'02TA

I just put some M&H 325/45R17 DR's on my T/A. For about a week the ABS and BRAKE light have been coming on after about 5 mins of driving but nothing else happened the car drove normal. On my way to work today I put my car in neutral cause i haven't put in my stall yet and when i put it back in drive it SLAMMED into gear and then proceeded to not have any power to accelerate. When i got outta work today i started the car up, drove fine until the lights came on again and then BAM! same $h!t... I did do a search and found one thread about how the difference between the front and rear tire diameter may make a difference. i have just about a 3" difference so could that really be it????

'02TA

come on guys need your help on this one...

xbcrguy182x

Do you have TCS?

If all of this is began to happen after the new rear tires, then I would say that's throwing off the computer. Because the rear tires are moving at a different speed than the front tires. The computer doesn't know the difference.

'02TA

I don't have traction control. but I took the car over to the chevy dealership that my buddy works at and scanned the computer and some irregularities with the tps sensor voltage/signal came up so we swapped it out and now the car drives normally but the abs and brake light are still on. So i guess the tire swap made the lights come on but the lack of power and all around crappy drive ability was from the tps sensor...figures that the tps would go right after i did something to the car. just my luck.

tording99Z28

iTrader: (3)

If you do not have TCS then you should only have one sensor for the rear on the diff. If you changed the size of the front wheels though as far as diamter goes then it is still throwing off the ABS system and this is why you have the brake light and ABS light. There is no way to fix this other than removing the ABS system as far as I know.

'02TA

Is there any possible way that the tires size difference tripping the abs inop light and brake light could cause the car to go into limp mode????? I thought I figured out the no acceleration and hard shifting issue by replacing the tps but it's still doing the same thing with a brand new tps. The thing that's throwing me off is that its intermittent and i can sometimes solve it by turning the car off and back on but sometimes that doesn't work either.

'02TA

Scanned it again today and the map sensor code came up twice. Could that cause the car to go into limp mode???

TireSm0ke

iTrader: (1)

Your TPS may not have been the problem. When the PCM senses a serious malfunction in one or more of your sensors, it does things like pull timing, adjust your shift pressure to 100%, among others. Did you do alot of hammering to fit those tires in there? You could have knocked a wheel bearing and caused your rear wheel speed sensor to malfunction. The tire size on the rear shouldnt be an issue, ive seen people go bigger on the rears without problems. If you were to run a spare on one side up front with a full size tire on the other side, you would have the same problem.

What size tire are you running up front? Clear the code for the MAP sensor and see if it comes back, if it does let me know.

'02TA

I cleared it and the map sensor code came back twice...Im running a 255/45R17 up front

TireSm0ke

iTrader: (1)

It could be because your running a 255 up front. Id go with nothing smaller than 275 when running 315 or bigger out back.

'02TA

Would that cause it to go into limp mode?

'02TA

bump...

hadkin

iTrader: (3)

I've had a similar problem and i'll share you my story. I have different size tires up front then in the back, was never a problem till i swapped my rear end for a moser 12bolt. Now my abs constantly goes off. They say its cause of the different tire sizes, but i never had that problem before...
Anyways, for now I pulled the plug in the wirebox for the ABS/brakes and the car drives fine.
I might change my sensors like you did soon. For you, i would highly suggest getting a stall back in there ASAP. most of your car issues will go away, except for maybe the light...

Ps. my front is a 275/40/17 9.5 inch rim and the same for the back, but on a 10.5 inch wide rim. driven 25k miles on it no problem.

'02TA

What plug for the ABS did u pull??? The one in the diff or a different one?

Scarlet_Spider

I have the same problem. my Abs inop light comes on, Brake light. I also have TCS and that comes on at the same time after about 20 mins of driving. My car has felt like a 4 cylinder since the problems first started, and i made 112 miles on 1 tank full which is horrible even for a V8. At this point im going to look for an LS1 speed shop to determine the problem and take care of it correctly. Tire size has nothing to do with it. I believe the mechanic who worked on my car damaged my sensors. o yea now my car has to Ignition coils misfiring.... fun times. for more of my nightmare click here https://ls1tech.com/forums/general-m...-trans-am.html

Scarlet_Spider

Best of luck with your issue if i find any info on mine i'll be sure to share it.

'02TA

I still haven't figured out the problem yet but i checked my oil because it was about time for an oil change and it was a little low...nothing ridiculous, about a quarter quart. ever since i added that little bit of oil, it hasn't gone into limp mode as much... and when it does a few floggs to the gas pedal and she runs good again. this problem really has me stumped???

hadkin

iTrader: (3)

sorry for bringing old posts from the dead. I pulled the circuit plug from under hood.

more interesting, I think the abs,break light, and traction control thing went off because my mechanic was a moron.

I think three possibilities existed:
1. he didnt put on the rear end exacltly inline

2. he killed a sensor

3. he put on the ABS wheel thing backwards. I've seen a thread where this has happened. its easy. both directions fit, but one direction slides a slight bit closer to the rotor (when put on backwards).

hope this helps anybody who currently is having this issue.