Miniature Light Bulb "fun"

Joined
Apr 4, 2009
Messages
702
Location
Southeastern, PA
The original license plate bulbs in my Equinox burned out after 7 years. Pretty good lifespan! Replacing them is a 5 minute job. Actually finding the bulbs was a hassle.

GM (manual) says to use W5WLL
Philips says their equivalent part is a 12961
Wagner says their equivalent part is 17177
Sylvania shows no equivalent part in their parts finder

Pepboys sells a Champion branded 17177, but they were sold out
NAPA also sells the 17177, but they were sold out
Both Autozone and Advanced Auto said they could get the bulbs for me in 5-7 days. However they said the Sylvania 2825 was an exact equivalent (despite Sylvania's own parts finder saying they had no matching bulb for the license plate bulb.)
No one around here offers the Philips 12961.
Peak sells a 2825 bulb, but the nearest in stock source for that was 20 miles away.

Found a bulb cross reference chart online that showed GM W5WLL = 12961 = 17177 = 2825

Went to Walmart who had the Sylvania 2825 in stock for $5 for two bulbs. Walmart now keeps their automotive lighting products in a locked case. Had to have the Tire Center clerk unlock the case to get the bulbs. They also require customers to pay for the bulbs at the Tire Center register. Guess they were having quite an issue with light bulb theft or something.

The Sylvania 2825 was an exact fit. Other sources online claim a 194 bulb will also work. Instead of being a 5W bulb, the 194 is a 3.9W bulb so there might be a very slight brightness difference. That would have been my alternative if I couldn't find the 5W bulb.

It is interesting that there is no consistency in part numbers for these miniature light bulbs. Also not sure if the supply chain shortage was the cause of having to look all over for a pack of bulbs, or because they last so long they aren't sold with enough frequency for the auto parts stores to keep in regular inventory. Who knows. I didn't bother calling a GM dealer. GM's retail price per bulb is $5...double the price of aftermarket.
 

ryster

Thread starter
Joined
Apr 4, 2009
Messages
702
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Southeastern, PA
Those bulbs probably cost you $20 each factoring in the time it took to find them.:unsure:

No kidding. The funny thing is I went to Sylvania's website first to get their equivalent bulb. The only reason I went down the "rabbit hole" was because their site indicated no matches. Had their system shown the 2825 as being an exact match, I would have just gone to Walmart to begin with and been all set.

Incidentally, I just checked their site again just now and it shows the 2825 as an exact fit. The site must have been down when I actually needed it. Too funny!
 

ryster

Thread starter
Joined
Apr 4, 2009
Messages
702
Location
Southeastern, PA
Sylvania 2825 and 194 are the same bulbs, both 5W.

Just different packages.

194 is 3.8W, 2825 is 5W
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Joined
Apr 26, 2005
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Under the hood
W5W is a bulb type, or category, an international standard defined by UN Regulation 37 for automotive filament bulbs, which most of the world follows, with the notable outliers being the U.S. and Canada.

A W5W is a W5W, whether it comes from Osram/Sylvania (2825), Philips (12961), or whomever. If consistency is the goal, go by the bulb type, not the part number, or the trade number. European cars will specify bulb applications by those standard designations, not the numbers.

For everyone else, it's murkier, especially when there are other bulbs which may share the same physical form factors, and bases, making them physically interchangeable, but may differ in output, life, or electrical characteristics, even if only slightly.

It's kind of a wild west in that respect, and for those who don't pay attention to detail, or particularly care, it may not matter, since the square peg fits into the square opening, and it lights up. Good enough for most.

But, as a practical matter, there can be pitfalls, when something like a bulb failure detection circuit expects a certain current value, and because it doesn't read what is expected, triggers a false positive failure light, which is even more fun when it happens intermittently. I've seen this happen on a Volvo.

Another example -- it's not uncommon for BMW owners to casually substitute an 1156 for the proper P21W. Two problems with that -- an 1156 draws more current than a P21W (27W vs 21W), and isn't required to have a nickel-plated base to guard against corrosion. That leads to melted, or corroded contacts in the bulb fixtures, an issue often seen on BMW forums. An 1156 ≠ P21W.

Unfortunately, application guides contain errors, and lazy manufacturers use liberal interchange guidelines because they don't truly produce a specific type of bulb.

Substitutions sometimes work, other times they don't. The smart move, as any experienced finicky Euro car owner knows, is to play by the book, or risk paying the consequences, quite literally. That extends to simple things like bulbs as well.
 
Joined
Jun 15, 2003
Messages
38,107
Location
ME
I went through this with my saturns, they changed the spec from 3057 to 3157 tail light bulbs at one point. I think the legal standard for light emission changed and this is how they met it.

I honestly would have taken the bulb, recognized the base, and thrown a 194/168 in it out of my junk drawer. Probably an LED version to boot... less heat, longer life, more white light which would look good on a license plate.
 
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