"tcs off" light comes on

[pimpin83]

I just got a 95 millenia s. When I drive it for a little while, the "tcs off" light comes on randomly and stays on until I turn the car off. When it comes on, also, the car starts jerking and it won't go past 70 mph. Also when I try to go up a hill, the speed starts dropping with the "tcs off" light on. Why is this? If someone could please help, I would really appreciate it. Thanx.

[Screlz]

Hi, I know what you are talking about but with me its a bit different. I have a 95 Mazda Millenia and usually I have the TCS (Traction Control System) off. But Yesterday I was on the highway. I floored it for a bit then the light came on. I think it burns something out if you keep it on. I just try to keep it off and only use it when it rains. My car doesnt jerk though, it just emits a burnish type smell from under the hood. No smoke is visible though.

[pimpin83]

hey, i don't know if that's the same problem as mine, but i'll try it, and thanx again!

[IcedTahoe]

Hey Pimpin83,
Have you got your problem with your Millenia resolved. I have the exact same problem. Mine has been in the shop just about all of 2003 and noone can figure out what the problem is. First they said that it was the computer, replaced that, didn't fix it. Then they said it may be the ABS/TCS computer but weren't sure because they didn't have schematics from Mazda. PLEASE let me know if you found the resolution to the problem.

[pimpin83]

I still haven't figured it out yet either. It might be the O2 sensor. I just don't know yet. So many things popped up on my car. Now its in the shop for broken camshaft! If I find out, I'll definately put it up on here first thing!

[msellers]

I have the same problem as everyone else on the board with the tcs light and the jerking of the car. The first thing I did was to change the o2 sensor on the exhaust pipe(one of 3 on the car) with no change. The next thing I did was to change my fuel from 91 to 89 octane. This dropped the frequency of the problem dramatically but did not completely eliminate the problem. Now I'm looking into the vacuum system. This appears to be the problem since the tcs light never comes on while I'm driving on the highway but occurs when I'm doing stop and go driving. It makes me think I have a leak in the passive vacuum system. Small enough to not effect day to day operations but enough to give the ecu unit headaches and to activate the tcs off light and whatever goes on under the hood after that. As with all of you, by turning the ignition on and off you reset the tcs off light. The second time it occurs the check engine light goes on as well. After that the system will reset completely after 10 of so starts and the process begins again. Anyone nail this problem yet? It appears to be endemic of the Millenia S. Any help would be appreciated. By the way, my sister owned this car for 7 years and never had this problem. It started after I bought it from her and started using 91 octane instead of the 89 she always used.

[msellers]

I had the same problem as everyone else. The tcs light would come on and the car would stutter on acceleration. If I pulled over and restarted the engine the tcs light would go out and the car would function fine until it happened again and then I would pull over and start the engine again and the tcs light would go off but the check engine light would then be on until I started and stopped the car many times and then the cycle would begin again. The Millenia S 1995 and up have a OBD II diagnostic port. It's under the dash on the driver side on the right side of the steering wheel. I put my code reader on it and it said Air bypass valve. I checked the hoses and sure enough one of the smaller hoses was cracked and wouldn't hold vacuum. This made sense because the tcs light never came on when I was going steady on the freeway(plenty of vacuum) but would always occur at low speed or stop and go traffic(low vacuum hence a small leak would impact performance). Hope this helps. By the way the location of the air bypass valve is shown under the hood of the car where you are shown the vacuum schematic.

[vladtapia]

your mass air flow sensor is damaged. You need to purchase a new one. It cost $200 - 300 online. You can install it yourself. Takes 5 minutes. Don't go to a mechanic, they will rob you saying it took hours to fix, very simple problem. The mass air flow sensor is connected to the coolent, in front of the engine. Look for it. I had the exact problem, took 3 weeks for the mechanic to figured it out. If you keep driving with the damaged mass air flow sensor, it will damage your oxygen sensor and a few other sensors thus costing you alot of money those fix those. Hope i was of help.

[msellers]

Thanks for the info, however, my problem was a vacuum leak at the air bypass valve. I have had 3 others contact me directly with exactly the same problem and each were found to be vacuum leaks and the problem was corrected. Also, I have recently put on the OBD II reader just to see if I had any more problems I wasn't aware of and there were no codes stored.

Thanks

Mike

[thojawan2000]

Originally Posted by msellers

Thanks for the info, however, my problem was a vacuum leak at the air bypass valve. I have had 3 others contact me directly with exactly the same problem and each were found to be vacuum leaks and the problem was corrected. Also, I have recently put on the OBD II reader just to see if I had any more problems I wasn't aware of and there were no codes stored.

Thanks

Mike

I just brought a 2000 Millenia S and I am now experiencing the sme problem. I went to AutoZone and got the Air Bypass Valve codes. The dealer said this part costs 649.00 then labor. How much did it cost to fix your car. I'm just looking for the upside in this car.

[MillyVanilly]

Originally Posted by msellers

Thanks for the info, however, my problem was a vacuum leak at the air bypass valve. I have had 3 others contact me directly with exactly the same problem and each were found to be vacuum leaks and the problem was corrected. Also, I have recently put on the OBD II reader just to see if I had any more problems I wasn't aware of and there were no codes stored.

Thanks

Mike

i recently custom-made a short ram air intake for my millenia. looks nice and sounds nice..not sure about performance boost though. anyways, after i finished installing, the TCS-off light and the TCS-on light were both on. how can this be? i did not feel any decrease in performance because of these lights being on though. any ideas on what i did to cause this? ..maybe vacuum leak ??
thanks in advance for any inputs.
-peter

[MillyVanilly]

oh, another thing in regards to what i wrote above:
the TCS-off light is ALWAYS on(along with check engine light =/ ), but the TCS-on light comes on after i drive around for a little while.
my dash cluster looks embarrasing with orange check lights on all over =/////

[maddin]

hello,
i have the same problem. How I can locate the Air bypass valve?

[msellers]

The Air Bypass valve location is shown on the vacuum schematic decal on the bottom front of the hood. Take off the 4 bolts holding the plastic engine cover and pop off the cover. You'll then see your vacuum hoses leading to the valve. There are 2 or 3 - 1/4 inch hoses leading to the base of the valve and one or two 3/4 inch hoses attached to the valve itself. One of these is either split or has fallen off, most likely the smaller ones. Pull them and inspect and splice in a repair. This should cost you $.50 and take around 10 minutes to repair. Remember you have a vacuum leak nothing else.

[rdorn]

New post, old thread... none the less it was critical in fixing my 99 Mazda 626 V6 . Same issue- intermittent problem: a sudden lag and TCS, TCS OFF, ABS, check engine lights when lagging occurs. This has happened twice. Both times it was the vacuum hoses which attach to the Solenoid valves, one hose attached to a Solenoid valve and intake (pink arrow), the other hose attached to the other Solenoid valve and Idle Air Control valve (pink circle). I had this issue twice because when the engine was replaced before I bought the car, apparently the posts at the Solenoid valves where the vacuum hoses attach were snapped and the hoses were both attached with epoxy.