2005 Prius Brake Light dim problem. Light assembly or electrical?

It could be either, but I would first suspect the wiring. Why not disconnect the offending light and connect it directly to the 12V bus? It should be at full brightness if it is a wiring problem.

Tom

 

Since you say that 1 out of 6 LEDs is bright while the other 5 are dim, then it sounds like the whole assembly will need replacement - unless you know how to get to the circuit board, and locate/repair an apparent intermittent connection.

All 2G should have the same removal/replacement process.

 

There seems to be a lot of discussion, but no definite fix yet. I'll add my observations since my 2004 just developed the same problem. The left side (driver's side) brake light was very dim, almost to the point of not visible. I tried reseating the connector, but it's hard to see and I couldn't tell how the latch might be working. A couple of tries with no success, then one time four of the LEDs lit up normally. When I took my foot off the brake and pressed it again, back to all dim. After reading the posts I went ahead and ordered a replacement tail light assembly online. Tonight I was pulling out of a parking place and saw a reflection of my tail lights in the storefront window. Both brake lights were working again. On closer inspection, one of the LEDs on the troublesome tail light was out (actually dim). I'm going to go ahead and replace the assembly since it seems like one bad LED can disrupt the entire array. Too bad Toyota didn't think ahead, I could live with one or two LEDs burned out.

 

I have said this before, the design is poor, and was not done by an EE. They put LEDs in parallel, without a series balancing resistor. If one LED fails, it can kill the one in parallel with it since it tries to force 2x the current through it.

 

I have a 2005 and the passenger brake light LED's started getting dim. After reading the posts, I ordered a new one and installed it today. A few words of advice - I shopped for a new brake light assembly on amazon. I found a great deal from PartRunner - http://www.916autoparts.com/ $110. The part came in a genuine Toyota box so it is an OEM part.

I used the instructions on the Forum for removal of the driver's side brake housing to do the passenger side. Be careful when removing the 10mm nuts that hold the housing in place as I dropped one and it went behind the battery. It took a while to locate it and get it out.

The new brake assembly fixed the problem - everything working fine now.

 

They think LED can last forever. However odd ones are there. Glad that rue got a cheaper one.

 

Do all taillight assemblies that are being sold include the brake LEDs and circuit board?
Is it possible to buy a replacement LED / circuit board unit without buying the rest of the taillight assembly?

Thanks,