Is your Super Duty cranking but not starting, stalling at random, or showing low fuel pressure? A common cause on 2002, 2003, 2004, 2005, 2006 and 2007 F-250, F-350, F-450, and F-550 trucks is a failing fuel pump relay inside the Central Junction Box, also called the interior fuse box or CJB. The relay is soldered to the circuit board, not a plug-in relay. We repair the root cause and upgrade the relay for long-term reliability.
What the Central Junction Box Does
The CJB distributes power to critical systems and houses multiple relays for body and engine functions. On these model years it sits under the driver side dash, below and to the left of the steering column behind a small panel.
Why These Fuse Boxes Fail
Inside the CJB there are two printed circuit boards linked by a dense row of interconnect pins. The fuel pump relay is soldered to one of these boards. Years of heat, vibration, and current load can weaken the relay or its solder joints, which leads to intermittent power to the fuel pump.
Symptoms We Fix
- Crank no start with no fuel pump prime
- Random stalling while driving
- Intermittent or weak fuel pump operation
- Low fuel pressure complaints
- Trouble code P0231 or similar low circuit voltage faults
Our Repair Method
Refer to the photo below for how the boards are built. To do this job correctly, the two boards must be separated without damaging the copper pads or traces. Here is how we handle it:
- We carefully desolder every interconnect pin so the boards can be opened cleanly.
- We replace the fuel pump relay with a better than OEM part rated for heat and vibration.
- We inspect and reflow any stressed solder joints, then resolder all interconnect pins.
- We bench test pump control and power feeds before return shipping.
Many companies and DIY attempts skip the desoldering step and simply cut the pins, then try to solder them back together. That shortcut creates weak joints that crack again with vibration and can cause more problems later. Our method preserves the board, restores reliability, and prevents repeat failures.
What You Get From CBoardRepair
- Board-level relay replacement with premium components
- Proper desoldering and reassembly of the two-board CJB
- Reinforcement of known weak points
- Full bench testing for fuel pump relay control and output
- 24 hour turnaround after your fuse box arrives
- Lifetime warranty on the faults we repair
Compatibility
- 02-07 Ford F-250
- 02-07 Ford F-350
- 02-07 Ford F-450
- 02-07 Ford F-550
Engines: Power Stroke 7.3L and 6.0L, Triton 6.8L V10, Triton 5.4L V8
Easy 3-Step Process
Step 1: Select and buy the repair service you need
Order here: https://cboardrepair.com/products/2002-2007-ford-super-duty-f250-f350-f450-f550-fuse-box-cjb-repair
Step 2: Safely remove the faulty part from your vehicle
Include a note with your
- Order Number
- Contact details (phone and email)
- Return address
- A brief description of the problem.
Step 3: Ship your part to us
CBoardRepair
517 Quanah Parker Road
Rogersville, MO 65742
We repair your item as soon as it arrives and aim to have it back on its way to you within 24 hours.
Repair Versus Replacement
- Repair keeps your original unit and vehicle configuration.
- Used fuse boxes are a gamble because many have the same aging relay.
- New fuse boxes are discontinued
- Our repair installs a stronger relay and restores the board connections for lasting reliability.
FAQs
Where is the interior fuse box located?
Below and to the left of the steering column behind the panel near the brake pedal.
Will I need programming after reinstall?
No. This is your original fuse box. Reinstall and go.
How long does the repair take?
We target a 24 hour turnaround from the moment your part arrives.
What does the lifetime warranty cover?
The internal faults we repair on the CJB for as long as you own the vehicle. It does not cover water damage, impact damage, or tampering.
Ready To Fix Your Super Duty
Order your repair, send in your Central Junction Box, and get your truck back to reliable starting and smooth driving with a lifetime-backed repair.
