RomanTPA

So my 01 developed this issue where for the first few minutes after start up the brake failure message comes on when I hit the brake pedal.

This only happens for the first few minutes of the car running. Stops doing it after car is driven for 5-10min

Only when the headlights are on and car is either in D or R. It doesn't do it when the engine is off or car is in P.

Every single bulb is working, including all of the tiny bulbs in headlights, all of the bulbs in the trunk and center high light.

There are no LEDs in the car.

I'm tired of this and would like to bypass the module, but I don't know where it's at or how to get around it.

Tom57

Before you bypass the module, change all dual-filament rear corner brake bulbs, as well as the high-mount 3rd brake light bulb, even if they appear to be good, and work intermittently. I had this problem due to a very small break in a bulb filament.

StanVanDam

The light failure sensor is in the "Luggage Room J/B" ECU.

I'm sure you already know this, but incorrect bulbs or bulbs that are on their death bed can fit, light up, and appear to be working fine, but are actually creating an out-of-spec condition on the detection circuit. There are several bulbs in the LS430 that have the same base but different wattage rating.

Also possible the socket or bulb base is making poor electrical contact - I once had a bulb that would randomly go out, but if I knocked on the taillamp assembly, it would light up. I ended up cleaning the socket AND replacing the bulb, as the bulb cost under 2 dollars - problem solved.

After you turn the headlights on, the taillamps are also turned on. I would speculate that one or more of the taillamps warms up after 5-10 minutes of driving/usage and no longer creates the out-of-spec condition after the warmup.

So the question is what takes more time+money, 1) replacing all brake-related taillamp bulbs including the center stop lamp with the correct part numbers from your local Toyota or Lexus dealer, or 2) taking apart the luggage room fusebox/ECU, figuring out the circuit schematic, then figuring out a way to bypass the detection circuit(s), and if you want to bypass for just the stop lamps, or for all rear taillights, or for any "taillamp failure" message, which also includes the tiny bulbs in the front headlights.

I would start with option 1, as these bulbs are dirt cheap from the dealer and are easy to replace via the access flaps in the trunk.

(previous taillight failure discussion at https://www.clublexus.com/forums/ls-...re-signal.html)

RomanTPA

Replaced every single bulb with Lexus bulbs and the problem is still there. $60 wasted for no reason.

Duck05

Our '01 has had the "tail light failure" warning intermittently now for several years. None of the bulbs are out but one of the sockets may have a short as a few hard "raps" on the tail light and trunk lid results in the light going out.....

Taking apart the light assemblies and inspecting the bulbs and connectors have not revealed the source and after putting everything back together there are a few months of relief. It is bothersome but not enough to attempt to disable the display.

Could be a faulty ECU but those can be expensive and not always the source.......

Keep us posted .......

Tom57

When the warning lights on the dash, check which light bulb is not lighting. Then focus on that light string working from the bulb & socket backward to the ECU. Also, the brake light switch itself could be faulty. I replaced it on my '01.

Edit: Suggest you PM "Yamae" ... he is an electrical engineering consultant to Toyota/Lexus.

StanVanDam

Sorry to hear. At least that rules out incorrect or failing bulbs, and now you have more supporting evidence that you might need to buy a new ECU (as opposed to buying a new ECU first and finding out it was a cheap bulb/socket/wire/brake light switch).

I've attached an example of a Lexus light failure detection circuit - this diagram is NOT specifically for an LS430, but it is for an unspecified Lexus/Toyota vehicle. Might help you figure out the circuit schematic of the luggage room junction box ECU. Then you can measure current draws, voltages, and/or resistances at each input (depending on how the detection circuit works) to try to pinpoint the problem.

Or you can skip pinpointing the problem and just figure out how to disable the light failure circuitry for the brake lights or in its entirety. Or install a new ECU and hope that fixes it.

If you decide to take apart the junction box/ECU, post some pictures, maybe someone will see something that can be helpful.

It also wouldn't hurt to ask a head tech at a local Lexus/Toyota dealership for other ideas - I asked once in casual conversation, he did not know the specifics of the circuit but was fairly certain it was not in a separate module as other Lexus/Toyota vehicles had utilized in the past.

Brewmyown

Here's some wiring diagram and routing info

wise2k

I'm in the same boat having had that message for the past year I've owned the car; I've been trying to learn to live with it but it's just difficult (and, honestly, embarrassing) with that BIG RED TRIANGLE with an EXCLAMATION MARK in addition to the constant textual message already displaying (not enough?!).
I don't get why they coupled those two for that kind of fault. I understand and appreciate the importance of taillights functioning properly but I still think they could have saved that BIG RED TRIANGLE for things like ABS malfunction, engine malfunction (like I just replaced one of the VVTi oil solenoids), etc. Oh well, just a rant!

Brewmyown

I had the warning light pop up a handful of times over the course of about 2 months and every time it happened, I found a bulb I didn't know existed. There are a couple small bulbs in the headlight assembly when I was changing the ballasts I didn't even know were out because I never got any error light or anything like that?

I'll keep browsing my repair manual to see if I can find anything of interest regarding this issue.

Brewmyown

Here are some more wiring diagrams that may help track it down.

Brewmyown

He's not talking about that warning light. When you have a tail alight build out, as soon as you put the car in gear it's supposed to "ding" and then you see a tail lamp failure warning where it shows low washer fluid in the picture above. Then I believe there's a red triangle or exclamation point that illuminates. I have had it happen a few times and it's always been a bulb somewhere.

Brewmyown

This is the warning message he's referring to.

wise2k

Very interesting information. Mine is normal/clear instrument panel during the day, but as soon as it gets dark and lights on, BAM!!! BIG RED TRIANGLE with EXCLAMATION MARK...AND...TAILLAMP FAILURE message. I have replaced each and every light bulb with the right bulbs (to my knowledge from this forum) including the tag-plate lights, but still, no difference.

So, from what you said above, are you suggesting that the "TAILLAMP FAILURE" message is generic to include light bulbs at the front of the car..? That would be something. Let me know because all I know right now is that both my headlights work and my DRL work.

RomanTPA

According to FSM in post #13, "TAILLAMP FAILURE" message only covers the rear lights.