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Hello, recently bought my 1996 LS400, today I replaced my cracked rear light and I immediately noticed the light bulb warning light was on the dashboard. I didn’t touch the bulbs and harness in the process.
I then found the rear right upper brake light has one filament broken, so I replaced it with the bulb that came with the replacing light and it lit on when turn the lights on but won’t brighten when I depress the brake pedal. The warning light is still on. I’m sure that the bulbs and wires that connect to the clip connector in the trunk both work, so the issue is in the wiring itself, which could be a nightmare. The 10A rear light fuse is also intact, please help, thanks! The rear right upper light is on After depressing the brake, it stays the same brightness
Hello, recently bought my 1996 LS400, today I replaced my cracked rear light and I immediately noticed the light bulb warning light was on the dashboard. I didn’t touch the bulbs and harness in the process.
I then found the rear right upper brake light has one filament broken, so I replaced it with the bulb that came with the replacing light and it lit on when turn the lights on but won’t brighten when I depress the brake pedal. The warning light is still on. I’m sure that the bulbs and wires that connect to the clip connector in the trunk both work, so the issue is in the wiring itself, which could be a nightmare. The 10A rear light fuse is also intact, please help, thanks! The rear right upper light is on After depressing the brake, it stays the same brightness
First thing to do: open that right rear light hosing, and inspect CAREFULLY all the contacts and screws in there. Look for signs of poor contact, corrosion, melting plastic etc.
I had them melt on me more than once (twice maybe three times, don't remember, and currently one of the screws melted the plastic around it so it doesn't work no matter what). It seems to happen a lot - screw gets a little loose, or bulb does and then it heats up, and melts the plastic just enough to cause a short or whatever, and you get a weird problem like that.
Then, if you are absolutely positively certain that that's not the problem, continue checking other things, like the harness that is going along the left hinge of your trunk, and so on. But I am willing to bet that its a contact in the light housing itself. Just go over it carefully.
ps. if it's not that, then it may be the rear light module, in your trunk, next to the alarm on the left side.
First thing to do: open that right rear light hosing, and inspect CAREFULLY all the contacts and screws in there. Look for signs of poor contact, corrosion, melting plastic etc.
I had them melt on me more than once (twice maybe three times, don't remember, and currently one of the screws melted the plastic around it so it doesn't work no matter what). It seems to happen a lot - screw gets a little loose, or bulb does and then it heats up, and melts the plastic just enough to cause a short or whatever, and you get a weird problem like that.
Then, if you are absolutely positively certain that that's not the problem, continue checking other things, like the harness that is going along the left hinge of your trunk, and so on. But I am willing to bet that its a contact in the light housing itself. Just go over it carefully.
ps. if it's not that, then it may be the rear light module, in your trunk, next to the alarm on the left side.
Thanks for you detailed information. I’m very sure that the housing and contacts are good, I even test two more sets of the bulb harnesses, and they all had the same issue.
Light housing removed, two tails lights on
Pressing brake, only the bulb on the right brightened
I’ll check the remaining harness and the light module that you mentioned.
Hello, recently bought my 1996 LS400, today I replaced my cracked rear light and I immediately noticed the light bulb warning light was on the dashboard. I didn’t touch the bulbs and harness in the process.
I then found the rear right upper brake light has one filament broken, so I replaced it with the bulb that came with the replacing light and it lit on when turn the lights on but won’t brighten when I depress the brake pedal. The warning light is still on. I’m sure that the bulbs and wires that connect to the clip connector in the trunk both work, so the issue is in the wiring itself, which could be a nightmare. The 10A rear light fuse is also intact, please help, thanks!
I'd check the tail light failure sensor located in the left side of the trunk. I worry that there is/are burnt trace(s). The photo below shows only cracked soldering points. But other than those soldering issues, it is the often case that traces that carry big current are tend to burn out. There are totally 8 brake related bulbs and the inrush current exceeds 40A or more when the brake pedal is pushed. Within 3 seconds, the current goes down to 13A or so but still its not a small current and repetition of the braking damages soldering points and traces. I'd say Toyota should had designed the board more robust and trouble free.
BTW, what yamae is saying about is the module I refered to. Mine threw me in for a loop because it locked my transmission thinking all my rear lights including break lights were out (and they were!), but nothing was broken except the stupid module!
And then when I opened it - nothing. Inside was pristine, and looking as good as new. But when I bypassed it, everything worked fine. Angry that I spent so much time trying to diagnose that problem I don't intend on putting it back in. Ever. I can check my own brake lights.
Are you absolutely sure that the bulb is good? You mentioned you took that bulb from the replacement housing, so it's used. Easy way to check is just switch the bulbs in the upper and lower sockets. Or take the good bulb from the left light and try in the right. Was the dash warning light on before you switched the housing?
BTW, what yamae is saying about is the module I refered to. Mine threw me in for a loop because it locked my transmission thinking all my rear lights including break lights were out (and they were!), but nothing was broken except the stupid module!
And then when I opened it - nothing. Inside was pristine, and looking as good as new. But when I bypassed it, everything worked fine. Angry that I spent so much time trying to diagnose that problem I don't intend on putting it back in. Ever. I can check my own brake lights.
It needs to be a simpler set up. I mean, I don't want my brake lights to be out, but I need my transmission to work long enough to get me home (or to the auto parts store). We are lucky I guess—Ford, GM, and Toyota all manufacture vehicles that have intermittent headlight outages. Who knows, maybe they all do. One minute you’re driving along and poof—total darkness. I think it only causes one headlight to go out on the Toyota—which is heat related, not module related. That is one of the reasons I got rid of my 03 Towncar. The lighting modules were defective and always on back order.
I'd check the tail light failure sensor located in the left side of the trunk. I worry that there is/are burnt trace(s). The photo below shows only cracked soldering points. But other than those soldering issues, it is the often case that traces that carry big current are tend to burn out. There are totally 8 brake related bulbs and the inrush current exceeds 40A or more when the brake pedal is pushed. Within 3 seconds, the current goes down to 13A or so but still its not a small current and repetition of the braking damages soldering points and traces. I'd say Toyota should had designed the board more robust and trouble free.
Thanks a lot for the explanation, I just ordered a module from eBay which costs only 12 dollars. Let’s see if it fixes the issue
BTW, what yamae is saying about is the module I refered to. Mine threw me in for a loop because it locked my transmission thinking all my rear lights including break lights were out (and they were!), but nothing was broken except the stupid module!
And then when I opened it - nothing. Inside was pristine, and looking as good as new. But when I bypassed it, everything worked fine. Angry that I spent so much time trying to diagnose that problem I don't intend on putting it back in. Ever. I can check my own brake lights.
Good to know, thanks. I just ordered one from eBay for only 12 dollars, not bothering checking inside, maybe I’ll find a bad contact maybe it’s pristine as yours.
Are you absolutely sure that the bulb is good? You mentioned you took that bulb from the replacement housing, so it's used. Easy way to check is just switch the bulbs in the upper and lower sockets. Or take the good bulb from the left light and try in the right. Was the dash warning light on before you switched the housing?
I’m very sure that the bulb is good, visually inspected the filaments and also tried on 3 bulbs with same results. The warning light was off before switching the house and I didn’t mess up the wiring or bulbs at all in the process of switching, very weird.
Status report, replaced the lamp failure module and had the exactly same result, the circuits in the original module looks brand new. What other cause could it be?
Just recalled that the warning light on the dashboard turned on for a while on the way back home from the seller. I didn't know what it is and it went away soon.
06-21-19, 06:29 PM
1996 LS400 brake light issue
