Smart junction box

It is a known issue

https://www.google.com/search?q=2005+Ford+Freestar+Van+%2F+with+power+door+locks.+Smart+Junction+Box

..

test brake light switch

Have you checked fuse's an relay's ? Free wiring diagrams here http://www.bbbind.com/free-tsb Enter vehicle info. Year , make , model . Under system click on body & accessories , then under subsystem click on power locks or windows .Click the search button then the blue link . At the top of the diagram it shows fuse's that power these thing's . Check those first . Do you know how to test automotive electrical circuit's using a voltmeter ? Do you know what a ford smart junction box is ? The SJB is a fuse / relay panel that has electronic's inside . It is located inside the car under dash panel ,left side .

Module Controlled Functions The vehicle is equipped with a smart junction box (SJB) and a driver seat module.
Smart Junction Box (SJB)
The SJB is a combined fuse panel and microprocessor that controls the following systems:

• interior lighting
• exterior lighting
• horn
• heated rear window
• delayed accessory
• power door locks (including SMART, autolocking and luggage compartment lid release)
• remote keyless entry (RKE)
• perimeter anti-theft
• battery saver relay

I can give you a pdf of the owners manual which will show the Location of what you call the junction box which is under the hood. It is called the "Power Distribution Box" It is on page 235 of the manual. http://www.fordservicecontent.com/Ford_Content/catalog/owner_guides/05winog3e.pdf

What do you want to know ? Automatic smart junction box ? It's called just SJB - smart junction box !

Sorry but it is non - serviceable , location smart junction box ! If the relay were bad you would need to replace the smart junction box . Is the air bag light lit ! ( possible clock spring )
Inspection and Verification

1. Verify the customer concern.

1. Visually inspect the following for obvious signs of mechanical or electrical damage.

Visual Inspection Chart Mechanical Electrical

• Horn
• Horn switch (part of the steering wheel)

• Battery junction box (BJB) fuse 2 (50A)
• Smart junction box (SJB) fuse 14 (20A)
• Circuitry
• Clockspring
• BJB
• SJB

Symptom Chart Condition Possible Sources Action

• The horn is inoperative

• Fuse
• Circuitry
• Steering wheel switch harness
• Horn
• Clockspring
• Horn switch (part of the steering wheel)
• Smart junction box (SJB)

• Go To Pinpoint Test A .

Symptom Chart Condition Possible Sources Action

• No communication with the smart junction box (SJB) module

• Circuitry
• Smart junction box (SJB)

• REFER to Section 418-00 .

• All power windows are inoperative

• Circuitry
• Window control switch
• Circuit breaker
• Smart junction box (SJB)
• Delayed accessory relay

• Go To Pinpoint Test A .

It is located in the SJB smart junction box , it's a fuse / relay center / microprocessor ! Fuse # F2.10 30 amp . location -behind left side dash panel . Also check the accessory relay . Top relay left side , same location SJB .
Visual Inspection Chart Mechanical Electrical

• Door window regulator and motor
• Door glass top run
• Door window glass

• Loose, corroded connectors
• Circuitry
• Window control switch
• Battery junction box (BJB) fuse(s):
  • 1 (60A)
  • 3 (60A)
  • 11 (50A)
• Smart junction box (SJB) fuse(s):
  • 7 (20A)
  • 27 (10A)
  • 30 (10A)
• SJB circuit breaker 10 (30A)
• SJB rear window defrost relay 1
• Relay center box 1 rear window defrost relay 2
• Delayed accessory relay
• Battery saver relay
• Rear window defrost grid

The first thing to check is the tail lights. The cruise control will not work if any lights are out. Changing to LED tail lights also causes the cruise to not work.

Is the air bag light lit on the instrument cluster ? The horn relay isn't under the hood in the engine compartment , it's in the SJB - smart junction box located inside the passager compartment . Under the dash panel left side . You can take the relay back to autozone because it's not the right one ! The relay is inside the smart junction box ,soldered to the printed circuit board !
Horn Horn
The vehicle is equipped with dual horns. The horns are mounted in the LF frame rail corner behind the front bumper.
The horn system consists of the following components:

• steering wheel horn switches
• clockspring
• horns
• smart junction box (SJB)

Horn Switch, Steering Wheel Mounted
The horn switches are incorporated within the driver side air bag module in the steering wheel. The switches are grounded and control the horns through the clockspring. For removal and installation of the driver side air bag module, refer to Section 501-20B .
Visual Inspection Chart Mechanical Electrical

• Horn
• Horn switch

• Battery junction box (BJB) fuse 1 (60A)
• Smart junction box (SJB) fuse 38 (15A).
• Circuitry
• Speed control actuator
• Clockspring
• SJB

Smart Junction Box (SJB) Diagnostic Trouble Code (DTC) Index
DTC Description Source Action B1217 Horn relay coil circuit failure Smart junction box (SJB) If the horn is inoperative, Go To Pinpoint Test A . If horns sound continuously, Go To Pinpoint Test B . B1218 Horn relay coil circuit short to battery Smart junction box (SJB) Go To Pinpoint Test A .
Any codes ?
Symptom Chart NOTE: Refer to Wiring Diagrams for connector numbers stated in the pinpoint test. Condition Possible Sources Action

• The horn is inoperative

• Battery junction box (BJB) fuse 1 (60A).
• Smart junction box (SJB) fuse 38 (15A).
• Circuitry.
• SJB.
• Horn switch.
• Horn.
• Speed control actuator.

• Go To Pinpoint Test A .

Your best bet , take it to a qualified ford service center .