SES and TCS OFF lights on
Thread Starter
Teching In
Joined: Jan 2003
Posts: 22
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From: Midland,Texas
SES and TCS OFF lights on I was driving down the highway and the transmision starts cutting out. The TCS OFF light comes on and I can't turn it off by pushing the TCS button. Then the SES light comes on. When the transmission shifts through the gears it "double shifts". It hits two times in each gear like it didn't engage the first time. Then in overdrive at 70 mph it studdors like it's trying to shift again. Why is the traction control light coming on? Why can't I turn it off? This is NOT the "low traction light". It doesn't come on.
On The Tree
Joined: Feb 2004
Posts: 193
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From: Central, Fl
Originally Posted by JWest
I was driving down the highway and the transmision starts cutting out. The TCS OFF light comes on and I can't turn it off by pushing the TCS button. Then the SES light comes on. When the transmission shifts through the gears it "double shifts". It hits two times in each gear like it didn't engage the first time. Then in overdrive at 70 mph it studdors like it's trying to shift again. Why is the traction control light coming on? Why can't I turn it off? This is NOT the "low traction light". It doesn't come on.
Does the crappy performance only occur when the TCS light comes on? Or does the crappy performance occur then the TCS light comes on? Take the fuse out for the TCS and see if you can get away from the crappiness. Could be in the TCS system.
Scan the codes, it will probably be MAP/MAF related or P0121 Throttle Position sensor performance. The TCS turns itself off when the readings are in conflict and the PCM goes in to speed density mode, which is probably the loss of power you're feeling.
It's all in the tuning. When the speed density calculation differs from the MAF reading enough the PCM has a shitfit.
If your car is stock it's probably a failed TPS/MAF/MAP sensor - the code should tell you which one.
I'm trying to learn more about this behavior myself - if anyone has any info please enlighten us !
Bad30th
It's all in the tuning. When the speed density calculation differs from the MAF reading enough the PCM has a shitfit.
If your car is stock it's probably a failed TPS/MAF/MAP sensor - the code should tell you which one.
I'm trying to learn more about this behavior myself - if anyone has any info please enlighten us !
Bad30th
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Betcha it's P0121 Throttle position sensor performance. That's what it always is on mine. It can also be a P0101 MAF code if the PCM thinks its the MAF and not the TPS that's off.
The A/C on will affect the MAP and MAF airflow enough to throw the speed density calculation out of whack if it's on the verge of the variance already. The PCM is consistently checking the MAF value against the speed density calculation to make sure they jive with eachother. When they don't the TCS turns off, and the PCM resorts to speed density.
For a given amount of airflow, the PCM expects a certain MAP and MAF reading. Drilling the TB hole too big can whack this airflow calculation, some big cams can whack this calculation due to changes in MAP for a given airflow.
Please someone correct me if what I'm saying is wrong, but this is what I've seen based on personal experience.
Cheers,
Rob (Bad30th)
The A/C on will affect the MAP and MAF airflow enough to throw the speed density calculation out of whack if it's on the verge of the variance already. The PCM is consistently checking the MAF value against the speed density calculation to make sure they jive with eachother. When they don't the TCS turns off, and the PCM resorts to speed density.
For a given amount of airflow, the PCM expects a certain MAP and MAF reading. Drilling the TB hole too big can whack this airflow calculation, some big cams can whack this calculation due to changes in MAP for a given airflow.
Please someone correct me if what I'm saying is wrong, but this is what I've seen based on personal experience.
Cheers,
Rob (Bad30th)
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Verdad Gallardo On The Tree
Joined: Feb 2004
Posts: 193
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From: Central, Fl
Originally Posted by Bad30th
Scan the codes, it will probably be MAP/MAF related or P0121 Throttle Position sensor performance. The TCS turns itself off when the readings are in conflict and the PCM goes in to speed density mode, which is probably the loss of power you're feeling.
It's all in the tuning. When the speed density calculation differs from the MAF reading enough the PCM has a shitfit.
If your car is stock it's probably a failed TPS/MAF/MAP sensor - the code should tell you which one.
I'm trying to learn more about this behavior myself - if anyone has any info please enlighten us !
Bad30th
It's all in the tuning. When the speed density calculation differs from the MAF reading enough the PCM has a shitfit.
If your car is stock it's probably a failed TPS/MAF/MAP sensor - the code should tell you which one.
I'm trying to learn more about this behavior myself - if anyone has any info please enlighten us !
Bad30th
So do you think this is tuning issue, or do you think I could just replace my tps and fix this. Has anyone found a solution to this??
I went to the track last night and for the first time and was pretty disappointed. Although the light was not on when I was racing because I didn't turn the a/c on, I was only trapping like 107 mph with all the stuff on my sig I should be like 4-5 mph faster.
See what code it is, you need that before we can even begin to help. Any semi serious driveability issues (enough to affect the way it runs) will switch the TCS off automatically. If it only does it with the A/C on, the extra load on the engine may bring out or enhance the bad behavior. You may even have a compressor locking up. We need more information to be able to help you.
On The Tree
Joined: Feb 2004
Posts: 193
Likes: 0
From: Central, Fl
Reading that thread, I think maybe the A/C high pressure switch, could be it, I will try disconnecting it. Since this does seem to happen when I turn the a/c on it makes sense. I don't think it would be the shaner throttle body since I installed it over a year ago and never got any codes from it until now
On The Tree
Joined: Feb 2004
Posts: 193
Likes: 0
From: Central, Fl
I hate to dig up an old thread, but I finally got around to replacing the high pressure a/c switch, and I am still getting the problem. Any other ideas on this guys? I would like to avoid having this tuned out if possible. Has anyone solved this without tuning? It seems to be mostly people with aftermarket cams having this problem.
You can resolve the code with tuning, but it doesn't resolve the root cause, it just makes it not throw the code.
To desensitise the code, change the P0121 MAP window settings on the code to Min 35 Max 100.
To correct the root cause, figure out why your MAP vs. TPS vs. MAF values are out of whack vs. your tune.
For most folks, just desensitizing the MAP window is good enough.
Bad30th
To desensitise the code, change the P0121 MAP window settings on the code to Min 35 Max 100.
To correct the root cause, figure out why your MAP vs. TPS vs. MAF values are out of whack vs. your tune.
For most folks, just desensitizing the MAP window is good enough.
Bad30th
