Heavy duty tractor. Key start. 16-pin diagnostic port.
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Which wires give constant, ignition and ground on a 2018 Volvo VNL and VNR?
On a 2018 Volvo VNL and VNR, take constant power from the accessory plugs in the center of the dash, below the fuse and relay center (wire color not published), 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 2018 Volvo VNL and VNR.
Volvo gives six accessory plugs below the fuse and relay center for added equipment, with no wire colors printed. 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.
Diagnostic port (16-pin)Driver side kick panel
Best power spotAccessory plugs below the fuse and relay center
System voltage12V
Ignition typeKey
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Where do I get constant, ignition and ground on a 2018 Volvo VNL and VNR?
Volvo gives the accessory plugs below the fuse and relay center for added equipment. It does not print a wire color for them.
Option 1 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 plugs 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. Each accessory plug also has its own ground cavity.
From a Volvo bulletin for the VNL, VNR, VNX, VAH and VHD, model year 2018 and newer. The plug is a Delphi 2-pin 280 series Metri-Pack. Volvo says the correct fuse for each plug is printed on a harness label by the connector.
Option 2 Data and power
Volvo overlay harness
Dealer part that adds an RP1226 plug.
Data and power
Pins not printed
Volvo overlay harness, part 23295912A Volvo bulletin for trucks built up to September 13, 2019 says this harness connects to the truck and ends in an RP1226 plug for a telematics device. We could not read its pins.
From Volvo's ELD installation bulletin. The RP1226 connector itself is fitted from model year 2019.
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.
What are the turn signal, reverse and light wires on a 2018 Volvo VNL and VNR?
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.
ReverseNot foundNot yet checked
Not found
Not foundWe found no source for this wire.
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 VNL and VNR?
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). Reverse, door, parking brake, hazard and speed wires were not found.
Which years share wiring with the 2018 Volvo VNL and VNR?
This page2018VNL and VNR.
Same wiring2019, 2020, 2021, 2022, 2023, 2024Volvo prints the same tables in its 2018, 2023 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 the all-new VNL (model year 2025 on)Older trucks use different circuit numbers. The all-new VNL has a different electrical system and we found no wire colors for it.
Where are the fuse boxes and ground points on a 2018 Volvo VNL and VNR?
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 VNL and VNR?
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.
Common questions about 2018 Volvo VNL and VNR wiring
Where is the brake wire on a 2018 Volvo VNL and VNR?
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 VNL and VNR?
2019, 2020, 2021, 2022, 2023, 2024. Volvo prints the same tables in its 2018, 2023 and 2024 body builder instructions.
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