Severe duty vocational truck. 9-pin diagnostic port.
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Which wires give constant, ignition and ground on a 2016 Freightliner 108SD and 114SD?
On a 2016 Freightliner 108SD and 114SD, take ignition from the Pink wire at the ignition splice pack, circuit 81C, below the radio, at the center back wall of the dash, and ground to the Black wire at the ground splice pack, below the radio, at the center back wall of the dash. 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 2016 Freightliner 108SD and 114SD, a year with two data bus layouts.
These trucks are multiplexed: the ignition switch only signals a control module, so there are no ignition switch wires to tap. Freightliner provides splice packs below the radio for ignition and ground, and those are the wires on this page. Trucks built before January 1, 2016 still have J1708. Trucks built on or after that date do not, and they have two J1939 buses. Check the build date on the door label. Our own team has not yet metered these on a 2016 truck.
9-pin diagnostic portUnder the dash on the driver side, outboard of the steering column
Best power spotIgnition and ground splice packs below the radio
System voltage12V
Ignition typeIgnition switch
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Where do I get constant, ignition and ground on a 2016 Freightliner 108SD and 114SD?
Freightliner gives a tap point for ignition and ground behind the dash. It does not print a constant wire at that spot.
Option 1 Ignition and ground
Dash splice packs
Below the radio. Freightliner's own tap point for added equipment.
Constant
Not published
Not found at this spotFreightliner prints no constant wire at the splice packs. Use option 2.
Ignition
Pink
Ignition splice pack, circuit 81C, below the radio, at the center back wall of the dashFreightliner's tap point for key-on power. 5 amps maximum. Live while cranking. Not live in the accessory position.
Ground
Black
Ground splice pack, below the radio, at the center back wall of the dashFreightliner's ground tap point. 10 amps maximum.
Ignition and ground from Freightliner's 2015 body builder electrical guide and Freightliner bulletin 54-267, which covers trucks built before and after January 1, 2016. Any open cavity in the splice pack can be used.
Option 2 Constant
Freightliner constant power
Front wall power box or a spare fuse in the main fuse box.
Constant
Fuse C, color not published
Power box on the front wall, next to the bulkhead module: cavity 3, fed by fuse CFreightliner takes constant power here for its own telematics unit and runs the wire through an open cavity of the dash side bulkhead connector. This fuse is a keep-alive feed.
Constant
Spare fuse, color not published
Main fuse box under the hood, spare fuse positions F25 and F26The 2015 guide marks these two as hot at all times. Spare positions change with the options on the truck, so check the fuse label on the truck.
From Freightliner. The front wall power box was added for 2010. Its keep-alive fuses stay live with the battery disconnect switch off. The rest of the truck does not, so a device fed from anywhere else goes dead when the driver turns that switch off.
This truck is multiplexed. The ignition switch only signals the bulkhead module and is not a power feed, and no source gives its wire colors.
What are the turn signal, reverse and light wires on a 2016 Freightliner 108SD and 114SD?
Circuit
Wire color
Location and what it does
Left turnPositive +Not yet checked
Yellow (separate turn lamp)
Red/White (combined stop and turn)
Rear light connector: pin F on trucks with separate turn lamps (circuit 38L), pin C on trucks with combined stop and turn (circuit 39L). Also chassis module plug C1, pin G (separate) or pin N (combined)Left rear turn lamp output.
Right turnPositive +Not yet checked
Dark Green (separate turn lamp)
Red/White (combined stop and turn)
Rear light connector: pin C on trucks with separate turn lamps (circuit 38R), pin D on trucks with combined stop and turn (circuit 39R). Also chassis module plug C1, pin P (separate) or pin L (combined)Right rear turn lamp output.
Park lightPositive +Not yet checked
Brown
Rear light connector, pin B, circuit 23. Also chassis module plug C1, pins D and ETaillights and license light.
HeadlightNot foundNot yet checked
Not found
Bulkhead module plug B1, pin R (left low beam). Pin onlyFreightliner prints the pin but no wire color.
ReversePositive +Not yet checked
Dark Blue
Rear light connector, pin A, circuit 120B. Also chassis module plug C1, pins A and JBackup lamp output.
Dome lightNot foundNot yet checked
Not found
Bulkhead module plug B5, pin B (dome lamps switched). Pin onlyFreightliner prints the pin but no wire color.
Each chip shows the main insulation color with its stripe. Source: Freightliner's 2015 body builder electrical guide (rear light connector and chassis module tables).
Where are the brake, door, speed and CAN wires on a 2016 Freightliner 108SD and 114SD?
Circuit
Wire color
Location and what it does
BrakePositive +Not yet checked
Red/White
Rear light connector: left stop lamp circuit 39L, right stop lamp circuit 39R (pins G and D with separate turn lamps, pins C and D with combined stop and turn). Also chassis module plug C1, pins N and LStop lamp outputs. On combined trucks these wires also flash with the turn signal. The brake switch itself is an input on chassis module plug C3, pin G, and its color is not printed.
DoorsPolarity: meter itNot yet checked
Not found
Bulkhead module plug B6: pin A7 driver door, pin A6 passenger door. Pins onlyFreightliner prints the pins but no wire color or polarity.
Parking brakeNegative -Not yet checked
Not found
Chassis module plug C3, pin F. Pin onlyFreightliner lists this input as active low. No wire color is printed.
HazardNot foundNot yet checked
Not found
Bulkhead module plug B6, pin B8 (hazard switch input). Pin onlyFreightliner prints the pin but no wire color.
Body builder battery feedPositive +Not yet checked
Red
Optional body builder connector at the back of the cab or the end of the frame, circuit 14UBattery power, fused. Only on trucks ordered with a body builder or customer access connector.
Body builder ignition feedPositive +Not yet checked
Pink
Same optional connector, circuit 52FIgnition power through a relay. Only on trucks ordered with the option.
Dash illuminationPositive +Not yet checked
Brown
Illumination splice pack, circuit 29A, below the radio, at the center back wall of the dashLive with the panel lamps. 5 amps maximum.
Vehicle speedNot foundNot yet checked
Not found
Not foundWe found no source for this wire.
J1939 dataDataNot yet checked
Yellow (+)
Green (-)
Built before January 1, 2016: J1939 connection at the top center of the dash. Built on or after that date: any of the three dash splice packs (driver side, center, passenger side)Twisted pair, 250K. On trucks built January 1, 2016 and later this is the bus Freightliner tells added devices to use, and J1708 is gone. The White/Yellow and White/Green pair is the 500K vehicle bus: leave it alone.
Sources: Freightliner's 2015 body builder electrical guide, Freightliner bulletin 54-267 and other Freightliner bulletins. Port location is from the 2015 guide, and some trucks were ordered with the 9-pin port in the center of the dash. Door, parking brake, hazard, headlight and dome circuits are printed as module pins without colors. Vehicle speed and the 9-pin port pin assignments were not found.
Which years share wiring with the 2016 Freightliner 108SD and 114SD?
This page2016108SD and 114SD.
Same wiringDepends on the build dateBuilt before January 1, 2016: same as 2015. Built on or after that date: same data bus layout as 2017. The ignition and ground splice packs are the same either way.
Not this page108SD Plus, 114SD Plus and the 122SDThe Plus trucks, about 2024 on, have a new electrical system. The 122SD is not named in these Freightliner documents. Neither is covered.
Where are the fuse boxes and ground points on a 2016 Freightliner 108SD and 114SD?
InteriorOptional fuse and relay box behind the driver seatTrucks ordered with body builder or trailer options have it behind the driver seat on day cabs, or under the rear bench on crew cabs. No other cab fuse panel is described in the Freightliner documents we read.
Under the hoodMain fuse box (power distribution module)A second power box with the keep-alive fuses is on the front wall next to the bulkhead module.
Ground pointsGround splice pack below the radioFreightliner also names frame ground studs near the chassis module.
Locations from Freightliner's 2015 body builder guide and bulletin 54-267. Fuse positions change with the options on the truck, so go by the fuse label on the truck.
Where is the 9-pin diagnostic port on a 2016 Freightliner 108SD and 114SD?
9-PIN
Diagnostic port9-pin diagnostic port: under the dash on the driver side, outboard of the steering columnPlug-in GPS trackers and J1939 devices connect here.
Common questions about 2016 Freightliner 108SD and 114SD wiring
What wire is ignition on a 2016 Freightliner 108SD and 114SD?
Pink at the ignition splice pack, circuit 81C, below the radio, at the center back wall of the dash. Freightliner's tap point for key-on power. Meter it before you tap it.
Where is the reverse wire on a 2016 Freightliner 108SD and 114SD?
Dark Blue (positive +) at the rear light connector, pin A, circuit 120B. Also chassis module plug C1, pins A and J. Backup lamp output. Meter it before you tap it.
Where is the brake wire on a 2016 Freightliner 108SD and 114SD?
Red/White (positive +) at the rear light connector: left stop lamp circuit 39L, right stop lamp circuit 39R (pins G and D with separate turn lamps, pins C and D with combined stop and turn). Also chassis module plug C1, pins N and L. Stop lamp outputs. Meter it before you tap it.
Where is the parking brake wire on a 2016 Freightliner 108SD and 114SD?
The wire color is not published. It is at the chassis module plug C3, pin F. Pin only. Freightliner lists this input as active low. Meter it before you tap it.
Which years share wiring with the 2016 Freightliner 108SD and 114SD?
Depends on the build date. Built before January 1, 2016: same as 2015.
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