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- 5 August 2023
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Rear brake light Warning
- Thread starter catalystrx
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- @vansxtc
There are several things that can be the culprit. Wire harness itself is pretty low on the list.
If the "BRAKE LAMP" warning on the safety indicator is intermittently turning on and off, do you have any other symptoms of things being "odd" in respect to how electrical components in the trunk are functioning? Most notable, does the power antenna still extend and retract at normal speed or is it slow/"jerky"? Also, are you running the incandescent bulbs (standard) or do you have LED brake lights installed?
How I would go about this:
1) Familiarize yourself with the information and troubleshooting regarding this indication in the Factory Service Manual. It will be in Chapter 23.
2) Check the brake lights themselves - are any burned out? Do any have corrosion on the base?
3) Look at the condition of the bulb sockets while checking the bulbs. Since bulbs are cheap, I would just put a new set of bulbs (all 4 of them) in while I've got the tail lights accessed.
4) Check the connectors (I would recommend disconnecting the various connectors in the trunk (there are ones at the tail lights themselves, and then there is a large connector in the front left corner of the trunk behind the lining), clean them with some QD Electronic Cleaner spray then make them back up.
5) Have somebody follow you and see if the tail lights/brake lights are flickering as the car goes over bumps. And if they note they are flickering, is the "BRAKE LAMP" warning also flickering on/off?
6) Check the trunk ground (G551) - it is on the left side (you need to remove the trunk side liner that has the light in it) and it is by the power antenna motor. If that is loose, then you could get flickering lights, sluggish/"jerky" antenna operation, and the "BRAKE LAMP" warning on.
Now, if the tail light/brake light bulbs are good, and there isn't any noticeable issues with the wire harness, then do the troubleshooting of the lamp failure detection modules (again, in Chapter 23 of the NSX Factory Service Manaul)
Finally, keep in mind that the "BRAKE LAMP" warning coming on when the bulbs and detection modules are good is a "leading indicator" for leaking capacitors in the instrument cluster itself. If everything checks out, I recommend removing the instrument cluster and opening it up to see if there is any leaking capacitors in the instrument cluster. Instrument Cluster removal is detailed in Chapter 23 as well. If you are careful and use the tilt/telescope features of the steering column to your advantage, you can remove the instrument cluster without having to remove the steering column covers like the removal procedure calls for. Even if you don't find any significant issues with the capacitors, I recommend boxing up the instrument cluster and sending it to Brian Kiehnau at nsxe-repair and have him replace the capacitors with new, modern capacitors. Leaking capacitors in the instrument cluster have been linked to at least two or three electrical fires that have causes significant damage (in one case, I think the affected NSX was a total loss)
But don't think the system "fixed itself" if the indication was on and suddnely turns off by itself.
If the "BRAKE LAMP" warning on the safety indicator is intermittently turning on and off, do you have any other symptoms of things being "odd" in respect to how electrical components in the trunk are functioning? Most notable, does the power antenna still extend and retract at normal speed or is it slow/"jerky"? Also, are you running the incandescent bulbs (standard) or do you have LED brake lights installed?
How I would go about this:
1) Familiarize yourself with the information and troubleshooting regarding this indication in the Factory Service Manual. It will be in Chapter 23.
2) Check the brake lights themselves - are any burned out? Do any have corrosion on the base?
3) Look at the condition of the bulb sockets while checking the bulbs. Since bulbs are cheap, I would just put a new set of bulbs (all 4 of them) in while I've got the tail lights accessed.
4) Check the connectors (I would recommend disconnecting the various connectors in the trunk (there are ones at the tail lights themselves, and then there is a large connector in the front left corner of the trunk behind the lining), clean them with some QD Electronic Cleaner spray then make them back up.
5) Have somebody follow you and see if the tail lights/brake lights are flickering as the car goes over bumps. And if they note they are flickering, is the "BRAKE LAMP" warning also flickering on/off?
6) Check the trunk ground (G551) - it is on the left side (you need to remove the trunk side liner that has the light in it) and it is by the power antenna motor. If that is loose, then you could get flickering lights, sluggish/"jerky" antenna operation, and the "BRAKE LAMP" warning on.
Now, if the tail light/brake light bulbs are good, and there isn't any noticeable issues with the wire harness, then do the troubleshooting of the lamp failure detection modules (again, in Chapter 23 of the NSX Factory Service Manaul)
Finally, keep in mind that the "BRAKE LAMP" warning coming on when the bulbs and detection modules are good is a "leading indicator" for leaking capacitors in the instrument cluster itself. If everything checks out, I recommend removing the instrument cluster and opening it up to see if there is any leaking capacitors in the instrument cluster. Instrument Cluster removal is detailed in Chapter 23 as well. If you are careful and use the tilt/telescope features of the steering column to your advantage, you can remove the instrument cluster without having to remove the steering column covers like the removal procedure calls for. Even if you don't find any significant issues with the capacitors, I recommend boxing up the instrument cluster and sending it to Brian Kiehnau at nsxe-repair and have him replace the capacitors with new, modern capacitors. Leaking capacitors in the instrument cluster have been linked to at least two or three electrical fires that have causes significant damage (in one case, I think the affected NSX was a total loss)
But don't think the system "fixed itself" if the indication was on and suddnely turns off by itself.
And don't forget to check the amount of brake fluid you have in the master cylinder reservoir. That must be full to the top or you will get the Brake Lamp warning light also.
NOOOOOOO!!!!!! That is a different light entirely. The "BRAKE" light will come on in three situations: 1) Parking Brake is Applied, 2) Brake Master Cylinder level is low, and 3) for a lamp check when starting the car (if the MC fluid level is normal and the parking brake is not applied when the car is first started, it gets a lamp check as well since it is a critical warning regarding functionality of the hydraulic brakes...most people, if they start the car with the parking brake engaged, never see the lamp check function since the light is already on and the bulb is, effectively, checked.
The "BRAKE LAMP" warning on the safety indicator (small car shaped LED display on the bottom of the instrument cluster between the tachometer and speedometer only indicates if one (or more) of the 4 brake light bulbs in the two lower tail lights is burnt out. It does not monitor the spoiler/wing mounted LED 3rd brake light.
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+1 on the cluster to @Briank unless you find very clear evidence that it was a bad bulb, loose bulb, or problematic ground connection.
The brake bulb out indicator turning on and off while driving is not a common symptom. Could you clarify what you meant by "on and off again brake lamp warning light"? Do you mean that it sometimes comes on when you are driving (and then stays on), or that it comes on and goes off intermittently while you are driving, or something else entirely? Is it related to brake pedal application?
I believe if a brake bulb is out, the brake light warning lamp should still turn off after the self test when you turn the ignition on if the brake pedal is not depressed, then be illuminated when you press the brake pedal, and then stay on even after the brake pedal is released. If it comes on before the brake pedal is pressed, or stays on after the self-test completes without the brake pedal being pressed, look at the gauge cluster. The reed switches that trigger the bulb-out indicator are "powered" by the brake light wiring (delta between brake light wire and series reed switch output), so there would be no way for the system to know you have a brake bulb out until the brake pedal is pushed. Thus a bulb-out indicator illuminating without brake pedal application suggests a cluster capacitor problem must be ruled out.
The brake bulb out indicator turning on and off while driving is not a common symptom. Could you clarify what you meant by "on and off again brake lamp warning light"? Do you mean that it sometimes comes on when you are driving (and then stays on), or that it comes on and goes off intermittently while you are driving, or something else entirely? Is it related to brake pedal application?
I believe if a brake bulb is out, the brake light warning lamp should still turn off after the self test when you turn the ignition on if the brake pedal is not depressed, then be illuminated when you press the brake pedal, and then stay on even after the brake pedal is released. If it comes on before the brake pedal is pressed, or stays on after the self-test completes without the brake pedal being pressed, look at the gauge cluster. The reed switches that trigger the bulb-out indicator are "powered" by the brake light wiring (delta between brake light wire and series reed switch output), so there would be no way for the system to know you have a brake bulb out until the brake pedal is pushed. Thus a bulb-out indicator illuminating without brake pedal application suggests a cluster capacitor problem must be ruled out.
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- Joined
- 5 August 2023
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- 2
Thanks running some driving tests this weekend and will provide feedback
Kevin
Kevin
@Wild Turkey, would you mind clarifying your last sentence, "Thus a bulb-out indicator illuminating without brake pedal application suggests a cluster capacitor problem must be ruled out." Are you saying that if the BRAKE LAMP indicator stays on all the time, it's likely a cluster problem? Or do you mean by "must be ruled out" that it's not a cluster problem? My brake lamp indicator stays on all the time, and I checked the four bulbs in the back and all appear to be good.
@rustymufflers , need to clarify "appear to be good". Does that mean that you've had someone looking while you pressed the brake pedal and all 4 brake lights go on and off as appropriate when the brake pedal is pressed, checked both with and without the running lights on, not that you've removed the bulbs and tested them externally? The indicator can also come on if the bulbs are loose in the housings or if connectors are corroded or loose, or a wiring problem; hence the suggestion to have a following driver look for aberations. If the brake lights work properly and the BRAKE LAMP indicator is on, it is very likely you have a capacitor problem with your gauge cluster.
Sorry for the terminology - "must be ruled out" is a term that combines "is very likely" with "is very serious" and you must check carefully if it is the case and not go any further until you are sure it is not the case. @Heineken & @Briank are more expert, but my understanding is that the BRAKE LAMP indicator normally comes on for a couple of seconds and then goes out as part of the initial self test. If you have a blown brake bulb, the BRAKE LAMP indicator will illuminate when you subsequently press the brake pedal, or if you still had the brake pedal pressed from starting, it will remain lit after the rest of that cluster has completed the lamp test. Thus to test it, you keep your foot off the brake pedal and keep the car still with the e-brake while starting. Then press the brake pedal to see if the BRAKE LAMP indicator comes on
If you start the car and the BRAKE LAMP remains lit after the self test, without pressing the brake pedal, or comes on again before the brake pedal has been pressed, it is most likely a capacitor problem with the dashboard.
Also, if you have LED's installed and the sensor bypassed, and the BRAKE LAMP indicator comes on, it's also very likely to be the cluster capacitor problem that could lead to a fire.
Hope that clarifies.
Sorry for the terminology - "must be ruled out" is a term that combines "is very likely" with "is very serious" and you must check carefully if it is the case and not go any further until you are sure it is not the case. @Heineken & @Briank are more expert, but my understanding is that the BRAKE LAMP indicator normally comes on for a couple of seconds and then goes out as part of the initial self test. If you have a blown brake bulb, the BRAKE LAMP indicator will illuminate when you subsequently press the brake pedal, or if you still had the brake pedal pressed from starting, it will remain lit after the rest of that cluster has completed the lamp test. Thus to test it, you keep your foot off the brake pedal and keep the car still with the e-brake while starting. Then press the brake pedal to see if the BRAKE LAMP indicator comes on
If you start the car and the BRAKE LAMP remains lit after the self test, without pressing the brake pedal, or comes on again before the brake pedal has been pressed, it is most likely a capacitor problem with the dashboard.
Also, if you have LED's installed and the sensor bypassed, and the BRAKE LAMP indicator comes on, it's also very likely to be the cluster capacitor problem that could lead to a fire.
Hope that clarifies.
Thanks @Wild Turkey for your quick (and thorough) reply! My brake lamp indicator came on today and it stays on the whole time, independent of the brake pedal. I had someone press the brake pedal for me and verified that all four lights in back work fine (as does the wing, but my understanding is the light bar on the wing is unrelated). I pulled out all four bulbs just to make sure they all look good and are seated correctly, but it seems like that's all irrelevant if the indicator stays on the whole time. Damn.
I was actually just reinstalling my repaired amps (from Brian K) and radio and hoping that I'd finally drive a fully functional NSX for the first time. Guess I have to pull the instrument cluster and send it to Brian now.
I was actually just reinstalling my repaired amps (from Brian K) and radio and hoping that I'd finally drive a fully functional NSX for the first time. Guess I have to pull the instrument cluster and send it to Brian now.
Gave this some more thought. Although a gauge cluster capacitor problem is a strong possibility and MUST be investigated thoroughly because it can cause a fire, there are a few other things to consider in the diagnosis. Review the threads I've listed below before going ahead:
Threads to review, especially the wiring diagrams in them:
Be sure to let us know how you work it out for others who might have a similar problem.
{Thread moved to NSX DIY}
- RIGHT BRAKE LIGHT FAILURE SENSOR failure
- LEFT BRAKE LIGHT FAILURE SENSOR failure.
- A problem with the 3rd brake light or wiring in the spoiler.
- Break in the white/green between C5 & C562, or at one of those connectors
- Break in the orange/white between C562, C534, C407, ..., or at one of those connectors.
- Bypass the sensor as many have done when they get LED tail light bulbs. (Everyone should have LED brake light bulbs for safety because they illuminate faster anyway, BTW.) If that solves your problem, it is one or both of the failure sensors, or the 3rd brake light. In that case, the cheaper and safer solution is to get LED bulbs and leave the sensor bypassed, after verifying that the 3rd brake light is working properly.
- If that doesn't solve your problem, it is the wiring breaks above or the gauge cluster.
Question: Is it reasonable not to upgrade the stock brake bulbs to LED's any more???
Update from this thread 2 years ago since the technology has really become easy, cheap, and mainstream:
www.nsxprime.com
I share the love of @DRIFTER for the look of incandescent running and brake lights, but here's a new thread to keep the other thread on its headlights topic and discuss brake light options here. (The warm look of incandescents is the reason I spend a whole day...
Update from this thread 2 years ago since the technology has really become easy, cheap, and mainstream:
How good are LED replacement brake lamp and signal lamp bulbs these days?
Bob's post got me thinking... http://www.nsxprime.com/forum/showthread.php/216155-What-brake-lamp-bulb-part-is-needed How good are the LED replacement bulbs these days? I tried some maybe >5yrs ago and they were terrible. Light output was low and quite directional so it didn't really "fill"...
www.nsxprime.com
I share the love of @DRIFTER for the look of incandescent running and brake lights, but here's a new thread to keep the other thread on its headlights topic and discuss brake light options here. (The warm look of incandescents is the reason I spend a whole day...
Threads to review, especially the wiring diagrams in them:
Be sure to let us know how you work it out for others who might have a similar problem.
{Thread moved to NSX DIY}
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All right, looks like I have some work cut out for me. Unless you or anyone reading this disagrees, it seems like I should get the gauge cluster out and have it serviced regardless, since it's a matter of when, not if. My main hesitation in the past was getting that damn knee bolster off as I don't know exactly which direction to pull to get them unclipped at the top. If I can manage that, the rest looks doable and I can go poking around the wiring and light failure sensors while I wait for the gauge cluster to be repaired.
Does any one know how the top part of panel 77210-SL0-A01ZA (part #9 shown here) is attached? I can see that the bottom two tabs are screwed in place (my tabs broke off) but can't figure out how to remove the panel. I'm trying to repair or replace it. The covering is coming off, too, so I'd like to work on it in front of me rather than contorted upside down underneath the steering column. 
Thanks in advance for any pointers anyone can provide.
Thanks in advance for any pointers anyone can provide.But I'd also bypass the bulb out sensor (Post 25 as referenced above) before you do, as a diagnostic step, while the gauge cluster is still present. Rule out problems with the BULB OUT SENSORS or 3rd brake light - it's always good to be more confident in your diagnosis.
Very good thought. Thank you @Wild Turkey . I just shorted those pins and confirmed the indicator light stays on.
Figured I'd follow up on this in case anyone else encounters the same thing. I just got my instrument panel back from Brian at nsxe-repair.com, installed it, and the brake lamp indicator is now off, so it looks like it's fixed!
I have the same issue: since I removed the tail lights (to get rid of moisture), the brake lamp warning intermittently comes on.... but the brake lamps do work (checked more than once by bystanders)
Will read through the thread and see if I - being not that technical at all - can maybe resolve the issue
Will read through the thread and see if I - being not that technical at all - can maybe resolve the issue
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