Aftermarket amp or LED bulbs causing ABS light???
 

My car is at the dealer to fix suddenly appearing ABS and DSC lights. They tried to troubleshoot the reason but are unable to figure out what causes the problem.
They tried to swap the PCM and ABS module from another car but they still get "strange codes" (whatever that means).

Finally they asked an engineer from Japan to chime in and he was asking about anything aftermarket in the car that has to do with electronics. I do have an amp and LED bulbs all around.

Now they want to restore everything to stock, which would mean to take out the amp and put back the stock bulbs. I have no problem with the bulbs (even though I'm quite sure they have nothing to do with the actual issue at hand), but ripping the amp out is obviously a much bigger issue.

I simply can not see and understand what the existence of the amp and the bulbs might have with the problem. I'm thinking they are clueless and just scrambling to fault something. Does this make any sense at all?

I had this amp for over a year and the LED bulbs for about six months, with no ill effects (no lights triggered). That confirms for me that they have nothing to do with all this.

What can I do (other than bend over and take everything out)?

Is anything on the amp (groud wire/remote on/etc.) connected to something that might cause a problem? Might just try disconnecting the wires from the amp itself to see if that helps? If that's the problem, and that wire isn't connected to anything, that should take care of it (doubt that's the issue, though). Maybe a fuse went bad? Don't think the LED's would make a difference? They don't require you to re-wire anything. Sounds like hot air, especially considering how long you've had these without issue.

maybe,

https://www.rx8club.com/series-i-tech-garage-22/warning-about-dieseling-76638/

also how old is the battery???? if is the orignal 330 cca it might be on the way out making the problem worse.

beers

Interesting link... however, as i said, the amp and the bulbs were there for a long time already.

The battery was recently (less than two months ago) replaced by the dealer with the stronger version since the original failed the battery test.

I think I'll disconnect (but don't remove) the amp and see if that makes any difference, even swap out the bulbs, although I will be surprised if these things help.
What I'm afraid of is that they would want me to rip out all of the wiring that was used for the amp, even though the amp itself is not connected anymore.
Then when all of this is done and the problem still persists, it turns out everything was in vain and I have to reinstall all this stuff.

Hmmm just installed LED bulbs yesterday all the way around, and two wierd things happend since..... got the ABS/TCS lights on all the time and that night, my CarPC would not shut down as normal.... I am currently resetting the ECU via the battery unplug method. I brought up 3 codes on my sCANalyzer, one of them was the Cat, since it was removed a month ago... Today, the CarPC is shutting down normally, but the ABS lights will still not go out... I will do the steering wheel sweep here pretty soon, and since my car is on jacks, I will check the sensors too... but this is all really wierd to have happen right after installing VLEDS on the turn signals, break, reverse, front running lighs and the front driving lights. My turn signal circuit is blinking fast, even with one set of resistors on the rear signals... it looks like I will need them for the front too. ALso wonder if that has anything to do with it... Craziness..

-C

p.s. I also posted this on the Dieseling post mentioned above.

pulling the battery didn't fix the ABS/TCS lights....damn.... did the steering wheel back and forth thing too, nothing. Checked the sensors, they seem to be plugged in fine.

I did turn my wheels full right and full left (with engine off) when I installed my front turn signals and driving lights... hope I didn't mess things up then....

arrrggg

Weird..................I have the following using Vleds and haven't had any issue what-so-ever.
Courtesy lights, map lights, rear dome, footwells, side markers, trunk, license plate, and driving lights. All of which are LED's. AND.........not a resistor to be found as of yet. Still have the Stealth bulbs for front and rear turn signals.
You have a couple of differences in those turn signals........has me wondering what the hell it could be :scratchhe I say...........just replace the turn signals and maybe brake lights briefly and see if that does it.

thanks for your inputs.... I happen to be borrowing a Service Manual right now, and I have been scouring it looking for some insight... Not much mention of the TCS circuit, but tons on ABS and DSC... Also noticed tonight my cruise control arms, but will not engage... I succesully did an eccentric shaft position reset, reset the PCM, idled for many minutes etc.. cleaned the MAF, all coolant flushed, and the car is running fantastic... just wish I could track down these electronic gremlins now... although possibly not having ABS is more than just a gremlin....

-C

Try the brake lights first since it's ABS. It's all I can think of and the car could really sensitive in that area. I don't remember if you said you put resistors there or not. If you mess with the load(which you did with the LED's), then that actually could be the source.

Let's me know as I'd be interested. Good luck

Tamas.....................When you say "all the bulbs" which exactly did you switch out? As you may read below, if you did the brake lights....try them first! but then you may have to do the reset to be able to really tell.

hey Mazurfer, I think from that other thread we have now determined it is the brake light led's causing the problem... at this point I am not going to install resistors on the brake circuit though....

-C

Chamberlin and Mazurfer,

Just to be exactly - the left and right brake lights is fine on LED. It is the middle one that when change will activate the warning lights.

Understood benh- thanks

Maybe since my third brakelite is hooked up to the normal load of the pontiac spoiler, replacing my right and left caused it....point being, maybe there is a combination of rear tail light modifications that does throw the system off, regardless of what actual bulbs you replace etc... In any case, I have decided to get resistors for my rear tails and see what happens. I think my cruise control is messed up too, and I definately want that back....right now, sometimes it arms, sometimes it doesn't....as you know, the CC disengages with a tap on the brake, so this could certainly be interacting too.

thanks

-C

To add, I realized my cruise control also does not work with the lights on... you can set the cruise speed, and then pop the driving lights on and the cruise disengages...
the LED brake lights have to be the cause... I will add resistors and see what happens...

-C

Interesting...........Let me know. I figured it had to be some combonation of the brake lights and that third brake light causing all the trouble.

Yep, that turned out to be exactly the case. As long as you keep the third brake light as a filament bulb, there is no ABS light.
I think this somehow might have to do with too little resistance on the brake light circuit. The one regular bulb probably has enough resistance so the the light is not tripped, but all LED brake bulbs will cause the ABS light to come on.
If that's true, then maybe using a single load resistor together with the third brake LED light might fix the issue. Or just keep the one filament bulb :)

I believe you are probably right.

As a furthering investigation, I just happened to notice last night when I was showing my lights to a friend, that even with the all the lights off, the two tail light/brake light LEDs are still glowing faintly red! So obviously there is some weird shit going on... it's probably not enough current to run a filament style bulb even dimly, but plenty to keep these VLEDs 'awake'.... Resistor install to come...

-C

Depending on which lights/LEDs you are talking about.............what are you considering for the resistors? I was on VLEDS.com tonight poking around and some are 6 ohms at 50 watts(if I remember) or 25 ohms at ............ I can't remember.

I don't remember exactly which ones I got from VLED for the rear turn signals, but I was pissed that I specifically asked them if I needed the resistors for the front two, and they did not respond until after they shipped my whole order.... So to prevent the turn signals from hyper flashing I just went to Autozone and got some of their generic ceramic ones for $12 for the fronts.... As far as the rear tails, I think I will just do the same.... I can't remember the loading on those either... but I think we'll be OK with any of them...

hey anyone have the wire diagram??? I was discussing this with a good friend (who is also an electrical engineer) and he said he might have a fix, but we're gonna have to troubleshoot a bit.

Well finally got around to putting the LEDs back in along with installing the resistors (on the brake light circuit, not the tail light circuit), and as expected there are no problems now... except these cheesy resistors from autozone are just ceramic ones without the aluminium heatsinks and these thinks get way too hot.... the funny thing was they were drawing current when I first put them in, I had put an old 13B rotor housing on the brake pedal to hold it down, and checked the lights...then when I let go the brakes, they still stayed hot, and never cooled off...I shoulda measured the current... but anyways, as soon as I started the car, they stopped exhibiting this behavior, and have been fine since, without TCS, DSC or ABS, or cruise issues.... BUT, tonight I checked one of the resistors, and it was cool, the other hot, so I think there is a bad connection or it broke internally....interestingly, there are still no codes thrown with just the one resistor working...
Bottom line, if you use the LEDs in the tail/brake position, use resistors on the brake circuit....or do like I am going to do, and just wire in the original bulbs someplace hidden, as they seem to be easier to hide and keep away from things that melt....the cheap resistors are a pain and they have very short leads....so bye bye 12 bucks...

-C

Thanks for the update! Will keep that in mind!

Don't use a resistor
 

Just FYI, I had the same ABS problem when I put all LEDs on my brake lights. And it cost me too much in dealer expenses to find out why. :banghead:

But instead of putting a bulb in the circuit, or a resistor that would suck Amps for nothing, I came up with a simple electronic trick. (see schema)
The 2 diodes mimick a PNP transistor (which I would have used if I hadn't burnt them all in trial and errors).
The resistors ensure that when we apply 12V, the transistor blocks and all (most) current go through the LEDs. But if the tension drops to 7V (test tension of the ABS controller, max 50mA), the transistor becomes passing and the measure reads less than 1V making the ABS controller believe everything's OK.

At idle, that montage takes less than 1mA, and no more than 15mA when braking. Compare that to your X Amps through the resistor. :rolleyes:
Oh, and there is no more glowing either. ;)

T.

Awesome!
I will give this to my other RX-8 buddy at work (the electrical engineer at our company lucky for me) and have him put a couple of these "brake light foolers" using the PNP and see how it goes... thanks alot for doing the research! I always like the scientific approach vs. the bigger hammer approach. I guess that's why we have Wankels instead of Yenkos!

-C

p.s. I like the glowing at night!
Also, you only have to fool the circuit of the brakelight filament itself, not the running light circuit, but your drawings shows 3 filaments (bulbs)?

p.p.s. OH, I see you are referring to the third brakelight... I forgot, I have a rear camera in this location, and also the Pontiac GTO rear spoiler with LED light bar that apparently does not cause problems with the center bulb circuit.