Difficulty

Moderate

Steps

15

Time Required

                          4 hours

Sections

1

  • How to Repair a 2010-2014 Ford Mustang Smart Junction Box
  • 15 steps

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Introduction

What you need

Step 1

              How to Repair a 2010-2014 Ford Mustang Smart Junction Box
  • Pull hood release tab inside the car.
  • After this step, protective gloves should be worn.

Pull hood release tab inside the car.

After this step, protective gloves should be worn.

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Step 2

  • Disconnect the positive side battery cable from the battery with an 8mm wrench.
  • Place the positive side battery cable on a non-conductive surface, like a towel.
  • Electric shock can occur if positive side of battery is grounded

Disconnect the positive side battery cable from the battery with an 8mm wrench.

Place the positive side battery cable on a non-conductive surface, like a towel.

Electric shock can occur if positive side of battery is grounded

Step 3

  • Pull off the passenger side kick-plate panel by pulling on the unconnected end with moderate force.
  • The kick-plate panel is located under the glove compartment and beside the passenger door.

Pull off the passenger side kick-plate panel by pulling on the unconnected end with moderate force.

The kick-plate panel is located under the glove compartment and beside the passenger door.

Step 4

  • Remove the six connectors from the junction box. The large connector at the bottom of the junction box will be removed during step 6.
  • Be careful not to break any plastic tabs or clips.

Remove the six connectors from the junction box. The large connector at the bottom of the junction box will be removed during step 6.

Be careful not to break any plastic tabs or clips.

Step 5

  • Unhook nearby wires from hangers on junction box by using a flat head screwdriver.
  • Use the screwdriver to push on the hanger tab and then pull the wire connector forward.

Unhook nearby wires from hangers on junction box by using a flat head screwdriver.

Use the screwdriver to push on the hanger tab and then pull the wire connector forward.

Step 6

  • Using a 10 mm socket wrench, remove the mounting nut from bottom of junction box.
  • Slightly lift the junction box and then remove the final large connector on the bottom of the junction box.
  • Lift the junction box 90 degrees to unhook the junction box from the fender wall and then pull the junction box completely out.

Using a 10 mm socket wrench, remove the mounting nut from bottom of junction box.

Slightly lift the junction box and then remove the final large connector on the bottom of the junction box.

Lift the junction box 90 degrees to unhook the junction box from the fender wall and then pull the junction box completely out.

Step 7

  • Inspect all connectors for corrosion to indicate where the junction box needs cleaning.

Inspect all connectors for corrosion to indicate where the junction box needs cleaning.

Step 8

  • Place the junction box in a clean ventilated area and on a flat surface.
  • Remove the fuse panel cover.

Place the junction box in a clean ventilated area and on a flat surface.

Remove the fuse panel cover.

Step 9

  • Using the fuse puller located in the fuse cover, remove all of the small fuses.
  • Remove the larger fuse and relay by hand using moderate force.
  • Take a picture of fuses before removing to record their locations.

Using the fuse puller located in the fuse cover, remove all of the small fuses.

Remove the larger fuse and relay by hand using moderate force.

Take a picture of fuses before removing to record their locations.

Step 10

  • Use a flat head screwdriver or plastic opening tool to detach the small tabs on the junction box.
  • The small tab locations are circled in red.
  • To prevent damage to the walls of the junction box, do not widen the side of the junction box too far.

Use a flat head screwdriver or plastic opening tool to detach the small tabs on the junction box.

The small tab locations are circled in red.

To prevent damage to the walls of the junction box, do not widen the side of the junction box too far.

Step 11

  • Remove the top plastic cover and the control boards from the bottom cover.
  • As you lift the top of the junction box, ensure the control boards do not fall out.
  • Static shock can damage the components on the control boards. Discharge static build up by touching a large metal object before touching the control boards.

Remove the top plastic cover and the control boards from the bottom cover.

As you lift the top of the junction box, ensure the control boards do not fall out.

Static shock can damage the components on the control boards. Discharge static build up by touching a large metal object before touching the control boards.

Step 12

  • Examine the top junction box cover for any corrosion or burn spots.
  • You can identify corrosion by a green, yellow or blue substance.
  • You can identify burn spots by melted plastic and/or black spots.

Examine the top junction box cover for any corrosion or burn spots.

You can identify corrosion by a green, yellow or blue substance.

You can identify burn spots by melted plastic and/or black spots.

Step 13

  • If no burns are found, spray contact cleaner on corroded areas. If there are burns on the control board, the junction box can not be saved.
  • Avoid too much overspray on adjacent components of control boards.
  • Safety glasses should be worn to prevent cleaner from splashing in your eyes.
  • You must be in a well ventilated area.

If no burns are found, spray contact cleaner on corroded areas. If there are burns on the control board, the junction box can not be saved.

Avoid too much overspray on adjacent components of control boards.

Safety glasses should be worn to prevent cleaner from splashing in your eyes.

You must be in a well ventilated area.

Step 14

  • Before the contact cleaner dries, scrub the corroded components on the control board with a tooth brush.
  • Scrub the control board cover with a wire or soft brush as needed.
  • Do not use wire brush on the control board. The wire brush could potentially bend pins and damage components.

Before the contact cleaner dries, scrub the corroded components on the control board with a tooth brush.

Scrub the control board cover with a wire or soft brush as needed.

Do not use wire brush on the control board. The wire brush could potentially bend pins and damage components.

Step 15

  • Spray a moderate amount of contact cleaner on all corroded wire connectors.
  • Make sure connectors that were connected to corroded areas on the junction box are cleaned even if there is no indication of corrosion.
  • Before the contact cleaner dries, use a wire brush or soft brush to clean off the corrosion.
  • On hard plastic connectors, there is no risk from damage by a wire brush.
  • Allow all components to dry for three or more hours.

Spray a moderate amount of contact cleaner on all corroded wire connectors.

Make sure connectors that were connected to corroded areas on the junction box are cleaned even if there is no indication of corrosion.

Before the contact cleaner dries, use a wire brush or soft brush to clean off the corrosion.

On hard plastic connectors, there is no risk from damage by a wire brush.

Allow all components to dry for three or more hours.

To reassemble your device, follow these instructions in reverse order.

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                    Bret James

Member since: 06/19/2019

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                                            1 Guide authored

Steve Sibo - Jan 25, 2022

Reply

Great job with this guide.

rizzle razzleuno - Apr 7, 2022

Reply

Fantastic, with good photos. My 2011 Mustang Tire Pressure Monitor system is putting up error message “Tire Pressure Sensor Fault” but the sending units in the wheels/tires are new and have been tested twice as working correctly and the TPMS system was reset, but after 30 minutes of driving the warning light flashes and the error message appears. Tire pressure is exactly what it is supposed to be. I asked the local Ford dealer what they charged to determine what is wrong with the system…….$200!.. No thanks. Then I found out the Smart Junction Box (AKA Body Control Module) is $432 from this dealer, but can be had new from other Ford dealers for as low as $290. However I strongly suspect that the only problem is a bad electrical connection, so I will follow this guide to clean the contacts and I bet that is the cure. I will post an update after I clean the contacts and verify there are no signs of overheating or failed components and if the problem is fixed.

djani jose - May 16, 2022

did you try the fix?

Ronald Powell - Sep 4, 2022

Reply

My 2012 mustang GT 5.0 just went dead battery good lights still come on but once I turn the key forward no lights on the dash window don’t go up I’m Definitely about to go outside side and try this what I have to lose thank you I will up date late