Taillights not turning off and flickering
11-20-23, 09:44 PM
#31
Instructor
Thread Starter
@AJLex19 so the saga continues sort of.... I had started to put together a post a bit over a week ago but then....
Since I was leaving town I simply disconnected the negative battery terminal and left it that way for the 5 days I was gone. The day after I got back (Tuesday) I reconnected the negative terminal and the lights were off. Yay!!!!
Drove the car a couple of days (Wed, Thur, and maybe Friday). No issues at all, lights came on fine on the auto setting, lights turned off normally when I got home and locked the car, etc.... Everything seemed to work as expected. Figured that either something reset or that moisture was in somewhere, took a couple days to travel to where it made contact (hence the delay), and it had dried out. Sat, Sun, Mon did not drive the car - everything seemed fine. Monday evening a couple friends stopped by and we went to dinner (one of them drove) lights were off. Got home from dinner lights were off. Had to be - there's no way three of us missed lights being on.
Shortly after getting home there was a bit of rain and we had had some rain over weekend - not super heavy but heavier than just our usual drizzle. I watched some tv for a couple hours, started to go to bed and as I was walking toward another part of the house through the windows I see red lights on on the back of the car! %$#$*(&#)(%!##@!! This time I knew I hadn't touched the fob at all for days.
I grabbed the wrench and went out and disconnected the negative battery terminal again - it was late and raining and I wasn't go to deal with it.
Next morning I reconnected the negative battery terminal and the lights were still on. It was a bit cloudy and dreary and I needed to run a few errands and stuff so took the car figuring that the LEDs wouldn't be enough to draw down the battery if I just left them on at my stops. It was dry that day (but overcast with sun breaks) Last stop I ended up being at for about an hour and a half. The lights were on when I arrived but when I came out they seemed to be off. It was getting dark so on the drive home the auto lights turned on. Got home, the lights behaved as expected.
That was 6 days ago. I've taken the car out for a few little errands and things have worked as expected. As of tonight the lights have not turned back on. We've had a some light rain on a few days, nothing probably quite as heavy as that Monday evening after dinner when they magically turned on but even that wasn't crazy - bit heavier than our normal drizzle but not like a crazy downpour or anything.
My best guess at this point is that water is somehow involved. I've checked the trunk where I could, everything feels dry. I opened the little plugs inside the trunk to where the back of the lights are and felt around in there and it all feels dry on both sides. I have not gone as far as trying to really get all of the lining out of the trunk. It doesn't smell musty at all in the trunk at all.
I'm sort of in a holding pattern until they do it again and I can take it in. I guess on the lucky side - we're coming into the season where it will rain or drizzle most days so that will hopefully give it some time to crop back up.
Since I was leaving town I simply disconnected the negative battery terminal and left it that way for the 5 days I was gone. The day after I got back (Tuesday) I reconnected the negative terminal and the lights were off. Yay!!!!
Drove the car a couple of days (Wed, Thur, and maybe Friday). No issues at all, lights came on fine on the auto setting, lights turned off normally when I got home and locked the car, etc.... Everything seemed to work as expected. Figured that either something reset or that moisture was in somewhere, took a couple days to travel to where it made contact (hence the delay), and it had dried out. Sat, Sun, Mon did not drive the car - everything seemed fine. Monday evening a couple friends stopped by and we went to dinner (one of them drove) lights were off. Got home from dinner lights were off. Had to be - there's no way three of us missed lights being on.
Shortly after getting home there was a bit of rain and we had had some rain over weekend - not super heavy but heavier than just our usual drizzle. I watched some tv for a couple hours, started to go to bed and as I was walking toward another part of the house through the windows I see red lights on on the back of the car! %$#$*(&#)(%!##@!! This time I knew I hadn't touched the fob at all for days.
I grabbed the wrench and went out and disconnected the negative battery terminal again - it was late and raining and I wasn't go to deal with it.
Next morning I reconnected the negative battery terminal and the lights were still on. It was a bit cloudy and dreary and I needed to run a few errands and stuff so took the car figuring that the LEDs wouldn't be enough to draw down the battery if I just left them on at my stops. It was dry that day (but overcast with sun breaks) Last stop I ended up being at for about an hour and a half. The lights were on when I arrived but when I came out they seemed to be off. It was getting dark so on the drive home the auto lights turned on. Got home, the lights behaved as expected.
That was 6 days ago. I've taken the car out for a few little errands and things have worked as expected. As of tonight the lights have not turned back on. We've had a some light rain on a few days, nothing probably quite as heavy as that Monday evening after dinner when they magically turned on but even that wasn't crazy - bit heavier than our normal drizzle but not like a crazy downpour or anything.
My best guess at this point is that water is somehow involved. I've checked the trunk where I could, everything feels dry. I opened the little plugs inside the trunk to where the back of the lights are and felt around in there and it all feels dry on both sides. I have not gone as far as trying to really get all of the lining out of the trunk. It doesn't smell musty at all in the trunk at all.
I'm sort of in a holding pattern until they do it again and I can take it in. I guess on the lucky side - we're coming into the season where it will rain or drizzle most days so that will hopefully give it some time to crop back up.
11-20-23, 09:59 PM
#32
Instructor
Thread Starter
@bclexus Thanks for the comments and info. It seems to be just the tail lights (and the license plate light). Nothing is ajar, car would lock and flash just fine. Other lights would go off as expected with the timers. Tail lights are original OEM and as far as I know nothing has ever been done to them. It's not the brake lights - those come on, go off as expected when the brake pedal is depressed (on the 16+ its a whole different set of lights for break lights). Turn indicators also work as expected.- again, they're own set of amber LEDs.
Nothing has been tapped into for any aftermarket work or third party equipment. Everything is stock other than swapping the F Sport wheels out for the Lux wheels.
Flickering may not quite be the right term. They sort of were getting a little dim at times, then going to normal brightness and that sort of stopped and they just stayed the normal brightness. Its a bit hard to describe and I couldn't really get it to show on a video.
Nothing has been tapped into for any aftermarket work or third party equipment. Everything is stock other than swapping the F Sport wheels out for the Lux wheels.
Flickering may not quite be the right term. They sort of were getting a little dim at times, then going to normal brightness and that sort of stopped and they just stayed the normal brightness. Its a bit hard to describe and I couldn't really get it to show on a video.
11-21-23, 06:40 AM
#33
Lexus Test Driver
Flickering may not quite be the right term. They sort of were getting a little dim at times, then going to normal brightness and that sort of stopped and they just stayed the normal brightness. Its a bit hard to describe...
In your circumstance the upstream power source feeder device (for ON/Off) would almost certainly be either a signal fed simple relay or an IC component within a lighting control module that is dedicated for the exterior 'rear combination light assembly' or for the 'rear light assembly'. I would hope to find the problem being something as simple as a relay with an internal welded contact that unintentionally completes the circuit and is affected by either temperature or high humidity or both.
It makes me wonder if you have used water or hosed underneath the hood recently?
Last edited by bclexus; 11-21-23 at 07:02 AM. Reason: orthography
11-21-23, 08:20 AM
#35
Lexus Test Driver
Jamie, that could be...but it would have to be located upstream of the tail lights themselves because it affects both the tail lights equally (as I understand it) and not just one of the tail lights.
11-21-23, 11:27 AM
#36
Instructor
Thread Starter
@bclexus As long as I've owned the car I've never used any significant amounts of water under the hood. I probably got more water under the hood by having it up in the rain while trying to disconnect the battery terminal. I generally wipe things down under the hood with a slightly damp cloth any time I detail under the hood. On rare rare instances I have very carefully used a tiny amount of water without much pressure to rinse the inner lip where the hood and fender meet being careful not to get water anywhere else. Even that wasn't any time recent - I'm thinking I did it once a few years ago because when they detailed the car for sale that area wasn't cleaned very well. Here in the PNW we get all the tiny little doug fir needles and crap that find their way into places and will start creating compost if you don't keep things clean.
The "flicker" or "pulse" that I was seeing was something like where a wire would be making better or worse contact or like where some moisture was allowing a similar thing to happen (like what you're thinking with the resistance). I would think with things like the sensors, etc... the circuit could be designed where the circuit has power but is activated by the sensor closing that loop. Does that seem too far out there to consider? The interesting thing was that even with the light switch in the DRL OFF setting (which I would think is everything off completely) it had absolutely no effect. Also FYI - when I looked in the fuse boxes to see if I could just pull the fuse they appeared completely dry with no moisture inside.
I think @FullMetalM may have something right when talking about the circuit being energized and coming on when the the circuit is closed. By the fuse box, the rear window defroster also seems to be on that circuit as well as a couple of other things if memory serves.
@jgscott - I'm not sure if you're thinking a tail light - seems odd to me that one board in one light could make the entire set light up (and the license plate lights) but I guess its possible.
One other possible clue - although I'm not 100% sure it has any relation.... Many months before I had the battery replaced at the dealer. The car had become difficult to start on Mondays if I didn't drive it over the weekend. It was the original factory battery so it would have been pushing 7 years old so I chalked it up to just being old, not some sort of parasitic draw somewhere and I had never seen the lights turn on this way during the few months where I noticed the battery getting weaker. I highly doubt there's any relationship between the two and again, there have been no other electrical issue ever with the car.
The "flicker" or "pulse" that I was seeing was something like where a wire would be making better or worse contact or like where some moisture was allowing a similar thing to happen (like what you're thinking with the resistance). I would think with things like the sensors, etc... the circuit could be designed where the circuit has power but is activated by the sensor closing that loop. Does that seem too far out there to consider? The interesting thing was that even with the light switch in the DRL OFF setting (which I would think is everything off completely) it had absolutely no effect. Also FYI - when I looked in the fuse boxes to see if I could just pull the fuse they appeared completely dry with no moisture inside.
I think @FullMetalM may have something right when talking about the circuit being energized and coming on when the the circuit is closed. By the fuse box, the rear window defroster also seems to be on that circuit as well as a couple of other things if memory serves.
@jgscott - I'm not sure if you're thinking a tail light - seems odd to me that one board in one light could make the entire set light up (and the license plate lights) but I guess its possible.
One other possible clue - although I'm not 100% sure it has any relation.... Many months before I had the battery replaced at the dealer. The car had become difficult to start on Mondays if I didn't drive it over the weekend. It was the original factory battery so it would have been pushing 7 years old so I chalked it up to just being old, not some sort of parasitic draw somewhere and I had never seen the lights turn on this way during the few months where I noticed the battery getting weaker. I highly doubt there's any relationship between the two and again, there have been no other electrical issue ever with the car.
11-21-23, 11:28 AM
#37
Instructor
Thread Starter
Yes - it's all tail lights so that was my thought too that it was unlikely a board in one tail light unit.
11-21-23, 01:24 PM
#38
Don't have the sematic to verify the design, but I don't think two different 12 volt sources feed the normal tail lights. Yes there would be a signal for L & R, for the turns, but I doubt the normal lights on, have 2 independent voltages independent of each other from the battery distribution.
Without going into series voltage vs parallel connectivity theory. If you don't get it to the shop. Try this - unplug disconnect just one side of the lights. See what happens? If the side Not disconnected still comes on and and the license plate lights or they don't come on by themselves again. Then we have step one of dia test.
If the one you unplugged lights up still, then I would get that car far away from me and get rid of it, (run). I would be afraid that AI was taking over.
I have seen a few Alien movies where they took over the cars.
Without going into series voltage vs parallel connectivity theory. If you don't get it to the shop. Try this - unplug disconnect just one side of the lights. See what happens? If the side Not disconnected still comes on and and the license plate lights or they don't come on by themselves again. Then we have step one of dia test.
If the one you unplugged lights up still, then I would get that car far away from me and get rid of it, (run). I would be afraid that AI was taking over.
I have seen a few Alien movies where they took over the cars.
Last edited by jgscott; 11-21-23 at 01:28 PM.
11-21-23, 01:55 PM
#39
Lexus Test Driver
@LexusGSboy : One thing is absolutely certain, for the tail lights to light up (either brightly or dimly or flickering) when they shouldn't be lit up at all - the tail lights are receiving voltage - because those tail lights don't light up without voltage!
Though there are times during the day when the sun is out that it may 'appear' a car's tail lights are On (lit) when it's really just the sun shining directly on them at the right angle or the sun is being reflected onto the lens from a nearby glass window pane that just makes it 'appear' the tail lights are On when they're really not.
So, to make sure I understand this - if your car is parked in an enclosed garage when it's not being driven - are you saying that your car's tail lights are actually illuminating the darkened garage walls and ceiling in red light when this mysterious tail light problem occurs?
Or, if the car is always parked outside - are you saying at night, when it's dark outside after sunset, that your car's tail lights can be seen from ¼ mile away being lit - and it just stays that way all night long?
Though there are times during the day when the sun is out that it may 'appear' a car's tail lights are On (lit) when it's really just the sun shining directly on them at the right angle or the sun is being reflected onto the lens from a nearby glass window pane that just makes it 'appear' the tail lights are On when they're really not.
So, to make sure I understand this - if your car is parked in an enclosed garage when it's not being driven - are you saying that your car's tail lights are actually illuminating the darkened garage walls and ceiling in red light when this mysterious tail light problem occurs?
Or, if the car is always parked outside - are you saying at night, when it's dark outside after sunset, that your car's tail lights can be seen from ¼ mile away being lit - and it just stays that way all night long?
Last edited by bclexus; 11-21-23 at 05:08 PM. Reason: orthography
11-21-23, 03:36 PM
#40
Just wanted to confirm the pins for the two relevant wires.
PIn 2 from 2B green wire is the output from the relay to the taillights.
Pin 16 from 2A red wire (for post face-lift) is the input or control for the relay for the taillights.
I'd say look out for next time you wash your car to see if problem reoccurs.
PIn 2 from 2B green wire is the output from the relay to the taillights.
Pin 16 from 2A red wire (for post face-lift) is the input or control for the relay for the taillights.
I'd say look out for next time you wash your car to see if problem reoccurs.
11-21-23, 04:51 PM
#41
Lexus Test Driver
11-21-23, 05:05 PM
#42
Instructor
Thread Starter
11-21-23, 05:30 PM
#43
Lexus Test Driver
11-21-23, 05:40 PM
#44
Instructor
Thread Starter
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