Can't Get The "bulb Is Out" Dummy Light Off...

[Raine.]

Picked up a 95 SC300 a couple of weeks ago, the "bulb is out" dummy light was on, and I noticed the left upper bulbs on the left tail light (168/194 bulbs) were out, so I replaced them - but no go. The bulbs I installed were new, but they're not lighting up. I did a visual check on the tail light harness and so far everything seems untouched. I was thinking of splicing the left two sockets (the two that are out) to the right two sockets (these work fine), but I'm not sure if the bulbs are in some sort of loop or specific wiring configuration that allows the 'blub is out' light to come on in the first place. Can anyone point me in the right direction?

[SKperformance]

Did you check for any power on the harness sockets with a volt meter?

[Raine.]

Did you check for any power on the harness sockets with a volt meter?

Checked voltage, all is good. I found out that the bulbs I put in were bad (newb mistake), so I bought a new pair of bulbs (194) and the lights are all on.

BUT THEN...

...took a 20 minute drive after replacing the bulbs (and checking every other one) and the dummy light came back on. I read that the factory bulbs are of a slightly lower voltage (3w vs. 5w for replacements, or something like that), could this be causing the taillight module to think that there are bulbs out?

[calbsc400]

I'm wrestling with the same problem. All the rear lights are working but the parking lights are on the same circuit and I'm in the process of changing out burnt bulbs. It's a real PIA, you have to pull the whole headlight assembly to change the parking light bulbs. I guess if you have real small hands and are real agile you can do it without pulling the headlight assembly.

The point being: I read in these forums somewhere that this warning light is activated by current draw in the circuit. When the current draw drops, i.e. burnt bulb, the light comes on.

I had three bulbs out, drivers side marker, drivers side parking and passengers side parking. Once I get the motivation to go after the passengers side light the warning light should go off. Maybe

Good Luck

[Raine.]

Searched the rest of the forum, and found this:

Folks,

This is a common problem I have seen in Lexus. The sensor is triggered by current output so a weak or incorrect bulb will trigger the alert... For 95 and greater, make sure to use 138 instead of 194 bulbs. 138 have slightly higher output and that is the correct bulb.

I wonder if this is the reason why my dummy light is still on, as I used 198 bulbs... I'll try finding some 138's.

[calbsc400]

The application guide in the parts store calls for 168. Now what? The owners manual calls for a 5Watt bulb but no number and none of the bulbs in the store seem to rated for watts.

[Micah]

I had that problem. Heres what I did. I didn't want to troubleshoot 10 or 12 bulbs so I went to Wal-Mart and bought the long life bulbs. I replaced every single bulb in there and also unplugged the taillight sensor near the antenna and replugged it in to kind of clean the connections if there was anything on them. I now rarely have the light come on, but I think it has something to do with the alternator or battery. I think that there is not quite enough power at night when all lights and accessories are on b/c the light doesn't activate when I turn the a/c or radio or any accessories off. Also, I only comes on when I reverse AND have the brakes pushed. I would suggest just replacing every single bulb with the sylvania brand bulbs at walmart. That is what I did and have had no trouble.

BTW, I used 194s for the parking lights and whatever the computer at walmart told me to use for the stop lights.

[Raine.]

I had that problem. Heres what I did. I didn't want to troubleshoot 10 or 12 bulbs so I went to Wal-Mart and bought the long life bulbs. I replaced every single bulb in there and also unplugged the taillight sensor near the antenna and replugged it in to kind of clean the connections if there was anything on them. I now rarely have the light come on, but I think it has something to do with the alternator or battery. I think that there is not quite enough power at night when all lights and accessories are on b/c the light doesn't activate when I turn the a/c or radio or any accessories off. Also, I only comes on when I reverse AND have the brakes pushed. I would suggest just replacing every single bulb with the sylvania brand bulbs at walmart. That is what I did and have had no trouble.

BTW, I used 194s for the parking lights and whatever the computer at walmart told me to use for the stop lights.

I think I'm gonna try replacing all taillight bulbs this weekend, see if that does anything

[calbsc400]

That's what I was going to do, replace/check all the bulbs. I know all the bulbs work now but I just checked the Alt output and it is low, 13.0 Volts - Norm 13.5 Volts - Strong 14.0 Volts. Hasn't failed but headed that direction anyway. I think I better quit spending money on bulbs and start saving the alternator. I just, 3 weeks ago, replaced the alternator in the car this Lexus is replacing. Damn

PS Now that all the bulbs are functional the light does come on a little slower. It used to come on immediately when the lights were turned but now there's a little pause.

[Micah]

Mine stopped coming on after I fixed my electrical problem in the drivers door wiring harness. Toyotas seem very sesseptible (hope that's the right spelling) to wiring problems. I had a camry once that an aftermarket alarm was making it surge every now and then when at a stop light. An electrical problem that has nothing to do with the tail light system could be affecting the sensor. I know that my alternator reads b/w 12.9 and 13 volts (according to my bel radar detector). I probably should consider checking mine too.

[vettenut72]

Make certain to check the Center Mounted High Brake Lights. Mine did the same thing until I replaced those and fixed the wires up there.

Joel

[calbsc400]

Found another burnt bulb that was actually in the taillight's! Are there enough bulbs in each tail light - 3 5 watt running lights, Two Brake Lights, One turn signal and one reverse. Idiot light is still on. I may just have to learn to live with it.

[Scott Yoo]

I've had this problem, as well. What I found was corrosion in the socket that attaches to the bulb. The older SCs had a condensation problem in the rear lights. Corrosion=bad connection or short circuit, which = blown bulbs.

I've resigned myself to having the idiot light on, although a friend told me to swap out my rear taillights with a 96 or later, as they were redesigned and don't hold moisture.

Hope this helps.

[Raine.]

Well I got a new owners manual in the mail today, and after reading through it, it does say 5.0 watt bulbs for the parking lights.

I did some more reserach, and found the following:

- type 194 wedge bulbs (the ones I used) are rated at 3.78w; that's 1.22 below 5.0w.

- type 168 wedge bulbs are rated at 4.9w, still 0.1 below factory specifications.

- type W5W wedge bulbs are rated at a full 5.0w, but are ECE (European standard) and might be hard to find in the U.S. (I haven't searched around yet)

Now then, since the "bulb out" circuit measures current draw, it's possible that if you switch to type 168 bulbs on all locations, the dummy light will go off, depending on the sensitivity of the current draw circuit. Some people have said that they replaced all bulbs and this worked; it's safe to assume that if they were all "off the shelf" wedge bulbs from an auto parts store, that they were type 168 bulbs.

That said, if I don't find a convenient and resonably priced place to get W5W bulbs, I think I'm going to try going type 168 for all the parking lights :)

EDIT: W5W is also known as a type 501 wedge bulb.

EDIT 2: There are many places in the U.S. and on Ebay to get type 501 bulbs, I'm going to get a set and it should fix the problem =)

[anthonyiez]

w/o reading all the responses, so forgive me if this has been said.

i once had a 95 sc400 that 194 bulbs would work fine, but the warning light wouldn't go out. turned out, that the correct toyota bulb was a 192. got a set from toyota and problem solved. now like i said this was a one shot deal and i've never ran into it again.

[calbsc400]

Finally success!!!!!! Replaced all the parking light bulbs with the #168's. What a hodgepodge of bulbs came out. Two were the 5W5, a couple 158's, 191, 194 and other misc. I'm real happy that it's fixed though, idiot lights drive me batty.

[Raine.]

^ I ordered a 10-pack of W5W's (to have some extras) and I'm positive this will fix the problem