, Speed control deactivate switch
Fuse MINI 5A 3 Power mirrors, Memory logic power, Memory seats and pedals
Fuse MINI 10A 4 DVD battery power
Fuse MINI 5A 5 Keep alive memory for Powertrain Control Module (PCM) and climate control module
Fuse MINI 15A 6 Parklamps, BSM, Instrument panel illumination
Fuse MINI 5A 7 Radio (start signal)
Fuse MINI 10A 8 Heated mirrors, Switch indicator
Fuse MINI 20A 10 Trailer tow back-up lamps relay (PCB1), Trailer tow parklamp relay (R201)
Fuse MINI 10A 11 A/C clutch, 4×4 solenoid
Fuse MINI 10A 13 Climate control module power
Fuse MINI 10A 14 Back-up lamp and Daytime Running Lamps (DRL) relay coil, A/C pressure switch, Brake-shift interlock solenoid
Fuse MINI 5A 15 Overdrive cancel, Cluster, Brake-Shift Interlock (BSI)
Fuse MINI 10A 16 ABS module (Run/Start power)
Fuse MINI 15A 17 Fog lamp relay (R202)
Fuse MINI 10A 18 Run/Start feed – Flasher relay, Electrochromatic mirror, Heated seats, BSM, Compass, RSS (Reverse Sensing System)
Fuse MINI 10A 19 Restraints (Air bag module)
Fuse MINI 15A 20 PCM 4×4 power
Fuse MINI 15A 21 Cluster keep alive power
Fuse MINI 10A 22 Delayed accessory power for audio, power door lock switch and moonroof switch illumination
Fuse MINI 10A 23 RH low beam headlamp
Fuse MINI 15A 24 Battery saver power for demand lamps
Fuse MINI 10A 25 LH low beam headlamp
Fuse MINI 20A 26 Horn relay (PCB3), Horn power
Fuse MINI 5A 27 Passenger Air bag Deactivation (PAD) warning lamp, Cluster air bag warning lamp, Cluster RUN /START power
Fuse MINI 5A 28 SecuriLock transceiver (PATS)
Fuse MINI 15A 29 PCM 4×4 power
Fuse MINI 20A 31 Radio power
Fuse MINI 15A 32 Vapor Management Valve (VMV), A/C clutch relay, Canister vent, Heated Exhaust Gas Oxygen (HEGO) sensors #11 and #21, CMCV, Mass Air Flow (MAF) sensor, VCT
Fuse MINI 15A 33 Shift solenoid, CMS #12 and #22
Fuse MINI 20A 34 Fuel injectors and PCM power
Fuse MINI 20A 35 Instrument cluster high beam indicator, High beam headlamps
Fuse MINI 10A 36 Trailer tow right turn/stop lamps
Fuse MINI 20A 37 Rear power point
Fuse MINI 25A 38 Subwoofer power
Fuse MINI 20A 39 Instrument panel power point
Fuse MINI 20A 40 Low beam headlamps, DRL
Fuse MINI 20A 41 Cigar lighter, Diagnostic connector power
Fuse MINI 10A 42 Trailer tow left turn/stop lamps
Fuse FMX/JCase 30A 101 Starter solenoid
Fuse FMX/JCase 20A 102 Ignition switch feed
Fuse FMX/JCase 20A 103 ABS valves
Fuse FMX/JCase 30A 105 Electric trailer brakes
Fuse FMX/JCase 30A 106 Trailer tow battery charge
Fuse FMX/JCase 30A 107 Power door locks (BSM)
Fuse FMX/JCase 30A 108 Passenger power seat
Fuse FMX/JCase 30A 109 Driver power seat, Adjustable pedals
Fuse FMX/JCase 30A 111 4×4 relays
Fuse FMX/JCase 40A 112 ABS pump power
Fuse FMX/JCase 30A 113 Wipers and washer pump
Fuse FMX/JCase 40A 114 Heated backlite, Heated mirror power
Fuse FMX/JCase 30A 116 Blower motor
Fuse FMX/JCase 30A 118 Heated seats
Circuit breaker MAXI 401 Power windows, Moonroof, Power sliding backlite
Relay R01 Starter solenoid
Relay R02 Accessory delay
Relay R03 Hi-beam headlamps
Relay R04 Heated backlite
Relay R05 Trailer tow battery charge
Relay R06 Blower motor
Relay R201 Trailer tow park lamps
Relay R202 Fog lamps
Relay R203 PCM

Key Fuses to Check for OBD2 Issues in the Passenger Compartment:

  • Fuse #41 (20A): Cigar lighter, Diagnostic connector power: This fuse directly powers the diagnostic connector, which includes your OBD2 port. If your OBD2 scanner is not powering on or connecting, this is the first fuse to inspect.
  • Fuse #5 (5A): Keep alive memory for Powertrain Control Module (PCM) and climate control module: The PCM (Powertrain Control Module) is the computer that your OBD2 scanner communicates with. A blown fuse for the PCM’s keep-alive memory could indirectly affect OBD2 communication.
  • Fuse #34 (20A): Fuel injectors and PCM power: This is another fuse related to the PCM’s power supply. Check this fuse if you suspect PCM power issues impacting OBD2.
  • Fuse #20 & #29 (15A): PCM 4×4 power: These fuses also relate to PCM power, and while primarily for 4×4 systems, PCM power issues can impact OBD2 functionality.

Auxiliary Relay Box (with DRL)

Some 2004 F-150 models are equipped with Daytime Running Lights (DRL). If your vehicle has DRL, it may have this auxiliary relay box.

Here’s the diagram for the auxiliary relay box (with DRL):

Type No. Description
Fuse ATO 5A F01 Clockspring illumination
Relay R01 4×4 CCW
Relay R02 4×4 CW
Relay R03 Daytime Running Lamps (DRL) [if equipped, otherwise not used]
Relay R201 DRL
Relay R202 A/C clutch
Diode ATO D01 A/C clutch diode

OBD2 Relevance: Fuses in this box are less likely to directly affect the OBD2 port, but it’s good to be aware of its location and functions for comprehensive electrical troubleshooting.

Auxiliary Relay Box (without DRL)

For 2004 F-150 models without Daytime Running Lights, a slightly different auxiliary relay box configuration is used.

Here’s the diagram for the auxiliary relay box (without DRL):

Type No. Description
Fuse ATO 5A F01 Clockspring illumination
Relay R01 4×4 CCW
Relay R02 4×4 CW
Relay R201 DRL
Relay R202 A/C clutch
Diode ATO D01 A/C clutch diode

OBD2 Relevance: Similar to the auxiliary relay box with DRL, this box is less likely to house the primary fuse for the OBD2 port itself, but understanding all fuse locations is part of thorough vehicle maintenance.

Conclusion

When troubleshooting OBD2 port issues on your 2004 Ford F-150, start by checking Fuse #41 (20A) “Diagnostic connector power” in the passenger compartment fuse box. If that fuse is intact, investigate the PCM-related fuses in the same box, such as #5, #34, #20, and #29, as power issues to the PCM can also prevent OBD2 communication.

By understanding the locations and diagrams of all three fuse boxes in your 2004 F-150, you can effectively diagnose and address a wide range of electrical problems, including those affecting your OBD2 port. Always refer to your vehicle’s owner’s manual for the most accurate fuse and relay information specific to your truck’s configuration.

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