tricking the pcm
 

so i have my abs light, brake light and tcs light on, the dealer says its because of the tire size i have in the front which is 215/35/18, is there a way i can get the computer to see these tires as ok so it stops triggering these lights to come on? the dealer wouldnt help due to liability issues

get in there and remove the bulbs

lol, the tcs and abs will still work right? or no? is that the only way to do it? i was thinking the dealer could just reflash it or something to say hey those tires are ok you know? but they wont help at all

those lights are on due to tire size? that doesn't make any sense

yeah i know but thats what they said, i thought it might be because the recall power issue update but they did that and it still came on, i guess the pcm is programed to those tires and when the speed sensors sense the tires at a diff speed or soemthing since they are diff size and are not going at what they should be going at compared to the stock tire size the speed sensors let the pcm know so then the pcm illuminates those lights, i dont know why they wont just reprgram the pcm to my new tire size

are the front tires the same diameter as the rear?

im not sure, rear is 255/40/18 front is 215/35/18

your problem is that your rear tires are taller(bigger diameter) than your front...

oh snap

if i went to 235/40/18 in front do you think that would work or no? i dont want 40 in back and 45 in front, is there a way i can leave tires how they are for now and get lights to go away or no?

i like taller in back, i like the raked look

215/45 would prob be better but you could start with the 215/40 and see if it works

do you mean you like wider in back? cuz taller in back would look like poopy

well fist im going to see if there is a way around getting diff tires, if not then i will try 40 first, no not wider, i like it taller, not like way tall, 40 in back and 35 in front is minimal enough to make a slight difference but still looks good as apposed to same height all around

If you want the raked look, lower the car.

The only way to get rid of the lights is to get the same diameter tires all around. Without the same diameter tires, the TCS/DSC and ABS will not work properly and will kick in at random times during normal driving.

Just for some info:

Stock 225/45/18 = 26 inch diameter

255/40/18 = 26 inch diameter
215/35/18 = 23.9 inch diameter
235/35/18 = 24.5 inch diameter
225/40/18 = 25.1 inch diameter
235/40/18 = 25.4 inch diameter
245/40/18 = 25.7 inch diameter

If you wan to calculate anymore here is the link:
http://www.miata.net/garage/tirecalc.html

You have a 2.1 inch difference in diameter from front to rear, that is why the lights are on and they will continue to stay on unless you get the tires closer to the same height. Like I said before, if you want a raked look, lower the car. Tein S-Techs will give you the look you are going for with the front being just slightly lower than the rear. If you want more drop in the front than the S-Techs, you will have to go coilovers.

Also, as far as I know, there isn't any way around these systems and there is no way of tricking them.

Tire height needs to be the same.

suck, do you think if i went with the 25.4 inch diameter (235/40/18) it would still trigger the lights or do you think it will be close enough to not trigger them? i already have the s-tech springs in the front, stock in back

also juice thanks for that chart helped alot

tire dia. has to be the same front to rear.

it is that simple.

beers :beer:

that sucks

does driving like this damage anything?

it has to be the same size (front and rear)

if not, the computer will sense different speed between front and rear and "thinking" that your car might be slipping or some sort of sensor malfunction.

and when the lights are on, ABC/DSC will be DISABLED. Dont say I didnt warn u.

It won't hurt the car other than its performance. It could also be dangerous to drive the car in this condition since all the systems will not function properly. Once the problem is rectified, and assuming you didn't crash your car, the car should return to functioning normally as if there was never a problem.