Which wires give constant, ignition and ground on a 2026 Chevrolet Low Cab Forward 6500XD?
On a 2026 Chevrolet Low Cab Forward 6500XD, take constant power from the Red wire at the rear manufacture connector J-118, rear of the frame near the rear lamps, pin B, ignition from the Green/Orange wire at the power source plug B-220, center of the dash, right side of the cab fuse/relay center, pin 1, and ground to the Black/Blue wire at the rear manufacture connector J-118, rear of the frame near the rear lamps, pin D. Meter every wire first.
Meter every wire before you tap it. Colors change with trim and build date.
OBD-II port:Under the dash, driver sideIgnition plug:B-220, center dashSystem voltage:12VEngine:Diesel
Where do I get constant, ignition and ground on a 2026 Chevrolet Low Cab Forward 6500XD?
GM gives the 2026 6500XD a key-on power plug in the dash and a 4-pin body builder plug at the back of the frame.
Option 1 Ignition
Power source plug B-220
White 1-pin plug in the center of the dash, right side of the cab fuse and relay center.
Ignition
Green/Orange
Power source plug B-220, center of the dash, right side of the cab fuse/relay center, pin 1Ignition voltage from fuse A-3.
Constant
Fuse tap
Use Option 2 or a fuse tapGM prints no battery wire in the cab for this truck.
Ground
Bare metal
Clean bare cab metalGM prints no cab ground color.
Best ignition sense in the cab.
Option 2 Battery at the rear
Rear manufacture plug J-118
Blue 4-pin plug at the rear of the frame.
Constant
Red
Rear manufacture connector J-118, rear of the frame near the rear lamps, pin BBattery voltage from fuse F36.
Ground
Black/Blue
Rear manufacture connector J-118, rear of the frame near the rear lamps, pin DGround to J-298.
Marker
Light Green/Black
Rear manufacture connector J-118, rear of the frame near the rear lamps, pin AMarker lamp relay output.
Pin C (White/Black) is the rear dome lamp output.
All colors from GM's 2026 Chevrolet Low Cab Forward body builder electrical guide (6500XD section), printed as text in its connector tables.
Where are the turn signal, reverse and light wires on a 2026 Chevrolet Low Cab Forward 6500XD for advanced 360 multicam and video telematics installs?
Circuit
Wire color
Location and what it does
Left turnNot foundNot yet checked
Not found
Not foundNot printed in GM's 2026 guide. See our 2018 6500XD page for that year's colors.
Right turnNot foundNot yet checked
Not found
Not foundNot printed in GM's 2026 guide.
Park lightPositive +Not yet checked
Light Green/Black
Rear manufacture connector J-118, rear of the frame near the rear lamps, pin AMarker lamp relay output, on with the lamps.
HeadlightNot foundNot yet checked
Not found
Not foundNot printed in GM's 2026 guide.
ReversePositive +Not yet checked
Red/Blue
Back-up lamp and alarm connector J-111, left rear frame rail behind the axle, pin 1Voltage from fuse A-4, only in reverse.
BrakeNot foundNot yet checked
Not found
Not foundNot printed in GM's 2026 guide.
Each chip shows the main insulation color with its stripe. Source: GM's 2026 Chevrolet Low Cab Forward body builder electrical guide (6500XD section).
Where are the brake, door, speed and CAN wires on a 2026 Chevrolet Low Cab Forward 6500XD for advanced 360 multicam and video telematics installs?
Circuit
Wire color
Location and what it does
Rear battery feedPositive +Not yet checked
Red
Rear manufacture connector J-118, rear of the frame near the rear lamps, pin BBattery voltage from fuse F36.
Rear dome outputPositive +Not yet checked
White/Black
Rear manufacture connector J-118, rear of the frame near the rear lamps, pin CRear dome lamp switched output.
Rear groundNegative -Not yet checked
Black/Blue
Back-up lamp and alarm connector J-111, left rear frame rail behind the axle, pin 2Ground. Also Black/Blue at J-118 pin D.
PTO switchPolarity: meter itNot yet checked
White
Body builder connector H-246, left inner frame rail next to the fuel tank, pin 8PTO switch to the transmission control module.
Auto neutralPolarity: meter itNot yet checked
Pink
Body builder connector H-246, left inner frame rail next to the fuel tank, pin 9Auto neutral to the transmission control module.
DoorsNot foundNot yet checked
Not found
Not foundNot printed in GM's guide.
Vehicle speedNot foundNot yet checked
Not found
Not foundNot printed in GM's guide.
Source: GM's 2026 Chevrolet Low Cab Forward body builder electrical guide (6500XD section). Turn, stop, headlight, door and speed wires are not printed there.
Where are the fuse boxes and ground points on a 2026 Chevrolet Low Cab Forward 6500XD?
Ground pointsJ-298, J-9, J-7Frame grounds for the rear plugs. In the cab, use clean bare metal, never the battery negative post.
From GM's 2026 Chevrolet Low Cab Forward body builder electrical guide (6500XD section). Our team has not yet checked these on a truck.
Where is the OBD-II port on a 2026 Chevrolet Low Cab Forward 6500XD?
OBD II
Diagnostic portOBD-II port: under the dash, driver sidePlug-in GPS trackers and OBD harnesses connect here. Check the port before you plan the install.
Which years share wiring with the 2026 Chevrolet Low Cab Forward 6500XD?
This page2026Chevrolet LCF 6500XD.
Earlier2018 6500XDDifferent manual with full ignition switch pinout.
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This page covers the 2026 Chevrolet Low Cab Forward 6500XD, the Class 6 diesel cab-over built with Isuzu.
Every color here comes from GM's own 2026 body builder guide. Our own team has not yet metered these on a 2026 truck.
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.
Common questions about 2026 Chevrolet Low Cab Forward 6500XD wiring
What wire is constant power on a 2026 Chevrolet Low Cab Forward 6500XD?
Red at the rear manufacture connector J-118, rear of the frame near the rear lamps, pin B. Battery voltage from fuse F36. Meter it before you tap it.
What wire is ignition on a 2026 Chevrolet Low Cab Forward 6500XD?
Green/Orange at the power source plug B-220, center of the dash, right side of the cab fuse/relay center, pin 1. Ignition voltage from fuse A-3. Meter it before you tap it.
Where is the reverse wire on a 2026 Chevrolet Low Cab Forward 6500XD?
Red/Blue (positive +) at the back-up lamp and alarm connector J-111, left rear frame rail behind the axle, pin 1. Voltage from fuse A-4, only in reverse. Meter it before you tap it.
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The plugs, tap points, fuse boxes and ground points. Phone photos are fine.
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Tap "Add yours" at the top of this page. Your tip and your photos go in the same box.
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