I have an issue with my 04 MT rx8 with the ABS and DSC light illuminated. Heres what happen, I was driving back home (San Diego) from Bladwin park (4hour drive back and fourth). While on the freeway I set my speed to 75mph on cruise control, about an hour while on the way back to SD, I noticed my car started to decelerate and a cluster of indicators came on. I pulled over to the nearest gas station, let the car cool down abit and restarted the car. Everything seemed fine, no indicator lights what so ever. When i exited the gas station and i hit the brakes, I noticed my brakes made a weird noise, the best way to describe it was it sounded and felt like i was stepping on small rocks with metal shoes. Then the ABS/DSC light came on, I drove it the rest of the way home, brakes were still operational. When i got home, grabbed my Cobb to check to see any DTCs, and it wasn't able to find the code with the ABS/DSC indicators on. I searched the forums and read alot of possible fixes with this issue and i've tried a few of them with no avail. Heres what i've tried so far...

Removed neg battery cable over night to reset ECU...
Reseted and reflashed ECU with cobb countless times...
Removed all 4 wheels to check speed sensors all looked secure...
Checked clutch/brake sensor, looked fine no sticking or loose connections...
When i removed the right rear tires i noticed the lugnuts where loose, originally thought this might be the issue, corrected it but still get the abs /dsc light.
torqued wheels to 90 lbs, 35PSI on all tires..
Cleaned steering harness connectors and brake fluid sensor + dielectric grease...'

And no I don't have an LED 3 brake light... I only have LED parking lights in the front. 2 weeks prior to the long drive, I lowered my car about an inch and changed brake pads/rear brake lines + rotors/ bleed fluid with motul RBF 600... thought i just throw this in since it may be related... I haven't gotten an alignment either... When i restart my car, the lights go away but then as soon as I brake i get that weird noise and ABS DSC light up again... Anyone have any more ideas how i can fix this issue? I may throw in the towel and bring it to mazda next week... Please help!

 

I don't know if this could cause YOUR issue, but here's what happened with my TCS/DSC lights: Maybe check the Steering angle sensor?
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The CPU Re-Flash had been done about 8 months before, and this is about the time these errors started appearing. Sometimes when started, or while driving, the TCS/DSC lights would start going off. No rhyme or reason, but any of the following 3 scenarios could happen.

1 - All lights normal.
2 - TCS On, DSC Flashing
3 - TCS On, DSC Off

I had attributed these to the Re-Flash, and assumed it would be a simple software glitch that the dealer could get straightened out with yet another re-flash. Well, Stupid me... LOL! I took it in to the dealership yesterday to have that diagnosed, along with a rough-idle and poor fuel economy issue (I know there is no "good" fuel economy on an RX8, but should be better than the 11mpg on my custom Jeep Rubicon). It turns out it that the TCS/DSC is a very rare problem that the dealership's self-proclaimed "RX8 Specialist" had only heard about but never personally seen: a faulty Steering Angle Sensor. $310 just for the part. Repair is about 1.5 hours, so about $500 total.

Note: Also had Motor Mounts, Plugs, and Coils done...
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Turn wheel all way left then right and then go drive at various speeds. The grounding system and area on rx8 blows sometimes they loose grounding as the vehicle ages.

 

remove the LED parking lights and see if that fixed your problem.

 

ok found out the problem, took the car to school hook it up to the school uber scan tool. There was an issue with right rear abs/speed sensor "Missing input" C1235. pulled it out seems like my coilover KW external rebound valve was hitting the wheel sensor and shorted it. Called around local part shops, no one kept it in stock and was about $100.00 from dealer. bought some heat shrinks and repaired the original, works like a charm /