1) Cleaned inside connector (wire harness) with CRC contact/connector cleaner; especially slot#3. Visually I now see copper instead of corrosion..
2) Jumped connector slot#1 to 3; but still no brake lights.
Looked for Light Failure Sensor. (1) Looked in trunk on driver side or left side, (2)removed cover, (3) found black box, (4) saw 6 wires (yellow+blue, blue+red, blue+red, black, and white) all attached to a connector. Problem, I did not see a green+white wire.
Also saw a yellow box.
Plan to look again tomorrow. I wrote down the wire colors (based on the wiring diagram)which I should see connected to the sensor. If I can find the sensor I plan to do the tests as instructed.
But if the black box above is actually the sensor please let me know.
Yes. Previously I did look at the videos. The first one was so quick I did not fully realize what I was looking at.
Yesterday I looked in trunk for the sensor. However now I realize I was looking at IT ALL THE TIME; The YELLOW BOX. Also this morning I looked in my 1987 Toyota Repair Manual in Body Electrical Section and there is a drawing of the car, and there was the sensor. It was hiding in plain sight all the time! My mistake. I plan to do tests today; weather permitting.
Now I am trying to remove the Light Failure Sensor(the yellow box). Problem:
1) Only small part of it is visible from the side; it is almost entirely hidden behind a metal panel.
2) I can reach in and grab it in my hand.
3) It feels (I said feels because I CANNOT SEE WHAT'S INSIDE)like sensor is attached to an L (upside down)shaped metal hanger.
4)I pressed all around sensor top to find a release tab to slide it off the hanger; but it will not move.
5)Checked YouTube found video->"Lamp Failure Sensor Fix 1990 Lexus ES 250". In the video the guy removed the trunk carpet cover on that side and he had nothing blocking access to sensor; however not me I have a metal panel blocking visual access to almost all of the sensor.
I will keep working at it.
If I can remove the sensor I plan to do the voltage measurements you recommended.
Finally got sensor to release. Thanks Mobile Dan, dabunk and grcauto.
Mobile Dan, Billr, and grcauto
I did the previously recommended voltage tests:
1) Jumper Brake Lights Switch connector (brake light switch bundle) slots #1 and #3. Took voltage reading at Light Failure Sensor connector white+green wire(using a small paper clip) reading->13.56 volts.
2) Removed jumper. Reading at Sensor white+green wire->0.06.
1) The tail lights work good. The only problem appears to be the brake lights. .
2) There is a dashboard warning light which is the icon of a car with the rear lights on. This light has been on for years but I have ignored it because the rear lights (tail, brake and direction) had worked fine until the recent brake light problems.
Pin 9 Ground; confirm it is staying at near-zero volts when any lights are trying to be turned on
Pin 10 left tail and marker; confirm that it goes high simultaneous to either pin 2 or 3 going high
I think we are going to find the module is bad.
Also, note that there is a great difference between a "GRN/WHT" (looks green on casual inspection) wire and a "WHT/GRN" wire (looks white); get in the habit of not swapping those labels, as you did in reply #55!
From what I read all over the internet, those lamp failure modules are VERY problematic. Some folks have rewired and eliminated the module altogether. And here are various diagrams that have and have not worked. Of course, replacing the unit is expensive at over $200, but there are many used ones on ebay. Of course, those could be as bad or worse than yours.
Billr and grcauto,
Yes. The tail lights WORK (turn on the lights and you get (1) the tail lights on both sides, (2) two rear license plate lights, (3) side lights near the rear on each side of car_which I think are called side marker lights). However the brake (stop) lights are NOT working. Previously, with all the lights off when I jumped the brake switch connector (wiring harness) slots#1 to 3 the brake lights should have lit immediately(I think), but they did not light.
Any more questions please let me know.
I appreciate your comments. When I was trying to release the sensor (module) from the flange which held it, since I could only touch it but I couldn't fully see it, I checked RockAuto to see what it looked like( a trick I learned from MobileDan) and I could not find it. And I looked multiple times.