Question about Lamp Failure Sensor on 1993 Camry

[oxymoron]

I have a 1993 Camry and the tail lights have stopped working. The brake lights do work. I read that this can be caused by a short in the Lamp Failure Sensor and that it should be located on the left hand side of the trunk under the carpet liner, but I can't find it. Am I looking in the wrong place?

EDIT: I found another message that said the box is located under the antenna and should be green or blue (rather than yellow like the previous messages I read). There is a box there, but it's black. There's also a bundle of wires with a blue plug that fits into a blue socket above the box, but the plug isn't connected to it. There are wires coming out of the bottom of the black box. Plugging the plug into the scocket doesn't have any effect (the tail lights still don't work and the others still do). Is this box the lamp failure sensor? Is it possible that the car's previous owner replaced the sensor and that's why it's black? And why would the top plug not be plugged in?

[jaswasup]

I AM currently selling one on ebay for like 9 buks
It is yellow an i have seen them in white before
It is on the drives side behind the carpet up by the trunk lid hinge

[Stillrunning]

You might want to make sure it is not the brake light switch first.

[Mike Gerber]

Before doing anything else, I would open up the loom of wires inside the trunk by the driver's side trunk hinge. Look for frayed or broken wires in there. Repair them as necessary. Many times the wires inside that loom break, due to all the flexing that loom is exposed to from all the opening and closing of the trunk. Many problems with lights in the rear can be traced to broken wires inside that loom.

Mike

[oxymoron]

Originally Posted by Stillrunning

You might want to make sure it is not the brake light switch first.

Do you mean the black box might be the brake light switch, or that the problem might be caused by the brake light switch? Where is the brake light switch?

Also is the black box the Lamp Sensor Failure or is it something else? I looked under the carpet on the left hand side and there's nothing there.

EDIT: I found the Lamp Failure Sensor. I opened it and one of the connections is fried. I resoldered the connection and the tail lights came on, but the wires heat up and begin to burn. What could be causing this to happen? Is something actually wrong with the sensor, or could it be the wiring that's plugged into it? Obviously I don't want to buy a replacement sensor and have it break. I'm also weary because one of the mechanics I talked to said that the part alone would cost $275, but everything I've read has said it's only about $190.

[Kingdom934]

Go to the junk yard and pull one. It should cost half of what you can get one new I believe.


If it's melting as soon as it is connected, it could be the soldered is a weak point in the circuit, thus it melts or there is some kind of shortage or overload from what I'm thinking. Wires just don't melt for no good reason...seems like it went out to protect against a more worst thing...like melted wires.

[Stillrunning]

I would still do what Mike Gerber suggested. That could be the cause of your short. If you don't find any wires in the loom frayed then replace the sensor with one from a junk yard. I would open up the replacement and watch it for burning wires as you apply the brakes to make sure the problem isn't elsewhere.

[Qslim]

Originally Posted by oxymoron

Do you mean the black box might be the brake light switch, or that the problem might be caused by the brake light switch? Where is the brake light switch?

Also is the black box the Lamp Sensor Failure or is it something else? I looked under the carpet on the left hand side and there's nothing there.

EDIT: I found the Lamp Failure Sensor. I opened it and one of the connections is fried. I resoldered the connection and the tail lights came on, but the wires heat up and begin to burn. What could be causing this to happen? Is something actually wrong with the sensor, or could it be the wiring that's plugged into it? Obviously I don't want to buy a replacement sensor and have it break. I'm also weary because one of the mechanics I talked to said that the part alone would cost $275, but everything I've read has said it's only about $190.

[oxymoron]

Thanks everyone. I'm not sure if I explained what happened very well so I took pictures.



The arrow points to where it was burned. The solder on the lower connection was also blown off. This is where I bridged the gap with solder, but I removed it after what happened.



This is the back. It wasn't burned this badly before but it was definitely burned. The two wires here are the wires that heated up (ie glowed bright orange - I could see it through the crack around the opening in the case).

I hope this makes it clearer? When I soldered over the gap, the tail lights worked properly, but obviously something else is wrong because the wires overheated instantly. Does anyone know if this indicates a problem somewhere else? Could it be a problem with the wires attached to the hinge? (How do I check to see if a wire is frayed without removing the insulation?) There's clearly electricity going through, but I don't know very much about electronics - what could be causing it to overload like that? Is it because the trace between the points is so burned? (Why can't those wires just be connected directly to each other? Sorry like I said I don't know much about electronics )

I guess I have to get a replacement since this one is so fried but if there's a problem somewhere else I don't want to risk ruining it the first time I plug it in...

[dc_98_cam]

Could you have caused a short circuit with your solder repair?

Try this:

With the lamp failure sensor removed, locate the green and light green wires going into the sensor plug connector. Temporarily splice these together. ... The tail lights should work, and remain working, if there is no problem, such as a possible short circuit in one of the tail light sockets or at some other point in the wiring.

If there is a short circuit someplace besides the lamp failure sensor, you will probably blow out the 15 amp tail fuse when you splice the wires and turn on the headlights. At least you will have a better idea as to where the problem is located.

When looking for a possible short circuit, examine the wiring and connectors and sockets for discoloration, or any signs of warping due to excess heat. Try touching the tail light sockets to see if they are excessively warm.

If the tail lights work with the wires spliced together, then just repair or replace the lamp failure sensor and restore the green and light green wires to their original arrangement.

[N35QU!K]

I have the same problem. My tail light error indicator is always on... All the lights work fine, but my gf's dad, who's a mechanic, recommended I replace all the bulbs, just to get rid of the indicator, and all the tail lights work fine... But the indicator is still showing. WTF.

[dc_98_cam]

Originally Posted by N35QU!K

I have the same problem. My tail light error indicator is always on... All the lights work fine, but my gf's dad, who's a mechanic, recommended I replace all the bulbs, just to get rid of the indicator, and all the tail lights work fine... But the indicator is still showing. WTF.

This sounds like it might be a problem on the light failure sensor circuit board.
Probably replace the light failure sensor box to fix ... or maybe figure out what's wrong with the original. Can you post a well focused picture of the component (part side) of the board?
If there is something simple like a transistor, you can solder in a new one. If there is some sort of custom made integrated circuit, you might not be able to find a replacement.
.... Then the best fix might be to try to get a new light failure sensor from the salvage yard.

[N35QU!K]

Its on the left side of the engine temp gauge, in the very bottom left corner, and its a car with little lines coming out of the tail.

[oxymoron]

Originally Posted by dc_98_cam

Could you have caused a short circuit with your solder repair?

It's possible, but since the board was already burned around those two wires, and there's no damage to the parts of the board where the plug connects to it, I think something caused those wires to heat up before and that's why the connection blew out in the first place.

Originally Posted by dc_98_cam

With the lamp failure sensor removed, locate the green and light green wires going into the sensor plug connector. Temporarily splice these together. ... The tail lights should work, and remain working, if there is no problem, such as a possible short circuit in one of the tail light sockets or at some other point in the wiring.

Is it safe to do that? I'm kind of hesitant to strip the wires in there.

I've found a local used parts dealer who has a lamp failure sensor and I'm going there later to get it. Do you think it's safe to try plugging the replacement in and see if the wires heat up? (The burning wasn't really instantaneous - if it started to heat up I could just turn it off). Obviously I don't want to ruin the replacement but splicing the wires together is kind of scary. But I will at least check and see if they show any signs of having overheated.

[dc_98_cam]

Is it safe to do that? I'm kind of hesitant to strip the wires in there.


You don't actually solder the wires together. You get a length of 12 or 14 gauge wire with alligator clips on the ends. You remove a little insulation at a convenient point on the green and light green wires going into the sensor plug. Then, cautiously, you turn on the lights and try to tell if everything is okay ... or not. You might burn out the 15 amp tail fuse if there is in fact a problem short, but that fuse is there to protect anything else from damage.

The light failure sensor is just a sensor device that monitors the amount of current going in and going out. The green wire is the current going in, and the light green wire is the current going out. .... No problem connecting these two wires together.