Hi I am a new bees here, and I meet this weird problem here and I ve done some search but none of them fixed my issue here.

I have a 05 RX8 Automatic. And it now have both ABS light, Power Steering light, Parking light, and a bad speedo on at the same time as well as the Check engine light on with a code of U0121. And this is kinda weird and ill try to explain my problem as clear as possible and hope somebody pro can help me with my problem.

Basically, everything started as I left my car with the headlight on and drained the battery. Then I jump started my car and drove for about 1 hours that night and everything seems fine that night. The other day I realized that after I driving for a while the check engine light came on and then came the ABS, POWER STEERING, PARKING BRAKE LIGHT as well as the SPEEDOMETER went not functioning. It is like they keep working for like a minute and stop working another and goes on and on like that.

Btw, the Traction Control Light is not on could it because that there is no TC system in the automatic lololololol?

So the first thing I thought is that I have to check the code so I went to AutoZone and got a code started with a U... lol.... it is U0121 and it says its the computer cannot communicate with the ABS or something like that. And after searching online I thought it could be a dirty wiring or some plug got unpluged kinda problem. So I went underhood with wire cleaner and di-electric grease for 2 times and the problem is still there after I cleaned the code.

And I found out that the coolant level sensor was unpluged so I found another problem Oh Yeah that was a happy lol!

And that was about 3 days ago.... I suddenly realized today that it could be a unstable battery so I went to the AutoZone again and got it checked. They said it was indeed a bad battery and gave me a new one. And after I wait till the code got reset, and put it on and drove it for about 30 second... the problem came again.........

This is what my car normally look like right now(in Attachement)

What problem could it possibly be? Speed sensor? ABS sensor? I just dont have the money to got it fixed in the dealership plus I hate those douchebags because once they wanted to charge me for brake pads and rotors for $2500 they are just ridiculous racist ********... I am not stupid enough to pay those guys what they want.

I need HELP T.T...... Please.... Somebody

P.S. Please forgive me about this horrible English grammar...I am from China and I am just bad at English lolol

 

I ve changed the battery, the battery terminals, took the air box out and cleaned and applied di electronic grease to every plug ive seen... and the problem is still there....anyway... im waiting till the car cool down and get the coolant change...

 

So about that dielectric grease... it's OK to put it directly on high pressure contacts, like a spark plug wire, but it's not recommended on the contact surfaces of light-duty connectors, like sensor plugs. The grease is an insulator, if there's not enough pressure for the metal contacts to cut through the grease, there won't be any contact.

So if you really put it inside every plug, go clean them off

 

I did not put it inside every plug... i just followed the process of this DIY post here :

https://www.rx8club.com/series-i-do-...g-pics-223713/

 

ok, so i am certainly no expert, all information i know i have learned from the "real experts" here on the forum.....
I will quickly list a few things to clear them up for you...

The u code (U0121) you got when scanning your car was a communication error between the OBD scanner and the port itself (may not have been plugged all the way in).....usually disconnecting and reconnecting the scanner will fix this, or the OBD scanner isnt compatible...you may want to try to have that CEL scanned again to see what the CEL really is....

I own an A/T RX8 and there is traction control & dynamic stability control but is based on the specific model RX-8 you have...Grand sport, Grand touring etc...some have it, some dont...

The Power Steering harness can be cleaned, but also, you will want to reset the steering angle sensor......(procedure is below)
1. Turn the key to acc (do not turn the engine on)
2. Turn the steering wheel all the way to the left, then all the way to the right and then back to centre...You should see the DSC or TC light flash a few times on the dash
3. Turn key to off and then start the vehicle

Your coolant bottle was most likely unplugged because of a faulty float inside of the coolant bottle (well known fault with the RX-8)....The sensor usually gets unplugged because the float is malfunctioning which in turn throws a symbol on your dash (the one you have which resembles a red castle) which is to signify you are low on coolant.....most people who have a faulty sensor just unplug it so they dont have to look at the symbol on the dash BUT..you have to manually monitor your coolant levels and this is only recommended if you know your coolant system is working 100% fine...

I recently did a coolant flush a few weeks ago and it has actually turned off the coolant light that was appearing intermittently for me..


As for the ABS light and speedometer malfunctioning,would it have something to do with your battery or alternator.... maybe a short in the wiring? i have no clue.....maybe someone with more expertise (ONE OF THE REAL EXPERTS) can chime in and help you out....

Hope this may help and hope you get her all fixed!

Regards,

Big Fella

 

Thank you guys I'll definitely check those things you mentioned again and see if it will work......or I'll wait my money from China and go to a shop

 

I would disconnect the negative terminal of the battery, then make sure all of the connections in the engine bay are secure, including the connections to the ECU (unplug and clean with electrical cleaner), EPS brain, and EPS noise filter in the ECU box and all grounds. Then reconnect the battery and if it doesn't fix the issue then you need to check the charging system to ensure the alternator is working correctly. Autozone, etc can run a charging system test while the car is running if you can't do it.

 

did u ever get this problem fixed because my rx8 is doing the exact same thing

 

Sorry, I ve left US and went back to China for about 2 years. Wasn't able to get the car fix.... my best guess is a bad power wire to the ECU or a bad ECU...in my case, I might need a new alternator as well since I had left the headlight open and put the old alternator under extreme load when I used it to charge the battery full... But the car endup getting stolen right after I left. And I wasn't able to come back to US to get the car when the police found it so it end up in an auction.LOLOL...

Just check the used market and find all those part... you can get them as low as $100-200 since there are so many broken RX8 out there... But to be honest, if you have a AT version like I had, and end up finding the fix would cost more than $300, just sell that junk and buy a new car... With all the respect to those engineers in Mazda... RX8 is just... a giant middle finger to the world...

 

OHHHHHH and I totally forgot this..... There is a thread talking about some kind of a wire connector underneath the transmission/ near the exhaust pipe....They said that dirty/bad connector would cause all these problem as well.... Just check online and search on different forum... and make sure you get that fix first before all those ECU and Alternator crap. It worth a try...

and try to read this thread and see if it helps
https://www.rx8club.com/series-i-tec...lights-129489/

 

 

i had the same problem. You Just need to buy a ABS Unit used or New for the same spec of your car. Example: AT-6 gears you need to buy a AT-6 gears.
If you buy a wrong one, you will need to go to Mazda to configure It.
Its easy. Just plug and play!
i did and now works normally.












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You need to change the ABS unit. You need to buy a New orA used one for your car spec. Its easy to remove. Plug and play. I did and my car fixed. I got the exactly same problem.