DRL bulb replacement?

tech49

2019 2500 144 4cyl GAS
I cant believe I have to ask this, but coming up nil in all searches and cant find a match on amazon. Both DRL bulbs are dead and labelled with Toshiba 12v21w - nothing close matches on amazon. ANyone know what bulbs and where to get them?
 

autostaretx

Erratic Member
The Owner's manual (page 101 or so in the 2015) calls the DRL bulb a "W21W"

Doing a google search on "W21W equivalent" comes up with a number of contenders:
https://www.svetila.com/en/car-bulb...-7505-w3x16d-original-line-4008321090652.html
this
https://www.walmart.com/ip/Sylvania-7440-Long-Life-Miniature-Bulb-Contains-2-Bulbs/54633831
and this
https://www.amazon.com/Auxbeam-Light-Bulbs-Reverse-signals/dp/B07414XVKT (LED)

the "21W" in the number says "21 watts" ... the W21W probably means "wire base" (i.e. bent wires on the glass tab)

You might drop in at an auto parts store and stare at the wall of blister packed bulbs...

--dick
 

tech49

2019 2500 144 4cyl GAS
The walmart link looks like a good match, both in specs and appearance. thx

I didnt check the manual bc its usually no help at all...
 

rollerbearing

Well-known member
Careful on that Sylvania 7440. It says it's 25 W. Not saying that it has or that it will, but my experience with Toyota and Mercedes bulb receptacles is that they sometimes melt if you put in the ever so slightly higher wattage. Maybe better safe than sorry. If is supposed to be a 21W, I would try real hard to stick to 21W.
 

rollerbearing

Well-known member
Although when I look at the amazon photos of the above bulb it says 12V 21W on the glass envelope.

Could be that it's 13.5V 25Watts (per package) and 12V 21W (per label on glass). Then I'd guess you may just be OK.
 

autostaretx

Erratic Member
25 w/13.5v = 1.85 amps
13.5 v/1.85 amp = 7.3 ohms
12v / 7.3 ohms = 1.64 amps
1.64 amp * 12v =19.73 watts

Yeah, close enough to 21 watts...

--dick (bulbs are not "ideal devices", their resistance changes a bit depending upon temperature)
((yes, i could'a used W=V^2/R or W=R*I^2, but i felt like walking it through))
 

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