F-250, F-350 and F-450 pickups and F-350 to F-550 chassis cabs. Gas and 6.4L diesel. First year of this generation.
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Which wires give constant, ignition and ground on a 2008 Ford Super Duty?
On a 2008 Ford Super Duty, take constant power from the Blue/Red wire at the ignition switch, gray 10-pin plug, pin 8 and ignition from the White/Orange wire at the ignition switch, gray 10-pin plug, pin 1, and ground to clean, bare body metal. Meter every wire first.
Written by API Signal, fleet GPS and camera installers for 35+ years across Georgia, South Carolina and North Carolina, installing every major telematics and camera brand. Every wire on this page lists its source.
Test every wire with a meter before you tap it
No wiring information is ever guaranteed. Colors and locations change with trim, options and build date, and the manufacturer can change them in the middle of a model year. We share this as a starting point for installers, and you are responsible for confirming every connection on the truck in front of you.
This page covers the 2008 Ford Super Duty, the first year of the generation that ran through 2010. It covers the F-250, F-350 and F-450 pickups and the F-350 to F-550 chassis cabs, with the 5.4L V8, the 6.8L V10 or the new 6.4L Power Stroke diesel. Every truck has a regular key, and the ignition switch plug on the steering column is the easiest power spot.
The full wire table comes from a 2010 truck, and an installer's 2008 F-250 post matches it on every power wire. The upfitter switch colors come from Ford's own 2008 bulletin. Our own team has not yet metered these on a 2008 truck, and each row says so.
OBD-II portUnder the driver dash
Best power spotIgnition switch plug
System voltage12V (diesel: 2 batteries)
Ignition typeKey only
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Where do I get constant, ignition and ground on a 2008 Ford Super Duty?
Take constant, ignition and ground from the same area. On this truck the ignition switch plug on the steering column has constant, ignition, accessory and start in one spot.
Option 1 Easiest
At the ignition switch
Steering column, gray 10-pin plug. Remove the lower column shroud. Every 2008 to 2010 Super Duty has a regular key.
Constant
Blue/Red
Ignition switch, gray 10-pin plug, pin 8Always hot, 20A. Pin 9 is a second constant; one table lists it Blue/Red, another White/Violet, so meter it.
Ignition
White/Orange
Ignition switch, gray 10-pin plug, pin 1Hot in run and start
Ground
Body ground
No ground at the switchUse clean, bare body metal under the driver dash. Never the battery negative post.
Accessory
Brown/Yellow
Ignition switch, gray 10-pin plug, pin 7Hot in accessory and run. Violet/Green on pin 5 is a second accessory wire.
Start
Blue/White
Ignition switch, gray 10-pin plug, pin 10Hot only while cranking
Key sense is Blue/Gray (+) on pin 3. The switch is fed from fuse 27 (20A), which also feeds other circuits, so keep the device draw small.
Option 2 Fuse tap
At the passenger fuse panel
Smart junction box in the passenger footwell, behind a pull-off cover.
Constant
Not found
No battery-hot fuse confirmedWe did not find a published always-hot fuse slot for this panel. Meter a slot with the key off before using a fuse tap.
Ignition
Fuse tap
Fuse 44 (10A), passenger fuse panelFord's owner's guide calls it the run customer access feed (PTO). Meant for upfitters. Use an add-a-fuse tap.
Ground
Body ground
Body metal in the passenger kick areaClean, bare metal only.
We did not find wire colors for power at the junction box itself. Use this only when the steering column is hard to reach.
Switch pins from an aftermarket install table for a 2010 F-350 (Directed, reposted on the12volt), re-checked at the source. An installer's 2008 F-250 post has the same colors on every power wire. Fuse 44 from Ford's owner's guides for 2008, 2009 and 2010.
What are the turn signal, reverse and light wires on a 2008 Ford Super Duty?
Circuit
Wire color
Location and what it does
Left turnPositive +Not yet checked
Blue/Green (front)
Gray/Brown (rear)
Smart junction box, passenger kick: black 26-pin plug F, pin 21 front; black 32-pin plug D, pin 25 rearFlashes with the left signal. Blue/Green is also the lock wire on another plug, so go by plug and pin.
Right turnPositive +Not yet checked
Yellow/Violet (front)
Violet/Orange (rear)
Junction box: plug F, pin 23 front; plug D, pin 26 rearFlashes with the right signal. Yellow/Violet is also the unlock wire on another plug. We did not confirm whether the rear bulb is combined stop and turn.
Park lightPositive +Not yet checked
Violet/White
Junction box, gray 13-pin plug E, pin 6On with the park lights. The switch side is Gray (-) at the headlight switch, gray 10-pin plug, pin 3.
HeadlightNegative -Not yet checked
Yellow/Blue
Headlight switch, left of the steering wheel, gray 10-pin plug, pin 8Switch input, grounds with the headlights on
ReversePositive +Not yet checked
Green/Brown
Reverse relay in the under-hood fuse box, black 59-pin plug, pin 41Hot in reverse. The pin number showed up in only one of two reads of the source, so meter it.
Dome lightPositive +Not yet checked
Yellow/Gray
Junction box, gray 14-pin plug A, pin 9Dome lamp output
Each chip shows the main insulation color with its stripe. Source: Directed install table for a 2010 F-350, carried to 2008 because the install guides treat 2008 to 2010 as one platform.
Where are the brake, door, speed and CAN wires on a 2008 Ford Super Duty?
Circuit
Wire color
Location and what it does
BrakePositive +Not yet checked
Violet/White
Brake pedal switch, or junction box black 52-pin plug B, pin 40Hot with the pedal pressed. Same color as the park light output, so confirm by location. Ford warns that splicing into the stop lamp switch can damage the body module; use it as a sense input only.
Driver doorNegative -Not yet checked
Green/Violet
Junction box, gray 26-pin plug C, pin 14Door open input. A 2008 installer post says Blue under the driver seat; the 2010 table is more detailed, so we show it first. Meter it.
Passenger doorNegative -Not yet checked
White
Junction box plug C, pin 2Door open input
Rear doorsNegative -Not yet checked
Green (left rear)
Yellow (right rear)
Junction box plug C, pin 3 left, pin 15 rightSuperCab and Crew Cab only
Parking brakeNegative -Not yet checked
White/Violet
Junction box plug C, pin 1Grounds with the parking brake set
HazardNegative -Not yet checked
Brown/Yellow
Junction box black 52-pin plug B, pin 48Hazard switch input. Brown/Yellow is also the accessory wire at the ignition switch.
Vehicle speedAC signalNot yet checked
Violet/Orange
Customer access harness behind the OBD portSpeed signal. Violet/Orange is also medium-speed CAN low at the OBD port, so go by location.
TachAC signalNot yet checked
Blue
Customer access harness behind the OBD portEngine speed. A 2008 installer found it as a loose Blue wire in the driver kick panel.
Upfitter switchesPositive +Not yet checked
Yellow (Aux 1, 30A)
Green/Brown (Aux 2, 30A)
Violet/Green (Aux 3, 10A)
Brown (Aux 4, 15A)
Blunt-cut wires under the dash, left of the steering column, near the relay pack. Remove the trim cover below the column.Trucks with the factory upfitter switches only (option 66S). Hot only in run, through relays. Colors from Ford's 2008 upfitter switch bulletin.
CAN busDataNot yet checked
White/Blue (HS high)
White (HS low)
OBD port, black 16-pin, pin 6 high, pin 14 lowFor CAN-clip installs. Never cut or splice it. Medium-speed CAN is Gray/Orange (pin 3) and Violet/Orange (pin 11).
Sources: the Directed install table for a 2010 F-350 (reposted on the12volt), an installer's 2008 F-250 post on the12volt, Ford's 2008 upfitter switch bulletin (Q-117-R1), Ford's 2008 to 2010 owner's guides (fuses), and a Blue Oval Trucks article on the upfitter wires. Park/neutral, PTO status, 4x4 status, high beam and third brake light were not found.
Which years share wiring with the 2008 Ford Super Duty?
This page2008, first year of this generationPickups and chassis cabs. Ford's 2008 upfitter bulletin covers every F-250 to F-550.
Same wiring2009 and 2010iDatalink treats 2008 to 2010 Super Duty trucks as one platform, one remote start harness fits all three years, and Ford's owner's guides use the same ignition, upfitter and trailer brake fuse numbers for all three. The full wire table is from a 2010 truck; a 2008 installer post matches it on every power wire.
Not this page2007 and older, 2011 and newer2007 is the older generation. For 2011 Ford renumbered the fuses, the upfitter switches started working in accessory too, and the 6.7L diesel arrived. Those years get their own pages.
Where are the fuse boxes and ground points on a 2008 Ford Super Duty?
InteriorPassenger fuse panelSmart junction box in the passenger footwell, behind a pull-off cover. Fuse 27 (20A) feeds the ignition switch. Fuse 44 (10A) is the run customer access feed. Fuse 33 (10A) is the trailer brake controller. Fuses 14 (10A) and 16 (15A) feed upfitter switches 3 and 4. Relay 48 is delayed accessory.
Under the hoodPower distribution boxEngine compartment. Fuses 7 and 8 (30A) feed upfitter switches 1 and 2, and fuse 5 (30A) the trailer brake controller. A fuse-diagram site (lower trust) puts the reverse relay at 19.
Ground pointsClean body metalWe did not find a published ground point for this truck. Use clean, bare body metal under the dash, never the battery negative post. Diesels have two batteries.
Fuse numbers from Ford's 2008 owner's guide. Our team has not yet checked them on a truck.
Where is the OBD-II port on a 2008 Ford Super Duty?
OBD II
Diagnostic portOBD-II port: under the driver dashPlug-in GPS trackers and OBD harnesses connect here. Check the port before you plan the install.
Common questions about 2008 Ford Super Duty wiring
What wire is constant power on a 2008 Ford Super Duty?
Blue/Red at the ignition switch, gray 10-pin plug, pin 8. Always hot, 20A. Meter it before you tap it.
What wire is ignition on a 2008 Ford Super Duty?
White/Orange at the ignition switch, gray 10-pin plug, pin 1. Hot in run and start. Meter it before you tap it.
Where is the reverse wire on a 2008 Ford Super Duty?
Green/Brown (positive +) at the reverse relay in the under-hood fuse box, black 59-pin plug, pin 41. Hot in reverse. Meter it before you tap it.
Where is the brake wire on a 2008 Ford Super Duty?
Violet/White (positive +) at the brake pedal switch, or junction box black 52-pin plug B, pin 40. Hot with the pedal pressed. Meter it before you tap it.
Where is the parking brake wire on a 2008 Ford Super Duty?
White/Violet (negative -) at the junction box plug C, pin 1. Grounds with the parking brake set. Meter it before you tap it.
Where is the vehicle speed signal on a 2008 Ford Super Duty?
Violet/Orange at the customer access harness behind the OBD port. Speed signal. Meter it before you tap it.
Which years share wiring with the 2008 Ford Super Duty?
2009 and 2010. iDatalink treats 2008 to 2010 Super Duty trucks as one platform, one remote start harness fits all three years, and Ford's owner's guides use the same ignition, upfitter and trailer brake fuse numbers for all three.
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