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This is a 2006 TL automatic and I am having an issue with the tail lights staying on when the car is off, all lights are off and car is locked. I checked the brake switch and rubber grommet and all is well and functioning there. These are the tail lights. I disconnected the battery as to not drain it but I need to try and get this issue resolved. Any help would be greatly appreciated!! Thanks in advance
1. Tail lights or brake lights? It might be confusing, but LED taillights are driven by two wires/two circuits.
Simply put, if taillights would stay on:
- they would be dimmer than brake lights
- middle/3rd brake lights won't be on
- side markers should be on
If brake lights would stay on,
- they would be as bright as it gets
- middle/3rd brake light should be on
- side markers shouldn't be on
2. Can you do some basic troubleshooting if you have circuit diagram? Do you have multimeter or at least test light?
3. What you mean that you checked the brake switch and it's functioning? Either test it or don't assume anything. It might be broken on the inside.
4. Take a look at those and let us know:
Try to answer all of my questions, preferably with number in front so we avoid any confusion.
Hey Peter6 thanks for the reply.
1. I believe it is the tail lights. When I hit the brake pedal the led lights get brighter as well as the third light illuminates. Unfortunately there are no other marker lights on just the two dimly lit rear led lights on either side of the trunk.
2. I do have a multimeter and could do some troubleshooting.
3. As for testing the brake switch I just visually inspected the condition of the switch and rubber or plastic grommet/spacer to ensure it was intact. As I push the brake pedal the switch closes and opens as it should and the brake lights then illuminate brighter/ third light illuminates.
4. As for the diagrams I’m gonna print them out and I believe should be able to follow them easily enough. Is there a separate relay inside the relay control module for just the tail lights they may have gone bad? Are there any ways to test this?
Thanks again for getting back to me I hope I was able to answer your questions.
Iggy
Also forgot to mention this is only occurring at night the lights will be off and fine durning the day then at night they will be on. Sorry meant to include that before.
Thabks
5. If you take a look at the first photo, there should be 3 wires going to the each taillight. Pick one side and measure voltage from some good ground (other than one in the connector)(maybe something in the trunk? under the cover) to each wire.
- if you have something at red/black wire, we know that there is a problem with tail light wire
- if you have something at white/black wire, we know that there is a problem with brake light wire
6. Try eliminating fuses/relays until tail lights turn off. For example, take fuse #4 from under hood to eliminate power supply to tail lights and check if they went out. Remember to check any colors/numbers of wires/fuses with your car, as diagrams are sometimes different.
7. I would try to disconnect (no idea how hard it is) brake light switch. What if it doesn't open fully, and passes some current? Won't hurt to try.
Originally Posted by Iggycurry10
Also forgot to mention this is only occurring at night the lights will be off and fine durning the day then at night they will be on. Sorry meant to include that before.
Thabks
8. Now it's getting weird. Are you sure that they are off during the day? Maybe they are very dim and you just can't see?
Because the only way for lights to "know" if it's bright, is by using light sensor (used for "Auto" mode for the headlights) but there is no real connection between the two.
To the OP, since you say it is only the taillights that are on...this would probably be related to the brake light circuit and not the taillight circuit. If it were related to the taillight circuit, in theory the side marker lights would be impacted as well. My bet is that the brake light switch is failing. Get up under the dash and un-clip the harness on the switch to test.
Am I the only one that is perplexed by the wiring schematic of the 3rd brake light?
What is the symbol on the far left?
What is the point of the two diodes? From this drawing, they would always be bypassed anyways since the 12V+ from the switch feeds to the unknown item on the left, direct to the LEDs, and then also to the diodes.
Am I the only one that is perplexed by the wiring schematic of the 3rd brake light?
What is the symbol on the far left?
What is the point of the two diodes? From this drawing, they would always be bypassed anyways since the 12V+ from the switch feeds to the unknown item on the left, direct to the LEDs, and then also to the diodes.
I didn't see it before, but you are right. Guess they must made a mistake and they put one extra 'dot' somewhere or something. Anyways, there is no point putting diodes in series with LEDs anyways, and that 'Z' symbol...
There is the 'same' circuit from identifix:
Guess two diodes are for redundancy or they use really low current diodes and they put two to compensate.
And one from alldata:
This one doesn't have any diodes at all, but it lists capacitor for 04-05 models... to reduce flickering?
So maybe that 'z' from first schematic was supposed to be a capacitor or some other kind of filter. Because what else they would connect parallel to diodes?
My guess is the first diagram, the 12V line that goes straight down shouldn't exist. If you remove that, it roughly lines up with the alldata diagram. My guess is the odd Z box is a capacitor and ferrite bead together. I do find it interesting that is says '04 and '05 only.
Is there some sort of daylight sensor for the lights that turns them on at dusk? Could that have failed? He says only happens at night.
It's not possible:
There is a light sensor, which is used when you switch lights to "Auto" but it feeds into the computer and has no direct connection to the lights.
Even when you put your fog lights or headlights ON, the switch don't have direct contact. If feeds into it's own control unit, and then into the MICU. (that dashed line on the schematic is a communication wire)
- Moreover, if computer would go bad, it can control the lights ONLY by feeding power to the relays. That means that either all lights on 'taillight' circuit would work or not. That includes side markers and front markers, and OP stated that they are not ON.
- The brake lights have no real connection to the computer, it's simply mechanical switch next to brake pedal and that's it. The only connection is a 'sense' wire so car's computer know that brake pedal is pressed, for example to release the shifter lock.
I guess computer can go bad and back feed into that circuit, but most likely bunch of stuff wouldn't work, and 3rd/middle brake light would illuminate as well.
For now I stay with Jackass - maybe the switch doesn't open all the way. But we won't know that until OP measures voltage at taillight connector or disconnects that switch.
I'm also pretty sure that taillights are very dim - just enough to see them when it's dark, but not enough to see them when it's bright. Of course there is a way to check it, but it's on OP.
I'm having the same issue with my 3G TL. My taillights & side markers stay on when the car is off and when it's locked. in the mean while i've been pulling the ACC Backup fuse when it's off and locked. I'm gonna try and test the circuits for the taillights, side markers and parking lights.
If there is an issue with the wires. 1. how would i know? 2. how/ what can i do to fix the issue? 3. I don't have a multimeter i only have a voltage tester (w/ the light bulb) 4. i've pulled ever fuse in the fuse box under the hood and the lights continued to run, except for when i pull the ACC Back up fuse. 5. Is there a tail light fuse/relay that could be causing the issue? 6. Is i possible that the issue is my computer or something?
Are you sure that it's fuse #5? Under hood or inside under-dash fuse? On the schematics the fuse going to taillights/sidemarkers is #4 under-hood, so get me all the info so I can make sure you have proper schematic to look at.
Which year/model you have/type-s or not/mt or at? Are you sure that it's fuse #5? On the schematics the fuse going to taillights/sidemarkers is #4, so get me all the info so I can make sure you have proper schematic to look at.
It's a 2006 TL (Not type-s) Automatic transmission.
The fuse number isn't #5 it's labeled a 40 AMP "Backup, ACC" and its under the hood
It's a 2006 TL (Not type-s) Automatic transmission.
The fuse number isn't #5 it's labeled a 40 AMP "Backup, ACC" and its under the hood
Originally Posted by williamv_ovoxo
. . . pull the ACC Back up fuse. 5. Is there a tail . . .
I don't think I was drunk yesterday... guess I was reading too fast. Or I'm getting blind and I don't see dots anymore. My bad.
I have some more time, so I will try to answer your questions.
Originally Posted by williamv_ovoxo
If there is an issue with the wires. 1. how would i know?
2. how/ what can i do to fix the issue?
3. I don't have a multimeter i only have a voltage tester (w/ the light bulb)
4. i've pulled ever fuse in the fuse box under the hood and the lights continued to run, except for when i pull the ACC Back up fuse.
5. Is there a tail light fuse/relay that could be causing the issue?
6. Is i possible that the issue is my computer or something?
Please and thank you!
1. When fuse for taillights is removed, but taillights stay on anyways, it must mean that taillights are getting power through some other way. It might be two broken wires, but the only way to find out is... to find broken wires.
2. Depends what's wrong.
3. That is fine as long as you don't probe 'control signals' from the computer. Probing power/ground wires with it is actually better than using just the multimeter.
4. Rest of the post addresses that
5. There is a relay, but it's 'integrated' into the fusebox. That means, that if it went bad the only way is to replace entire under-hood fusebox. I don't know if anybody tried to open it and replace single relay. It might be all epoxied to prevent poking around.
6. Computer gives power to the relay's coil... so yes. But I would say it's unlikely.
7. So it's fuse #15, right? It goes to under-dash (on the inside) fuses #5, 6, 7, 8, 9.
So put under-hood #15 back and check if pulling any of those makes the lights to go out.
Also pull out under-hood fuse #7 and under-hood #4.
Just to clarify, the way you do it is you put all fuses back, and take them out one at the time. Every time verify if taillights are still ON. It they go out let us know. Under-hood #4 is main fuse that feeds the relay and the taillights. Taking it out should disable them. If that is not the case, lights must be getting power some other way.
8. Are any of the lights weirdly brighter or dimmer than the rest? For example one of front turn signals/marker lights - is one dimmer/brighter than the other?
I'm having the same issue with my 3G TL. My taillights & side markers stay on when the car is off and when it's locked. in the mean while i've been pulling the ACC Backup fuse when it's off and locked. I'm gonna try and test the circuits for the taillights, side markers and parking lights.
If there is an issue with the wires. 1. how would i know? 2. how/ what can i do to fix the issue? 3. I don't have a multimeter i only have a voltage tester (w/ the light bulb) 4. i've pulled ever fuse in the fuse box under the hood and the lights continued to run, except for when i pull the ACC Back up fuse. 5. Is there a tail light fuse/relay that could be causing the issue? 6. Is i possible that the issue is my computer or something?
Please and thank you!
So I have a buddy that just bought a 06 base, has the same problem. Tail lights, license plate light, and side markers all on. Fuse 4 in the hood keeps blowing, but before that problem the only way to turn them off at the time was pulling the radio fuse. Now when he throws a fuse in it blows leaving him with out parking lights just break lights and reverse lights. Any help would be nice. Semi old thread but only one that semi matched his problem.
02-09-2019, 01:58 PM
