2008 GMC Yukon Brake Light Bulb Size (2007-2014 Chart)

The 2008 GMC Yukon uses a 3057KX bulb for the combined rear stoplamp, taillamp and rear turn signal, according to GM's official 2008 Yukon owner's manual. The center high-mounted stoplamp (the third brake light above the rear glass) has no bulb number in the manual's replacement table, so treat it as a dealer-serviced assembly rather than a bulb swap.

The same generation of Yukon (GMT900, 2007-2014 model years) did not keep one bulb number throughout. The early trucks list a 3057-type bulb, while later owner's manuals list a 7443. Check the chart below against your model year before you buy.

Yukon Brake Light Bulb Chart (GMT900, 2007-2014)

The numbers below come straight from the "Replacement Bulbs" tables in GM's owner's manuals for each year. Only years we could open and read are filled in.

Model year	Stoplamp / taillamp / rear turn signal	Back-up lamp	License plate lamp	Third brake light (CHMSL)
2007	3057	7441	168	Not listed in manual
2008	3057KX	7441	168	Not listed in manual
2009	3057KX	7441	168	Not listed in manual
2010	Not verified, check your manual
2011	7443	7441	W5WLL	Not listed in manual
2012	Not verified, check your manual
2013	7443	7441	W5WLL	Not listed in manual
2014	Not verified, check your manual

A few points about this table:

One bulb does three jobs. On these years the stoplamp, taillamp and rear turn signal share one dual-filament bulb in each taillamp housing. If your brake light is out but the taillamp still works on the same side, the brake filament has failed, and the fix is still the same single bulb.
The 2011 and 2013 manuals change the number. Do not assume a 3057 from an earlier Yukon will fit a 2011-or-later socket. Match the number printed in your own manual or on the old bulb.
Two-mode Hybrid trucks are excluded. Both the 2008 and 2009 manuals tell Hybrid owners to use the separate Two-mode Hybrid manual for bulb information, and the 2011 and 2013 manuals say the same about the hybrid supplement.
Yukon XL and Denali: the manuals quoted above are the standard Yukon books. If you have an XL or a Denali, look up the owner's manual for that exact model and year, or confirm by VIN with a GM parts counter.

The Third Brake Light (CHMSL)

The 2008 manual describes the Center High-Mounted Stoplamp (CHMSL) as mounted above the rear glass, and warns owners not to block or damage it when loading the roof rack. None of the 2007-2013 manuals we checked give a bulb number for it; each replacement table ends with "for replacement bulbs not listed here, contact your dealer."

In practice that means:

If the third brake light is dark but both lower brake lights work, check its fuse first. The 2008 manual lists a dedicated CHMSL fuse (No. 49) in the underhood fuse block, on the driver side of the engine compartment.
If the fuse is good, the problem is usually in the lamp unit or its wiring at the top of the liftgate. Replacement is typically done as a whole assembly; confirm the part by VIN with a dealer or parts supplier.

If both the lower brake lights and the third brake light are out at the same time, bulbs are unlikely to be the cause. Look at the brake light switch and the stoplamp circuit instead. Our GMC brake light switch replacement guide covers that side of the system, and can one brake light affect another explains how a shared circuit can take out more than one lamp.

How to Replace the Rear Brake Light Bulb (2007-2009 Yukon)

The 2008 owner's manual gives this procedure for the stoplamp/taillamp bulb:

Open the liftgate.
Remove the two screws from the taillamp assembly.
Pull the taillamp assembly rearward until the inner pins on the assembly disengage from the vehicle.
Press the release tab (if the socket has one) and turn the bulb socket counterclockwise to remove it.
Pull the old bulb straight out of the socket.
Press the new bulb into the socket, insert the socket into the assembly and turn it clockwise until it clicks.
Reinstall the taillamp assembly, lining up the pins with the vehicle. The manual notes that if the pins are not lined up, the assembly will not seat correctly.

Test the brake lights with a helper, or by backing up to a wall or garage door at night, before you put the tools away.

LED Replacement Bulbs

Plenty of LED bulbs are sold in 3057 and 7443 sizes. Before swapping, keep in mind:

Legal output matters more than brightness claims. Stop lamps are regulated by Federal Motor Vehicle Safety Standard 108, which sets photometry and color requirements for stop lamps and high-mounted stop lamps. Choose a bulb the maker states is DOT/SAE compliant for stop and turn use, and treat "X times brighter" or lifespan figures as marketing numbers that vary by product.
Hyper-flash. LEDs draw less current than the incandescent bulb, and because the Yukon's rear turn signal shares this bulb, some vehicles flash faster than normal after an LED swap. Check the product listing for GM compatibility or a load-resistor requirement.
Color. Use a red LED behind a red lens. A white LED behind a red lens can look washed out.

Frequently Asked Questions

What bulb does a 2008 GMC Yukon use for the brake lights?

GM's 2008 Yukon owner's manual lists bulb 3057KX for the rear turn signal, taillamp and stoplamp. One dual-filament bulb per side handles all three functions. The back-up lamp uses a 7441 and the license plate lamp a 168.

Is the 2007 Yukon brake light bulb the same as the 2008?

The 2007 manual lists a 3057 for the same position and the 2008 manual lists a 3057KX. Both are 3057-type bulbs. If you are unsure, pull the old bulb and match the number printed on its base.

What size is the third brake light bulb on a GMT900 Yukon?

The owner's manuals for 2007, 2008, 2009, 2011 and 2013 do not list a bulb for the center high-mounted stoplamp. They direct owners to a dealer for any bulb not in the table. Check the CHMSL fuse first, then replace the lamp assembly if the fuse is good.

Do 2011-2014 Yukons use the same brake light bulb?

Not the same as the earlier trucks. The 2011 and 2013 owner's manuals list a 7443 for the stoplamp, taillamp and rear turn signal. We could not confirm 2010, 2012 or 2014, so check your own manual or the old bulb for those years.

Why is only my third brake light out on my Yukon?

Because the CHMSL has its own fuse (No. 49 in the 2008 underhood fuse block), a blown fuse can kill it while the lower lamps keep working. If the fuse is good, the fault is usually in the lamp unit or its wiring at the liftgate.