Here are the most common bulbs you’ll need to replace besides headlights and the number they’re sold under (Osram, Sylvania, Eiko, etc.). The ECE designation is often found stamped on the socket, reflector, lens and sometimes the bulb. Do NOT use 1156, 1157, 194, 67, or other “U.S.” bulbs (see LONG VERSION and section 5. for details). Only use bulbs with CLEAR, tint-free glass with the exception of amber-colored bulbs used with clear lenses (versus clear bulbs with amber lenses).
If you don't see a picture table following this, log in or click here for a preview. NOTE: W1.2W is technically not an ECE designation, but it is commonly referred to as such and follows the same format. The R10W (5008) bulb has been largely phased out of use as a tail light in favor of the R5W (5007) as the greater shift in intensity between tail and brake intensity better communicates “BRAKE” to following motorists. The 1.2W SV5.5 bulb for the vanity mirror is a non-standard special order bulb.
|1.||Commonly Confused Bulbs|
|2.||Confusion Examples and Avoidance|
|A. Volvo Part Numbers|
|B. Neo-Wedge Bulbs|
|C. Festoon Bulbs|
|D. Side Mirror “Approach” Bulbs|
|E. 3000-Series Bulbs|
1. Commonly Confused Bulbs
are no more identical than
tires that fit the same wheel
-- specs can and do vary.
A few examples of bulbs many claim are “the same” but are not, hence manufacturers treating them as different products.
|ECE||Osram #||Base||Glass||Volts||Watts||Amps||Lumens||Base Plating|
|P21W||7506||BA15s||S8||12 V||21 W||1.75 A||460 lm||Nickel|
|-||1156||BA15s||S8||12.8 V||26.9 W||2.1 A||402 lm||Brass|
|W3W||2821||W2.1x9.5d||T3-1/4||12 V||3 W||0.25 A||22 lm||n/a|
|-||194||W2.1x9.5d||T3-1/4||14 V||3.78 W||0.27 A||25 lm||n/a|
|R5W||5007||BA15s||B6||12 V||5 W||0.42 A||50 lm||Nickel|
|-||67||BA15s||G6||13.5 V||8 W||0.59 A||50 lm||Brass|
2. Confusion Examples and Avoidance
The point here is to highlight the need for correct information by how easily confusion happens and proliferates, and how to avoid repeating them. Hey, we’re all human, right?
Owners can get confused... like the differences between 194 versus W3W (2821) bulbs, realizing to get the same wattage, mixing up base names and interchangeability, or mixing SAE with ECE bulbs.
Bulb companies can get confused... such as Sylvania recommending a 1156 bulb for 1998 Volvo S70’s "Center High Mount Stop Light”... which is LED. Same page also recommends the 5-watt 2827 bulb for the "Front Turn Signal.” For the most part, they just republish info and don’t check the 1,000s of models across dozens of manufacturers going back for decades.
Vendors can get confused... such as picturing a dual-filament bulb (P21/5W) for "Volvo Tail Light Reverse Bulb 5W - Genuine 989788" but tail lights (5W, RED lens) and reverse lights (21W, CLEAR lens) can NOT share the same light source. Worse, "Volvo Fog Light Bulb - Osram 64152" and "Volvo Fog Light Bulb - Osram 64153" are 100W bulbs and should NOT be used in place of the OEM 55W bulbs without upgrading the wiring and components (read why in 5. Common Questions).
And even Volvo gets confused! One can go to Volvo’s Owners Manual site to look up what bulbs your car uses, BUT even those have some glaring mistakes. Some are obvious like swapping the text "1.2 W SV 5.5" festoon text for the picture of the "5W W2.1x9.5d" wedge bulb, and vice versa. Sometimes it's the sidebar, like this 2003 V70 listing "21/4W, BA 15 s" instead of BAZ15d ("d" is for the double contacts for the dual filaments: 21W and 4W). For a 2007, they skip ahead a couple world conflicts and list "WW5, SV8.5." While there is no "WW5" bulb, there is a W5W but it has a W2.1x9.5d wedge base, not a SV8.5 festoon one. The one for a 2005 S40 has multiple typos like “P21/W5” instead of P21/5W, but even P21/5W is wrong because that's a dual-contact bulb so #4 should be P21W, #6 R5W, and #7 should be C5W. Neither the description, specification, nor picture match in some cases! At least this one for a 2005 S80 is pretty good. So if you’ve found bulb selection confusing, take heart as you’ve got company.
Volvo’s way versus the right way. (More in “6. Tips!”) Avoiding Confusion The EASIEST way to avoid using the wrong bulb is to simply inspect where it goes. European vehicles like Volvo are apt to have a ECE designation like R5W, P21W or C5W stamped, printed or cast somewhere on the socket, reflector or lens. Hey, ya' gotta go there to get to the bulb in the first place, right? Take note of the depth and location of where the bulb’s pins hook into the socket (compare red and green dots). Use the same base as BA15s, BA15d, BAY15d, BAU15d, and BAZ15d are each different with good reason and just some of the dozens. Use the same wattage, which is a measure of power used, NOT light produced. However, since Volts x Amps = Watts, you also want to use the same voltage. While 6 V and 24 V are clearly wrong, others are rated at 12, 12.8, 13.5, 14, and ever 14.4 volts and under- OR over-volting a bulb effects both performance and longevity. The history and rationale are mixed, but choice for testing can be: 12 via standard and nominal (ECE; “12-volt system”), 12.8 via battery (6 cells at ~2.1 V each; SAE), ~14.4 via maximum regulated alternator output, 14 via radio or rounded alternator, and 13.5 averaged (battery + alternator / 2). Use the same amperage, as amps are what your wires or fuses are designed to handle or fail at respectively. Lumens, light output, is what most are concerned about, but the voltage a bulb is tested or rated at will affect both it power used (watts) and light given off (lumens). Glass shape and gas type (e.g. halogen, xenon, krypton, ...) also have an effect, the latter often producing much more heat and ultra-violet radiation which can melt and break down plastics in the socket, wiring, reflector and lens over time.
Source: http://sylvaniaautomotivecatalog.wbdev. ... ilamps.gif
Definition: MSCD, Mean Spherical Candela, nearly the same as MSCP (Mean Spherical Candlepower)
If that seems a lot to check, it is, which is why the simplest is to just stick with the ECE bulbs listed here and pictured under the “SHORT VERSION” above as well as making sure both sides are running the same bulb.
|W1.2W *||2721||dash indicators|
|R10W *||5008 *||tail|
|P21W||7506||brake, turn reverse, or fog|
|P21/4W||7225||tail (4W) and brake or fog (21W)|
|P21/5W||7528||tail (5W) and brake or fog (21W)|
3. COMPARISON TABLES
A. Volvo Part Numbers Use <ctrl+F> to Find your bulb number faster.
Different numbers for the same bulb are included on the right to avoid redundant entries.
FIVE- and SIX-DIGIT Volvo BULBS (most common)
|19917||12 V||5 W||W2.1x9.5d||-||-||-||X5W (Xenon W5W)|
|19926||24 V||5 W||SV8.5-8||C5W||6423||45 lm||41x11mm|
|182026||24 V||15 W||BA15s||-||7529||-||-|
|182032||24 V||45/50 W||BA20d||-||7359||-||-|
|182034||24 V||2 W||BA9s||-||3797||-||-|
|182040||24 V||10 W||SV8.5-8||-||6429||-||41x11mm|
|182046||12 V||15 W||SV8.5-8||-||6451||-||41x15mm|
|182059||24 V||3 W||BA7s||-||3899||-||-|
|190591||12 V||25 W||BA15s||-||7582||-||-|
|192091||12 V||6 W||BA9s||-||6253||-||-|
|192105||24 V||18 W||SV8.5-8||-||6480||-||41x15mm|
|192200||12 V||18 W||BA15s||-||7527||-||-|
|192455||12 V||45/40 W||P45t-41||R2||7951||860/675 lm||-|
|277808||24 V||10 W||BA15s||R10W||5637||125 lm||-|
|942086||24 V||55/50 W||P45t-41||R2||7952||1000/860 lm||-|
|942310||12 V||18 W||SV8.5-8||-||6475||-||41x15mm|
|942327||12 V||1.2 W||W2x4.6d||W1.2W||2721||6.4 lm||-|
|943498||24 V||5 W||BA15s||R5W||5627||50 lm||-|
|943904||24 V||70 W||P14.5s||H1||64155||1900 lm||-|
|945091||24 V||21 W||BA15s||P21W||7511||460 lm||-|
|963187||12 V||60/55 W||P43t-38||HB2||9003||1590/980 lm||DOT version of H4|
|964763||24 V||75/70 W||P43t||H4||64196||1900/1200 lm||-|
|965826||12 V||21 W||BA15s||P21W||7506||460 lm||-|
|965827||12 V||21 W||BA15s||P21W||7506||460 lm||-|
|965831||12 V||5 W||SV7||-||DE3022||38 lm||-|
|966326||12 V||1.2 W||B8.5d||-||2721MF||6.4 lm||-|
|967711||24 V||4 W||BA9s||T4W||3930||35 lm||& 182025|
|977302||12 V||60/55 W||P43t||H4||64193||1650/1000 lm||& 963187 (DOT)|
|977709||12 V||1.2 W||W2x4.6d||W1.2W||2721||6.4 lm||-|
|977710||12 V||21/4 W||BAZ15d||P21/4W||7225||440/15 lm||-|
|981815||12 V||1 W||-||-||-||-||Window switch bulb|
|982558||24 V||21 W||BAU15s||PY21W||665201*||-||*Flosser|
|983581||85 V||35 W||P32d-2||D2S||66240||3200 lm||Xenon HID|
|983609||12 V||51 W||P22d (180°)||HB4A||9006XS||1095 lm||“55W”|
|987790||12.8 V||11 W||W2.1x9.5d||“W11W”||912||151 lm||see “Side Mirror Light”|
|987896||12 V||35 W||PGJ19-1||H8||64212||800 lm||-|
|989750||12 V||65 W||PGJ19-5||H9||64213||2100 lm||-|
|989755||12 V||15 W||BA15s||-||7533||210 lm||& 11489|
|989756||12 V||21 W||BA15s||P21W||7506||460 lm||-|
|989757||12 V||21 W||BA15s||P21W||7506||460 lm||long life|
|989758||12 V||27 W||BA15s||(SAE)||1156||402 lm||-|
|989759||24 V||25 W||BA15s||-||7597||430 lm||-|
|989760||12 V||5 W||BA15s||R5W||5007||50 lm||-|
|989761||12 V||10 W||BA15s||R10W||5008||125 lm||-|
|989762||13.5 V||5 W||BA15s||R5W||5007||50 lm||& 946777, 965828|
|989763||13.5 V||7 W||BA15s||(SAE)||67||50 lm||& 965829|
|989764||24 V||10 W||BA15s||R10W||5637||125 lm||-|
|989765||12 V||2 W||BA9s||(DIN)||3796||12.5 lm||& 182055|
|989766||12 V||3 W||BA9s||-||3894||28 lm||-|
|989767||12 V||4 W||BA9s||T4W||3893||35 lm||& 965830|
|989768||12 V||5 W||BA9s||-||3860||50 lm||21.5mm|
|989769||24 V||2 W||BA9s||(DIN)||3797||17.5 lm||-|
|989772||12 V||2 W||BA7s||-||3898||9.4 lm||& 19923, Eiko (A)1272|
|989773||12 V||10 W||SV8.5-8||(DIN)||6411||100 lm||& 12795071, DE3175; 41x11mm|
|989774||12 V||15 W||SV8.5-8||-||6451||207 lm||-|
|989775||24 V||10 W||SV8.5-8||-||6429||105 lm||41x15mm max|
|989776||24 V||15 W||SV8.5-8||-||6453||220 lm||41x15mm max|
|989777||12 V||5 W||SV8.5-8||C5W||6418||45 lm||37x11mm; see DE3022|
|989779||12 V||3 W||SV7||-||6428||29 lm||& 19925, 966850, ~DE3021|
|989780||12 V||1.2 W||SV5.5-6||-||6148*||6.3 lm||*Flosser 36x6mm|
|989781||12 V||3 W||SV5.5-6||-||-||26 lm||33x6.5mm max|
|989782||24 V||3 W||SV5.5-6||-||6444*||26 lm||*SV6-6 37x7mm|
|989785||12 V||20 W||BA9s||-||64115||450 lm||& 968113; center brake|
|989787||12 V||20/5 W||BAY15d||-||7241||440/35 lm||-|
|989788||12 V||21/5 W||BAY15d||P21/5W||7528||440/35 lm||& 182061, 966335|
|989789||12 V||21/5 W||BAY15d||P21/5W||7528||440/35 lm||-|
|989790||12 V||27/8 W||BAY15d||(SAE)||1157NA||370/20 lm||& 949281, no ECE equivalent|
|989791||12 V||27/8 W||BAY15d||(SAE)||1157||400/38 lm||& 989792|
|989793||24 V||18/5 W||BAY15d||-||7244||230/45 lm||-|
|989794||12 V||3 W||W2.1x9.5d||W3W||2821||22 lm||& 942571|
|989795||12 V||5 W||W2.1x9.5d||W5W||2825||50 lm||& 949671, 3278344|
|989796||12 V||5 W||W2.1x9.5d||WY5W||2827||30 lm||& 981184, 987945, 8679781|
|989799||12 V||1.2 W||W2x4.6d||W1.2W||2721?||6.4 lm||& 981671; ashtray lamp|
|989800||12 V||1.2 W||W2x4.6d||W1.2W||2721||6.4 lm||& 942327, 1323462; blu hldr|
|989805||12 V||1.2 W||W2x4.6d||W1.2W||-||-||blu hldr, 2721MF/2351MFX6?|
|989806||12 V||1.2 W||W2x4.6d||W1.2W||2721||6.4 lm||& 12798389|
|989809||12 V||3 W||B10d||-||64122MF||22 lm||& 969032; Brown socket|
|989811||12 V||55 W||P14.5s||H1||64150||1550 lm||& 942775, 980163|
|989812||12 V||55 W||P14.5s||H1||64150L||1550 lm||long life|
|989814||12 V||55 W||PK22s||H3||64151||1450 lm||& 944265|
|989821||12 V||65/45 W||P29t||HB1||9004||1200/700 lm||& 1312618|
|989823||12 V||21/4 W||BAZ15D||P21/4W||7225||440/15 lm||-|
|989826||12 V||65 W||P20d (90°)||HB3||9005||1860 lm||& 978278|
|989827||12 V||51 W||P22d (90°)||HB4||9006||1095 lm||& 978279; “55”|
|989828||12 V||55 W||PX26d||H7||64210||1500 lm||& 980556|
|989829||12 V||55 W||PX26d||H7||64210L||1500 lm||long life|
|989830||12 V||27/7 W||WX2.5x16q||PY27/7W||(3757A)||475/36 lm||& 980557|
|989831||12 V||10 W||SF6||-||212-2||100 lm||& 981445; (211-2 12W)|
|989833||85 V||35 W||P32d-3||D2R||66250||2800 lm||& 982452; Xenon HID|
|989834||12 V||42 W||PY20d||H10||9145||850 lm||& 983562; “45W”|
|989837||12 V||21 W||BAY9s||H21W||64136||600 lm||& 983584|
|989838||12 V||55 W||PGJ19-2||H11||64211||1350 lm||& 983612|
|989839||12 V||5 W||W2.1x9.5d||W5W||2825||50 lm||-|
|989841||12 V||10 W||BA15s||R10W||5008LL||125 lm||& 983330; long life|
|989842||12 V||21 W||BAU15S||PY21W||7507||280 lm||& 979623, 983331|
|989972||12 V||5 W||SV8.5-8||-||6413||45lm||41x15mm max; see 989777|
|999554||12 V||21 W||BAU15S||PY21W||7507||280 lm||“SV,” Mirrored; see 989842|
|999573||12 V||6 W||BAX9s||H6W||64132||-||(HY6W has BAZ9s base)|
Less info available. Often for switch and accessory illumination (see Neo-Wedge table). Some cross to six-digit Volvo numbers.
|3524511||12 V||1.5 W||-||-||2752MF?||-||Instruments bulb OSR_2439488A|
|3545170||12 V||1.2 W||-||-||-||-||Instrument/ashtray bulb|
|6846118||12 V||27 W||PGJ13 (90°)||H27W/2||881||477 lm||-|
|8620487||12 V||60 W||P20d||HB3A||9005XS||1860 lm||long life|
|9128743||12 V||W||-||-||-||-||blue holder (for 1.2w bulb)|
|9148906||12 V||W||NW4.6||17mm T||-||-||Switch bulb, 17mm T, white|
|9148908||12 V||W||NW4.6||8.5mm T[td]-[/td][td]-[/td][td]Hazard switch, grey[/td]|
Sorted by volts, base, then wattage for ease of comparison.
** As far back as 2001, many have suggested using Radio Shack 272-1092 "12V Microlamps" or any 7219 bulb and carefully re-wiring it into the old base. Others have suggested just buying Honda 35505-S84-N01 which already has the base attached. For even brightness, best to replace all at the same time on the radio and ECC, keeping working ones as spares.
3. C. Festoon Bulbs Use <ctrl+F> to Find your bulb number faster.
These Double-Ended (DE) devils often vary by base (cap size), length and diameter even among same voltage and wattage. Even with SAE, DIN, and ECE variations, this should help narrow things down* and rule out numbers for other voltages. The 1.2W vanity mirror bulb is conspicuously absent and non-standard.
3. D. Side Mirror “Approach” Bulbs Use <ctrl+F> to Find your bulb number faster.
Volvo describes the bulb for the side mirror or “Approach” light as “12.8 V, 11 W.” Aftermarket show others (e.g. 6W and 10W) some with 10mm glass, some with 16mm, but all with a W2.1x9.5d base (unknown if the 16mm will fit all housings). What ever is used, keep it below 11w. A W5W (2825) will work fine. Others one may encounter also shown for comparison. This photo shows the trick to getting access to them.
3. E. 3000-Series Bulbs
There is likely a good story behind the some of the redundancy for 3#5# bulbs, but I don’t have it. Some manufacturers list THREE different numbers on the same package in addition to A(mber) and K(rypton) variations. Double check the base and socket as noted below. (See Volvo table for bulbs in the 3000 range without a plastic wedge base, i.e. 3893 BA9s.)
Note: The manual for a 1998 S70 also lists 3357 NA, but due to Recall ID # 6397 - EXTERIOR LIGHTING:TURN SIGNAL Recall Date: DEC 06, 2000 "There could be inadequate contact between the bulb and socket which could cause the front turn signal not to function as designed. … Dealers will replace the left and right front turn signal [+ park light] bulb and socket.", one might encounter BAY15d sockets and 1157NA bulbs instead. I suspect a Volvo bean counter tried replacing two single-filament bulbs (front park and turn) and their sockets with one dual-filament. Since there was no dual-intensity amber ECE bulb, they tried an Ford-like amber 3#57 style bulb, but the cheaper plastic base didn't hold up under continuous use (night and DRL), began to give, and contacts got dodgy. The quick fix for the one-hole lens was for dealers to retrofit metal-base 1157NA (SAE) bulbs and sockets while going with two separate bulbs in the future. By contrast, Japanese automakers went with large all-glass wedge bulbs like the 7443NA (dual-filament, amber, and sometimes referred to as "WY21/5W" though not an ECE designation).
4. Older Volvos
For you older Volvo owners that see 67 and 1073 listed in your manual, you can safely swap them out with 5007 (R5W) and 7506 (P21W) which draw less power (Volts x Amps = Watts), put out the same or more light (lumens), and whose plated bases better resist corrosion. Here are other old designations one might find:
Old --> Current, P25-1 --> P21W , P25-2 --> P21/5W , R19/5 --> R5W , R19/10 --> R10W , C11 --> C5W, C15 --> C21W, T8/4 --> T4W, W10/5 --> W5W, and W10/3 --> W3W.
5. Common Questions
Why does Volvo sometimes list "1156" as a replacement bulb?
Some Europeans still think the buffalo freely roam the American plains, indians shoot arrows at people in the middle of their ten-hour drive from New York to Los Angeles, all our restaurants start with "Mc," and we do not have ready access to the correct ECE bulbs (P21W, R5W, P21/5W, 7506, 5007, 7528, etc.) despite the fact that European vehicles have been sold, serviced, and part of the aftermarket part supply chain for over half a century, and thus Volvo lists "US No." (SAE) bulbs in some owners manuals should we ever need one along the Oregon Trail to avoid dying of dysentery. Yet as shown in above sections, Volvo has made a LOT of mistakes in those manuals and 1156 is not the same as P21W (7506). Just think if Volvo also listed SAE nuts and screws (8-32, 1/4"-20, 1/2"-13, etc.) as metric replacements!
Can I use a higher wattage bulb?
Not recommended, and here’s why...
Increasing wattage (power) not only increases light (lumens) but also the infra-red (IR, radiant heat), ultra-violet (UV), and conducted heat (transmitted through the bulb from the glowing filament to the socket) that all filament bulbs produce leading to hazing, crazing, melting, discoloring, and or embrittlement of the surrounding plastics with time. It also puts the circuit in a state of overcurrent. Going from a W3W to a W5W increases the load by 40%, so if the FoS and effects of age or conditions put it around 140%, the circuit’s ampacity will be exceeded leading to “immediate or progressive deterioration.” By the time that +40% over-watt bulb fails, the condition of surrounding components are seldom as good as when the OEM bulb was removed.
Telltale pointy tip on halogen bulbs. Can I “upgrade” to a mini-halogen bulb?
By taking advantage of the halogen cycle, these bulbs give off considerably more heat which damages components not designed to handle it. If the wattage is the same, the lens glass, reflector metal, and socket metal or other high-temperature non-plastic material, it might be fine. Feel the lens when it’s first turned on, after a minute, again after five minutes, then turn it off and feel the reflector and socket. Compare it those results to the stock bulb, but even then halogen damage can take months to detect.
Any downsides to brighter tail lights?
In addition to the above, it can make it more difficult for following drivers to detect when you’re braking, especially if they can’t see all your lights (e.g. two cars behind).
Are blue-tint bulbs better?
No, they are always worse.
Bulbs produce a spectrum of light, the average of which we perceive as its “color.” Any tint always reduces output because to change the “color” it has to filter out part of that spectrum thereby reducing overall output (lumens). Mimicking color never mimics output no more than your red Check Engine Light is as “bright” as your red brake light. Daniel Stern has more on blue bulbs and how tinting can drop output from “1,550 lumens to 1,380 lm” by switch from a standard clear glass to a “Super White” bulb.
How did blue-tint bulbs get started?
Tinting bulbs is a cheap way to make a cheap bulb have the color, but not the output (lumens), of over-watt halogen, xenon, HID, or other more expensive bulbs. PIAA is blatantly the worst at this with claims like “55w=100w,” but as watt is a SI unit, that’s just as impossible as saying the same with a different unit like “55 meters = 100 meters,” “55 seconds = 100 seconds,” or “55 kilograms = 100 kilograms.” If you stare at a color then look at a white wall, the after image will appear in the opposite color. If you’ve been viewing the road via the slightly yellow color that halogens have and then see a whiter light such as a fluorescent or HID bulb, it will appear as if it is tinted blue (and conversely halogens will look “yellow” from an HID perspective), even though it is not. You may have noticed that even halogen lights appear bluish if your prior frame of reference has been a sodium vapor street light. Some manufacturers then cashed in on false association between “blue” and higher performing bulbs with “Super White” versions of regular bulbs. Some then took "blue" to all new levels (not the color you want authorities to see you running).
Can I swap out a halogen headlight bulb with a “HID conversion” bulb?
No. HID conversions must include the bulb, lens, and reflector because the halogen light-source is a straight line (filament) whereas a the HID’s is a curve (electric arc that rises in the middle due to heat). More about “HID conversions” here.
Are HID lights better?
Well, better at what? There are many factors. Reduced power consumption (watts)? Yes. Cost to service or replace a bulb? No. Gross output of light (lumens)? Yes. Quality of light for the human eye? Considering that spectral sensitivity of the human eye is between 555nm (day) and 507nm (night) depending on conditions, yellow-ish light may actually be better (think thousands of generations adapting to campfire light at night). And as lights produce not just one color, but a spectrum of light (the average of which is the perceived color) one has to consider the color rendering index (more here). Yet, instead of discussing wavelength nanometers, CRI, spectral sensitivity, and human eye anatomy, it sure is easier for a salesman to say HID is “like the color of DAYLIGHT! Who can beat the sun!” despite the fact that headlights are needed for NIGHTTIME lighting conditions.
Should I switch to LEDs?
In short, no. Save your time and money for now. In addition to the factors mentioned for HID, especially the need for the lens and reflector to be designed around the type of light source, remember that LEDs are “narrow” -- narrow spectrum and narrow focus. Their directional light does not radiate in all directions like incandescent bulbs, as seen when comparing LED and incandescent brake lights from the side. Interior LEDs can have a poor CRI for reading maps. Note how auto makers have to pepper the area behind a tail light lens with multiple LEDs to cover the same area one bulb can do along with a reflector. Some LED vendors have responded with LED “bulbs” where the LEDs are mounted at different angles to shoot light off the reflector, but this is like trying to replicate the even “fur” of reflected incandescent light with a lot of spikes. Note how no auto maker who has to meet DOT, SAE, or ECE standards uses LED “bulbs” in incandescent reflectors, only arrays. Though maturing in the OEM market, the aftermarket is still in the unregulated and non-standardized “Wild West” phase. Note how bulb manufacturers are tooling up for LED bulb-retrofits without a ECE, SAE, DIN, DOT, ANSI, ISO, or other standard to go by, which insures that a “bulb” type 123 sold by one vendor will operate the same as a 123 sold by another. The aftermarket thus tries to coattail or piggyback off an existing specification to label the LED (i.e. "194 type") despite that one can't replicate the specs of the other. Referring to sockets or bases by a bulb ("194 base") versus W2.1x9.5d is another red flag, just as if a vendor described a 15" wheel using a tire size ("205/70R15").
Do fog lights (front) and fog lamps (rear) really do anything?
Fog lights are designed to shoot under the fog to illuminate the road while driving at a slower speed... because the visibility is reduced. Fog lamps are the same intensity as brake lights to be spotted from farther behind but are closer to the vehicle’s centerline. Volvos usually have just a left fog lamp for left-hand drive vehicles (right-side of road) and vice versa. As Volvo notes, please use them only under reduced visibility conditions, like when it’s harder to see the cars in front of you. Otherwise, they’re as “cool” as driving for miles with the turn signal on, can be mistaken with a brake light, and might make police think you have a “defective (brake light) equipment.” Bookmarking that page in your owners manual may prove handy. Check out these two pages on front fog lights and rear fog lamps.
What do “SV” and “DC” mean after some Volvo bulb descriptions?
Both Philips and Osram/Sylvania have offered amber bulbs with a mirrored, silver, or chrome finish through their Silver Vision (SV) and Diadem Chrome (DC) lines respectively. The idea was to eliminate the “fried egg” look of an unlit amber bulb behind a clear lens. The challenge is making sure they are as bright as standard amber bulbs when illuminated and some have noted other versions are noticeably dimmer. Osram/Sylvania also has a Diadem line that has an “opal” or oyster-shell appearance when off.
No bulb costs more than a “defective equipment” ticket and court costs, nor should take longer to change than a traffic stop.
Make a routine of checking your bulbs. Multi-task them into other regular activities like unloading groceries or talking on your phone in a parking lot so you spot bad bulbs before the fuzz does.
Use glass storefronts at night as a big mirror to check your brake and reverse lights while in your car.
Look low, not high. The correct ECE bulbs for common uses have FOUR digits, start ABOVE 2700 and thus will be LOWER on numerically-ordered racks at parts stores and supercenters. Gas stations and grocery stores seldom carry more than a couple types, so buy spares before a road trip.
Don't start at the top left of a dizzying 15 x 8 display like this looking for a visual "match." That P21/W5 (7528) that will be the 120th and LAST one! Avoid a string of misses before you get a hit by using the cheat sheet numbers at the top or tables. Headlight bulbs (9000-on and H-codes) get their own section. Don’t mix bulbs. If you replace one SAE tail light bulb with the correct R5W (5007) one, check the other ones too. Unbalanced electrical loads can have strange symptoms or appearances.
Search the socket, lens, or reflector for a ECE bulb designation so you get the right bulb (see “SHORT VERSION” and “2. Confusion Examples and Avoidance” above).
Replace bulbs in pairs. Bulbs dim with age. If one side went, the other is probably close and can look dimmer than the new one on the other side. The used one can always be put back in the package, marked as “used spare,” and kept in the trunk.
Don’t let spare bulbs rattle in the package. Crumple a piece of paper towel or plastic bag behind them so you don’t find the filament broken or amber paint flaked off when you need them.
Smear a little di-electric grease lightly on the bulb contacts, especially if you spot any corrosion. It is non-conductivity prevents the grease from creating a short while providing an oxygen barrier to reduce corrosion that inhibits performance. Corroded sockets and connections are best cleaned with Caig DeoxIT®, though a pencil eraser or the finest sandpaper may help in a pinch.
Keep your fingers off the glass. Use a paper towel or plastic bag to hold the bulb glass and wipe clean of fingerprints, dirt, or grease afterward. Wipe halogen and headlight bulb’s glass clean with rubbing alcohol if touched to avoid hot spots that shorten its life.
Learn how to get to and replace bulbs while you have light and warmth. Do NOT resort to twisting screwdrivers as levers. If you’re reading this, you are likely disregarding Volvo’s admonition of: “The following bulbs should only be replaced by a trained and qualified Volvo service technician: Dome lighting, Glove compartment ... Footwell lighting ... Turn signals in the door mirrors ... Approach lighting in the door mirrors ... Brake lights/rear fog light/taillights, Rear parking light.” Ea$y money for the dealer$! Hour’$ labor for minute’s work. So, look for telltale cut outs for catch tabs that indicate where you should press in, go on-line, and ask others. Use a tool to unhook then PULL the lens out gently instead of damaging the area around by twisting and levering screwdrivers. A plastic bone tool is even better. Volvo’s mantra of “insert a screwdriver and pry, turn” guarantees dealers a steady stream of replacement lens sales. For example, the red lights on the end of the doors are often broken via this method when they actually slide up just a bit (“Volvo” logo on top) against the plastic spring, before the bottom can be pulled free with a fingernail. On padded door ends, they clip into a plastic piece versus the metal frame and often flex into the inside of the door preventing the light from catching, leaving them to get smashed when you close it. The trick is to use a tiny screwdriver or pinpoint tool to hold the top catch until you can hook the sprung “Volvo” end, then do the same with the bottom one. By doing the top first, the spring gives a little more wiggle room to get the bottom one hooked. If padded door panels are ever removed, look into securing the clips better. Inspecting and replacing bulbs before you “need” to.
Working bulbs needing replacement because...
Turn signals are getting whiter? The paint is going. Address it while it's still a legal color. Stained glass has used cadmium for amber, but bulbs are painted now due to toxicity. They could be wiped clean with thinner before re-painting with Krylon "Stained Glass", Granville "Amber Light", or Tamiya TS73 "Clear Orange", but end color, resulting lumens, and longevity are unknown. Unless you'll use them for other things, it's cheaper and faster to just buy new PY21W (7507, note pins) and WY5W (2827) bulbs. 7. Useful Links
Tip of the Hat: DonsBulbs.com is very good at listing many of the specs for bulbs.
Links to electrical terms:
HowStuffWorks.com: What are amps, watts, volts and ohms?
Volts (V), electric "force": http://en.wikipedia.org/wiki/Volts
Amps (A), electric current: http://en.wikipedia.org/wiki/Ampere
Watts (W), electric power (e.g. power used, not light produced): http://en.wikipedia.org/wiki/Watt
Ohms (Ω), electrical resistance: http://en.wikipedia.org/wiki/Ohm
Candlepower (cp), light's intensity: http://en.wikipedia.org/wiki/Candlepower
Lumens (lm), perceived light: http://en.wikipedia.org/wiki/Lumens
Abbreviated Trivia: V, A, and W are capitalized because they were named in honor of Alessandro Volta, André-Marie Ampère, and James Watt respectively.
Edits: Typos, formatting, links, better pictures, and more that only someone who would write this would notice.