Which wires give constant, ignition and ground on a 2018 Volvo VHD?
On a 2018 Volvo VHD, take constant power from the body builder connector #1 between the driver and passenger seats, pin C (wire color not published), ignition from the body builder connector #1 between the driver and passenger seats, pin D (wire color not published), and ground to clean, bare body metal. Meter every wire first.
Meter every wire before you tap it. Colors change with trim and build date.
Diagnostic port (16-pin):Driver side kick panelBest power spot:Body builder connector #1 between the seats (if equipped)System voltage:12VIgnition type:Key
Where do I get constant, ignition and ground on a 2018 Volvo VHD?
Volvo gives connections made for added equipment. It does not print a wire color for them, so go by the pin number.
Option 1 Constant, ignition and ground
Body builder connector #1
Between the driver and passenger seats (if equipped).
Constant
Color not printed
Body builder connector #1 between the driver and passenger seats, pin CFused battery power from the Body Builder maxi fuse, 25 amp max. Circuit F19A1.
Ignition
Color not printed
Body builder connector #1 between the driver and passenger seats, pin DFused ignition power from the 15 amp IGN-X fuse, draw 12 amp max. Circuit F35A1. Pins H and J are two more ignition feeds (F47A1 and F46A1).
Ground
Color not printed
Body builder connector #1 between the driver and passenger seats, pin ABody builder ground return, 30 amp max. Circuit X03DH3. Volvo says it connects to the ground stud on the firewall.
Pins and circuit numbers from Volvo's body builder instructions for the VHD. A 16-way Packard GT 280 plug on trucks built with Volvo's body builder prep kit, so a truck may not have it. Pin G is +12V in reverse (circuit F49A4, 5 amp max).
Option 2 Power and ground
Accessory plugs
Center of the dash, below the fuse and relay center.
Constant
Color not printed
Accessory plugs in the center of the dash, below the fuse and relay centerSix 2-pin plugs that Volvo provides for power and ground to added accessories. Volvo does not say which are battery and which are switched, so meter each one with the key off and on.
Ground
Ground stud
Ground stud on the firewallVolvo calls this the central ground point for body builder loads.
From a Volvo bulletin for the VNL, VNR, VNX, VAH and VHD, model year 2018 and newer. Volvo says the correct fuse for each plug is printed on a harness label by the connector.
From Volvo's body builder instructions, section 3 (editions February 2018, April 2023 and October 2024) and two Volvo bulletins filed with NHTSA. Volvo's ELD installation bulletin, written for trucks built up to September 13, 2019, says third-party devices must not be connected to the main diagnostic connector under the steering wheel.
Where are the turn signal, reverse and light wires on a 2018 Volvo VHD for advanced 360 multicam and video telematics installs?
Circuit
Wire color
Location and what it does
Left turnPositive +Not yet checked
Yellow
End of frame lighting connector, 3-way Metri-Pack 630, cavity ALeft turn signal light. The mating connectors are in the cab when the truck is delivered.
Right turnPositive +Not yet checked
Green
End of frame lighting connector, 3-way Metri-Pack 630, cavity BRight turn signal light. The mating connectors are in the cab when the truck is delivered.
Park lightPositive +Not yet checked
Brown (tail)
Black (marker and clearance)
End of frame lighting connector, 3-way Metri-Pack 480, cavities 2 and 1Trailer tail lamps are brown. Trailer marker and clearance lamps are black, so do not mistake that wire for a ground.
HeadlightNot foundNot yet checked
Not found
Not foundWe found no source for this wire.
ReversePositive +Not yet checked
Color not printed. Circuit F49A4
Body builder connector #1 between the driver and passenger seats, pin G+12V when the transmission is in reverse, 5 amp max. Only on trucks with the body builder connector.
Dome lightNot foundNot yet checked
Not found
Not foundWe found no source for this wire.
Each chip shows the main insulation color with its stripe. Source: Volvo's body builder instructions, section 3 (editions February 2018, April 2023 and October 2024) (end of frame connector tables).
Where are the brake, door, speed and CAN wires on a 2018 Volvo VHD for advanced 360 multicam and video telematics installs?
Circuit
Wire color
Location and what it does
BrakePositive +Not yet checked
Red
End of frame lighting connector, 3-way Metri-Pack 480, cavity 3Stop lights. Volvo says these circuits give separate stop and turn signals.
Auxiliary ignition powerPositive +Not yet checked
Blue
End of frame lighting connector, 3-way Metri-Pack 630, cavity CAuxiliary 12V ignition power at the end of the frame.
Ground at the end of frameNegative -Not yet checked
White
End of frame, 1-way Maxi connector, cavity AGround for the end of frame lighting circuits.
DoorsNot foundNot yet checked
Not found
Not foundWe found no source for this wire.
Parking brakeNot foundNot yet checked
Not found
Not foundWe found no source for this wire.
HazardNot foundNot yet checked
Not found
Not foundWe found no source for this wire.
Vehicle speedNot foundNot yet checked
Not found
Not foundWe found no source for this wire.
J1939 dataDataNot yet checked
Yellow
Green
Twisted pair. On Cummins trucks the 9-pin diagnostic connector has yellow at pin C and green at pin DVolvo says no connections may be made to the CAN high and CAN low wires, and they must not be cut or spliced. Volvo's manual is not consistent about which color is high, so do not go by color for polarity.
Diagnostic data linkDataNot yet checked
White with orange stripes (both wires)
ISO 14229 data link, wires DL2H and DL2LVolvo says both wires are white with orange stripes. Do not cut or splice them.
Source: Volvo's body builder instructions, section 3 (editions February 2018, April 2023 and October 2024). Headlight, door, parking brake, hazard and speed wires were not found.
Which years share wiring with the 2018 Volvo VHD?
This page2018Volvo VHD.
Same wiring2019, 2020, 2021, 2022, 2023, 2024Volvo prints the same VHD connector table in its 2018 and 2024 body builder instructions. The RP1226 connector starts with model year 2019. Trucks built on or after January 1, 2021 have a newer cab control unit.
Not this page2017 and older, and 2025 onOlder trucks use different circuit numbers. We have not confirmed 2025 and newer yet.
Where are the fuse boxes and ground points on a 2018 Volvo VHD?
InteriorFuse and relay center, center of the dashThe six accessory plugs sit just below it. We found no fuse table for these trucks, so no fuse number is given. Read the fuse legend decal in the truck.
Diagnostic connector16-pin connector, driver side kick panelVolvo prints pin 16 as battery positive, pin 4 as chassis ground, pin 5 as signal ground and pin 1 as the key switch ignition signal. Trucks with a Cummins engine also have a 9-pin connector.
Ground pointsGround stud on the firewallVolvo calls it the central ground point for the truck's electrical loads.
Locations from the Volvo body builder instructions and the Volvo accessory connection bulletin.
Where is the 16-pin diagnostic port on a 2018 Volvo VHD?
16-PIN
Diagnostic port16-pin diagnostic port: driver side kick panelVolvo says third-party devices must not be connected to the main diagnostic connector. Use the accessory connections on this page instead.
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This page covers the 2018 Volvo VHD.
Volvo prints body builder connector #1 between the seats and six accessory plugs below the fuse and relay center for added equipment, with no wire colors. The RP1226 accessory connector starts with model year 2019. The lamp wire colors on this page are from the end of frame lighting connectors. Our own team has not yet metered these on a 2018 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 2018 Volvo VHD wiring
Where is the reverse wire on a 2018 Volvo VHD?
The wire color is not published. It is at the body builder connector #1 between the driver and passenger seats, pin G. +12V when the transmission is in reverse, 5 amp max. Meter it before you tap it.
Where is the brake wire on a 2018 Volvo VHD?
Red (positive +) at the end of frame lighting connector, 3-way Metri-Pack 480, cavity 3. Stop lights. Meter it before you tap it.
Which years share wiring with the 2018 Volvo VHD?
2019, 2020, 2021, 2022, 2023, 2024. Volvo prints the same VHD connector table in its 2018 and 2024 body builder instructions.
Help build this page
Had the panels off on one of these? Show the next installer what you found.
No one has sent photos for the 2018 Volvo VHD yet, so yours could be the first. Every photo, wire color and tip we use goes on this page with your name on it, and it saves the next installer time under the dash.
1. Snap it
The plugs, tap points, fuse boxes and ground points. Phone photos are fine.
2. Send it
Tap "Add yours" at the top of this page. Your tip and your photos go in the same box.
3. See your name on it
We check every tip, then post it here "Compliments of" you, by name.
Compliments of
The installers who helped build this page.
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Founding contributor spot: openThe first installer to confirm a wire or send photos for the 2018 Volvo VHD gets their name here, and it stays here.
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Every tip we use gets a creditThe wire you checked is marked "Checked on a truck, compliments of" you.
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