TCS or Tires?

[Doghauler]

Hello, Newbie here....I've been searching on this subject for about a week and now I need help. I'll try to be as complete as possible.

I own a 94 w/manual trans and I am experiencing continual activation of the TCS system. Pretty much everytime I accelerate it kicks in and the green light blinks. Road conditions do not matter (wet, dry, bumpy, corners, etc) it always activates. My tires are as follows:

rear - 245/40-17 (stock size for a 94)
rear wheel size - 9-1/2 x 17 (stock is 9"?)
front 205/50-16 (not stock)
front wheel size - 7-1/2 x 16 (stock size)

I have the shop service manual and I have run all the diagnostics, for a code I get one blink of the TCS (yellow center light) and then it stay on. (Insert jumper, turn on key, TCS light off once, then on, stays on) This suggests replacing the TCS computer.

I have reset the computer by pulling the fuses, but even after doing so I get the same result when I re-insert the jumper. (no driving in between)

Here are my questions:
1) can the 9.5" rim on the rear essentially reduce the rear tire size enough to cause an issue? I have read a lot of you are running the same TIRE size I am on the F/R and are not having TCS issues, but I'm not sure about the rims.
2) Why would I not be able to clear the "Off once-on-always on" code from my TCS computer? As I understand (albeit limited!) pulling the clock fuse and/or the ABS 2-3 fuse should erase the code.
3) If it is in fact my TCS computer, from reading here I understand I can simply pull the 3 molex plugs and be good to go until I get it replaced.
4) Anybody have a TCS computer for sale cheap?

Thanks a lot everyone. I hope this is complete enough.

Jeff

 

[Briank]

You have read this http://www.nsxprime.com/FAQ/Troubleshooting/tcs.htm

check the main relay.

 

[Doghauler]

Thanks for the info Brian, I had not come across that yet. I assume by "main relay" he is referring to the one behind the passenger seat, labeled (oddly enough) "main relay"....go figure. I removed it and resoldered all the connectors on the circuit board, but the problem still exists. I find it strange that I cannot clear the TCS trouble code I am getting, TCS light on, blinks off, then on and stays on. The funny thing is that the problem is intermittent, sometimes the TCS works exactly as it is supposed to, other times it activates fully and continually blinks (green light). To me, that points to a mechanical issue (connection or wire). Also, the fact that the TCS works properly sometimes would indicate my tires sizes are ok, otherwise I would expect it to activate every time.

Any other hints would be helpful, thanks everyone.

 

[Jin1976]

Your front tires are too tall. Try using 205/45/R16 maybe that is the cause of the green TCS light blinking. For the TCS code it could be the wire harness failure or the TCS unit itself is bad. Check page 771 of 1420 of the repair manual.

 

[D'Ecosse]

Your front tires are too tall.....

I agree - 50 series definitely the issue here. Worse if your rears are worn (which they typically are) relative to your fronts.

 

[Joe Gliksman]

I had the same, especially as the rear tires wore faster than the fronts. I just ordered one size larger rear tires.

 

[Doghauler]

Tires huh? That was my first thought, but after searching here I thought I had fairly well eliminated that as a possibility. I know some of you run the 50's on the front without problems, but possibly my setup is close enough to the edge of the tolerance to cause a problem. Now if I could only find a couple of 45's to slap on as a test! I've pretty much eliminated all other possibilities after all the testing and troubleshooting I've done over the past couple of days, so it looks like the TCS computer or the tires are the only viable possibilities.

Thanks for all the responses, and if anyone else has an idea I've overlooked, let me know.

Thanks again!

 

[nsxtasy]

Theoretically, it shouldn't be the front tire size. 205/50-16 is 1.9 percent larger in diameter than the stock 215/45-16. When used with the stock rear size, that should not be enough to activate the TCS. Other factors may also play a role - front-to-rear differences in tread depth, differences between labeled size and actual size, etc - but 1.9 percent isn't all that much and I would look elsewhere for a possible cause.

My recommendation - get together with another local NSXer and swap your front wheels/tires with his, then take your car for a ride and see if the TCS still activates. That should tell you whether or not the tire sizes are the cause. (Don't do this with the significantly smaller 15" size of the '91-93 NSX; try it with either 215/45-16 or 215/40-17 fronts, which are within 0.7 percent of each other in diameter.)

 

[jimbonuttz]

curious...did you ever figure out what was wrong and what was your solution to this issue?

 

[Doghauler]

Actually, not yet. I am just now getting my car all ready for the year. (pretty much sits for the winter in my area) I have new tires on the way, they are being delivered this Thursday (stock size) so I'm hoping that cures it.

 

[Doghauler]

Solved -Tires.

I replaced all 4

old sizes:
rear - 245/40-17
front 205/50-16

New:
rear - 245/40-17
front 205/45-16

TCS now works like it is supposed to, car rides smoother, and it also eliminated a front end "resonance" type vibration. Money well spent!

(Eagle F1 GS-D3)

Thanks!