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Which wires give constant, ignition and ground on a 2008 Chevrolet Silverado 1500 / GMC Sierra 1500?
On a 2008 Chevrolet Silverado 1500 / GMC Sierra 1500, take constant power from the Red/White wire at the BCM, under the dash left of the steering column, black plug, pins 1 to 4 and ignition from the Pink wire at the BCM light green plug, pin 14, 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 Chevrolet Silverado 1500 and GMC Sierra 1500 in the GMT900 body. The Silverado and Sierra share the same wiring. The easiest power spot is the body control module under the dash, left of the steering column, with constant, ignition and accessory together.
The colors come from a 2013 wire table and match an installer's 2008 Avalanche table, which is the same platform. 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 spotBCM, left of the column
System voltage12V
Ignition typeKey
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Where do I get constant, ignition and ground on a 2008 Chevrolet Silverado 1500 / GMC Sierra 1500?
Take constant, ignition and ground from the same area. On this truck the body control module (BCM) under the dash, left of the steering column, has constant, ignition and accessory within a few inches.
Option 1 Easiest
At the BCM
Body control module, under the driver side of the dash, left of the steering column. Remove the lower dash panel.
Constant
Red/White
BCM, under the dash left of the steering column, black plug, pins 1 to 4Always hot, four 15A feeds. Use one pin. Pin numbers come from a 2013 truck; colors match on the 2008 sources we found.
Ignition
Pink
BCM light green plug, pin 14Hot in run and start. 2007, 2009, 2012 and 2013 sources agree on the color.
Ground
Body ground
Body metal under the driver dashClean, bare metal only. Never the battery negative post.
Accessory
Brown
BCM light green plug, pin 21Hot in accessory and run. The 2013 sheet says Brown or Yellow; 2008 and 2009 sources say Brown.
The main dash fuse box also has two Red/Black 60A constant feeds on its black 40-pin plug (pins E3 and F1). Use those only with an inline fuse.
Option 2 Ignition switch
At the ignition switch
Steering column. The switch uses resistor-coded start and accessory signals, so it is best for ignition sense only.
Constant
Not for power
Do not use the switch constantThe Red/White wire at the ignition switch only carries about 2A. Take constant from the BCM (Option 1).
Ignition
Pink
Ignition switch harness, steering columnHot in run and start. Same Pink wire as at the BCM.
Ground
Body ground
Body metal under the driver dashClean, bare metal only.
Accessory
Brown
Ignition switch harnessHot in accessory and run.
Key sense is Pink/Black. The start circuit uses a resistor code on a White wire, and the sources disagree on the values, so do not tap it.
Power wires from an installer-reported wire table for a 2013 Silverado 1500 on the12volt (fetched three times, matched), with 2007, 2009 and 2012 installer and Audiovox sheets agreeing on the colors.
What are the turn signal, reverse and light wires on a 2008 Chevrolet Silverado 1500 / GMC Sierra 1500?
Circuit
Wire color
Location and what it does
Left turnPositive +Not yet checked
Light Blue/White (front)
Yellow (rear)
BCM brown plug, pin 4 front, pin 1 rearFlashes with the left signal. GM's 2011 upfitter manual also shows Yellow for left rear stop and turn. Pin numbers come from a 2013 truck; colors match on the 2008 sources we found.
Right turnPositive +Not yet checked
Dark Blue/White (front)
Dark Green (rear)
BCM black plug, pin 5 front; brown plug, pin 2 rearFlashes with the right signal. GM's 2011 upfitter manual also shows Dark Green for right rear stop and turn. Pin numbers come from a 2013 truck; colors match on the 2008 sources we found.
Park lightNegative -Not yet checked
Light Blue
Headlight switch, or BCM white plug, pin 8Switch input, grounds with the park lights on. The park lamp outputs are Brown (+) at the underhood fuse box, black 30-pin plug, pins A7 and F7. Pin numbers come from a 2013 truck; colors match on the 2008 sources we found.
HeadlightNegative -Not yet checked
White
BCM white plug, pin 12Headlight switch input. Pin numbers come from a 2013 truck; colors match on the 2008 sources we found.
ReversePositive +Not yet checked
Dark Blue
BCM brown plug, pin 7 or 11Hot in reverse. The 2012 and 2013 sheets agree on the color but not the pin. GM's 2011 upfitter manual lists Light Green at the rear lamp junction block, a different point on the circuit, so meter it. Pin numbers come from a 2013 truck; colors match on the 2008 sources we found.
Dome lightPositive +Not yet checked
Gray
BCM white plug, pin 5Dome lamp output. The cargo lamp is White/Black on the pink plug, pin 2. Pin numbers come from a 2013 truck; colors match on the 2008 sources we found.
Each chip shows the main insulation color with its stripe. Source: 2013 installer wire table, with colors matched on 2008-era sources.
Where are the brake, door, speed and CAN wires on a 2008 Chevrolet Silverado 1500 / GMC Sierra 1500?
Circuit
Wire color
Location and what it does
BrakePositive +Not yet checked
Light Blue/White
BCM brown plug, pin 6, or the brake switch above the pedalHot with the pedal pressed, with the ignition on. Same color as the left front turn, so go by plug and pin. Pin numbers come from a 2013 truck; colors match on the 2008 sources we found.
Driver doorNegative -Not yet checked
Gray/Black
BCM pink plug, pin 10Door open input. Trucks without premium door modules; on others the latch wires are at the door modules. Pin numbers come from a 2013 truck; colors match on the 2008 sources we found.
Passenger doorNegative -Not yet checked
Tan/White
BCM pink plug, pin 8Door open input, same note as the driver door. Pin numbers come from a 2013 truck; colors match on the 2008 sources we found.
Rear doorsNegative -Not yet checked
Light Blue/Black (left rear)
Light Green/Black (right rear)
BCM pink plug, pin 15 left, pin 14 rightCrew and Extended Cab only. Pin numbers come from a 2013 truck; colors match on the 2008 sources we found.
Parking brakeNegative -Not yet checked
Light Blue
BCM brown plug, pin 16Grounds with the parking brake set. Same color as the park light input, so go by plug and pin. Pin numbers come from a 2013 truck; colors match on the 2008 sources we found.
HazardNegative -Not yet checked
White
BCM light green plug, pin 19Hazard switch input. Pin numbers come from a 2013 truck; colors match on the 2008 sources we found.
Vehicle speedAC signalNot yet checked
Yellow/Black (ECM)
Dark Green/White (radio)
Engine computer at the driver fender; or radio brown 16-pin plug, pin 5 on some modelsThe 2008 and 2012 sources give Yellow/Black at the ECM; the 2013 sheet gives Dark Green/White at the radio. Meter both.
TachNegative -Not yet checked
White
Ignition coilInstaller-reported on 2009 and 2012 trucks. The 2013 sheet says to use any non-Pink injector wire instead. Meter it.
CAN busDataNot yet checked
Tan/Black (HS high)
Tan (HS low)
Dark Green (GMLAN)
OBD port under the driver dash, pin 6 and pin 14; single-wire GMLAN on pin 1High-speed CAN and GM single-wire CAN. Never cut or splice them.
Sources: installer-reported wire tables on the12volt for 2013, 2009 and 2007 Silverados and a 2008 Avalanche, an Audiovox sheet for a 2012 Sierra, and GM's 2011 light-duty pickup upfitter manual (rear lamp colors, upfitter connector). Park/neutral, third brake light and the full ignition switch pinout were not found.
Which years share wiring with the 2008 Chevrolet Silverado 1500 / GMC Sierra 1500?
This page2008A 2008 Avalanche table (same platform) matches on the power, park and door wires.
Same wiring2007, 2009, 2010, 2011, 2012 and 2013Installer and Audiovox sheets from 2007, 2008 (Avalanche, same platform), 2009, 2012 and 2013 trucks agree on the ignition, accessory, park, brake, reverse and door colors, and GM's 2011 upfitter manual covers Silverado and Sierra together. The only year change we found is a fuse label.
Not this page2007 Classic and 2014 and newerThe 2007 Classic is the older body with different wiring. 2014 brought a new generation. Those get their own pages.
Where are the fuse boxes and ground points on a 2008 Chevrolet Silverado 1500 / GMC Sierra 1500?
InteriorDash fuse boxesMain box at the driver end of the dash, second block under the dash left of the column. Fuse 12 is stop lamps and third brake light, 15 the BCM, 16 power outlets, 17 interior lamps. Fuse 9 is Universal Home Remote on this year.
Under the hoodUnderhood fuse boxFuse 15 backup lamps, 26 and 27 park lamps, 35 key ignition and theft, 37 and 52 upfitter battery feeds, 43 misc ignition, 49 third brake light, and the run/crank relay.
Ground pointsClean body metalWe did not find a published ground point list. Use clean, bare body metal under the dash, never the battery negative post.
Fuse numbers from a fuse-diagram site (lower trust) that lists 2007 to 2013 together. Our team has not yet checked them on a truck.
Where is the OBD-II port on a 2008 Chevrolet Silverado 1500 / GMC Sierra 1500?
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 Chevrolet Silverado 1500 / GMC Sierra 1500 wiring
What wire is constant power on a 2008 Chevrolet Silverado 1500 / GMC Sierra 1500?
Red/White at the BCM, under the dash left of the steering column, black plug, pins 1 to 4. Always hot, four 15A feeds. Meter it before you tap it.
What wire is ignition on a 2008 Chevrolet Silverado 1500 / GMC Sierra 1500?
Pink at the BCM light green plug, pin 14. Hot in run and start. Meter it before you tap it.
Where is the reverse wire on a 2008 Chevrolet Silverado 1500 / GMC Sierra 1500?
Dark Blue (positive +) at the BCM brown plug, pin 7 or 11. Hot in reverse. Meter it before you tap it.
Where is the brake wire on a 2008 Chevrolet Silverado 1500 / GMC Sierra 1500?
Light Blue/White (positive +) at the BCM brown plug, pin 6, or the brake switch above the pedal. Hot with the pedal pressed, with the ignition on. Meter it before you tap it.
Where is the parking brake wire on a 2008 Chevrolet Silverado 1500 / GMC Sierra 1500?
Light Blue (negative -) at the BCM brown plug, pin 16. Grounds with the parking brake set. Meter it before you tap it.
Where is the vehicle speed signal on a 2008 Chevrolet Silverado 1500 / GMC Sierra 1500?
Yellow/Black (ECM) and Dark Green/White (radio) at the engine computer at the driver fender; or radio brown 16-pin plug, pin 5 on some models. The 2008 and 2012 sources give Yellow/Black at the ECM; the 2013 sheet gives Dark Green/White at the radio. Meter it before you tap it.
Which years share wiring with the 2008 Chevrolet Silverado 1500 / GMC Sierra 1500?
2007, 2009, 2010, 2011, 2012 and 2013. Installer and Audiovox sheets from 2007, 2008 (Avalanche, same platform), 2009, 2012 and 2013 trucks agree on the ignition, accessory, park, brake, reverse and door colors, and GM's 2011 upfitter manual covers Silverado and Sierra together.
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