Third/midle Brakelight On 2000 Rx Not Working

[crownroyal53]

My tihird brake light on 2000 rx 300 has been working since I bought the truck brand new. About three months ago, I noticed on my dash board a light blinking intermitently everytime I applied my brakes. I checked every lightbulb at rear of my vehicle, it turned out that the only bad lightbulb was my third brakelight bulb.

I replaced the bad bulb with a new bulb purchased from Lexus dealership. The third brakelight refused to come back on when brakes applied, I took my truck to my mechanic who checked the relay located in door panel by the left passenger seat for correct voltage and flow, Everything checked out up to that point. Then he checked for volttage from the relay to the third brake light itself, Again, he recorded correct voltage and flow. But when he put a new light bulb in the unit, again, no light. Could someone advise me what else could be wrong with my third brake light?

[lenore]

it may be as simple as the contacts that press against the bulb are spread apart and not making good contact. Either that or they are corroaded.

[jaswood]

My tihird brake light on 2000 rx 300 has been working since I bought the truck brand new. About three months ago, I noticed on my dash board a light blinking intermitently everytime I applied my brakes. I checked every lightbulb at rear of my vehicle, it turned out that the only bad lightbulb was my third brakelight bulb.

I replaced the bad bulb with a new bulb purchased from Lexus dealership. The third brakelight refused to come back on when brakes applied, I took my truck to my mechanic who checked the relay located in door panel by the left passenger seat for correct voltage and flow, Everything checked out up to that point. Then he checked for volttage from the relay to the third brake light itself, Again, he recorded correct voltage and flow. But when he put a new light bulb in the unit, again, no light. Could someone advise me what else could be wrong with my third brake light?

Inside that "relay" is a current flow sensing resistor so the ECU can monitor if the high mount brake light bulb draws current when the brake is used. If the OEM bulb was shorted for a long period of use then the resistor link might have been burned open. Due to the design of the "relay" circuit normal voltages would be present except with the bulb load in place.

[jaswood]

My tihird brake light on 2000 rx 300 has been working since I bought the truck brand new. About three months ago, I noticed on my dash board a light blinking intermitently everytime I applied my brakes. I checked every lightbulb at rear of my vehicle, it turned out that the only bad lightbulb was my third brakelight bulb.

I replaced the bad bulb with a new bulb purchased from Lexus dealership. The third brakelight refused to come back on when brakes applied, I took my truck to my mechanic who checked the relay located in door panel by the left passenger seat for correct voltage and flow, Everything checked out up to that point. Then he checked for volttage from the relay to the third brake light itself, Again, he recorded correct voltage and flow. But when he put a new light bulb in the unit, again, no light. Could someone advise me what else could be wrong with my third brake light?

Inside that "relay" is a current flow sensing resistor so the ECU can monitor if the high mount brake light bulb draws current when the brake is used. If the OEM bulb was shorted for a long period of use then the resistor link might have been burned open. Due to the design of the "relay" circuit normal voltages would be present except with the bulb load in place.

Just to be sure...the "relay" I refer to is mounted just behind the driver side rear wheel on the inside of the cover on which the 12 volt alternate plug is mounted.

[dcortese]

2001 RX300 185000 miles and original owner.

In trying to resolve a similar problem with the high mount brake light over the past 6 months, I've found several other possible solutions. First after several replacement bulbs attempts,  the high mount would not light.  Ultimately, I found that the bulb socket was bad, a connector at the bottom was broken/missing.  Finally found the part without having to buy the assembly - Pt # 90075-99005.  Put a new led in, low and behold the light works!  Except that the dashboard warning light didn't disappear as  hoped/expected.

After reading the car's electrical system is 'sensitive' to the particular bulb, in this case a Sylvania 921, I put the OEM bulb in and now have an warning light free dash.

For all, good luck.