2002 Chevy Cavalier- Trac Off and Check Engine light are on and the car is shifting hard.


Asked by Apr 15, 2015 at 07:20 PM about the 2002 Chevrolet Cavalier

Question type: Maintenance & Repair

I have a 2002 Chevy Cavalier that just hit 102 thousand miles and all of a sudden the
engine started running at very high RPM's and the transmission is shifting really hard,
the speedometer is not working, the Trac Off and Check Engine lights are both on, and
the car makes a clunking sound shifting into gear.

I see this seems to be a common problem with Cavaliers so I am wondering what you
think could be causing this. The Trac Off and Check Engine light are both on so I
brought it in and had it scanned. The trac off light is showing "Vehicle Speed Sensor-
low input" and check engine is showing a "bad O2 sensor".  I brought my vehicle into a
local repair shop and paid $120 to have the vehicle speed sensor replaced and they did
some other voltage testing but it did not fix the problem.  They said it was my
transmission and wanted to drop it and change the fluid and filter for $250.  I dont want
to spend that kind of money just to see if the tranny is bad when I have not had any
signs of it slipping or starting to go out.  

I did some research online and found that it could be a number of different problems
besides than the transmission that could be causing this.  The TPS  seems to be a
common problem that I keep reading about and also the wheel speed sensors.  I also
read that faulty spark plugs could be the cause of the problem.  Not sure what steps I
should take or what I should do first without spending a bunch more money and not
fixing what is causing it.  Any help or input would be greatly appreciated!

10 Answers


Have a scan done


If your speedometer and tach are not working, the car won't shift correctly. The computer needs these inputs in order to know when to shift. Get a new gauge cluster from the salvage yard. I know this is the case for Toyotas. Not a Chevy guy so I'm not 100% sure.

1 out of 1 people think this is helpful.

Scan done. Check Engine Code P0502- Vehicle Speed Sensor Circut Low Input. Vechicle speed sensor has already been replaced and it did not fix anything.


Here's my take on it. I'm not an electrical engineer nor do I know how your cars computer system works. Since it's saying low input, does that mean it's not getting enough info due to the fact that your speedo is not functioning? As I said before, this holds true for Toyotas. I would suspect that it would hold true for your vehicle as well. Before I spent a ton of money bringing it to a dealer, I would hit the salvage yard and swap out speedometers. You need one anyway. As far as your TRAC light, when you have the CEL illuminate, that automatically will trigger the TRAC light also. It doesn't mean that there is anything wrong with the TRAC system. I'm not sure how your whole system works, but on some systems the ABS works in conjunction with the VSS. I would check your wheel sensors and see if you have any broken wires. Here's a video: https://www.youtube.com/watch? v=nBqZ6lQ3IVQ I would also change shops. What was doing a tranny flush for $250 going to accomplish with a CEL and a speed sensor code? Nothing, besides screwing you out of $250. Check out the video and see what you think.......

3 out of 3 people think this is helpful.

more info: http://www.engine-light-help.com/speed-sensor.html

2 out of 2 people think this is helpful.

Check Engine Code P0502- Vehicle Speed Sensor Circut Low Input. VSS (Vechicle speed sensor) has already been replaced, MAP sensor has been replaced, Gauge cluster has been replaced and I have not had any luck. Should I try be replacing the TPS (throtle position sensor) or could something else be causing this??

2 out of 2 people think this is helpful.

So what is the car doing as of right now? Still revving high and the tranny is still clunking? I believe the reason that your tranny is clunking is due to putting into drive with very high RPM's. You may have a bad tranny mount which is causing the clunk noise. Remember there will be much more torque when slamming it into gear with a high RPM. Have you tried replacing your Idle Air Control valve?

2 out of 2 people think this is helpful.

My car starts up and idles normally, everything fine when I put it into reverse to back out of the driveway. Sometimes there is a loud clunk when I shift into drive but not always. The RPM's are not always running high, only when I shift into gear and take off from a dead stop. When I shift into drive from of park or reverse and begin to take off down the road, the tranny seems like it is not wanting to shift out of first gear, the tach shows very high RPM's (around 4200-4500) and then the car shifts very hard and jerks into the next gear. It seems to only get stuck at running at high RPM's when first taking off from a stop and driving in first gear, once it hard shifts out of first gear the rest of the gears seem to shift ok but are still jerking a little harder than normal. I don't know what else I can do to try and diagnose the cause of the problem


Have you pulled your transmission fluid stick and checked it? You must check transmission fluid with the engine running. Just in case you didn't know. Try cleaning you Mass Air Flow sensor. I have read other posts and they said that after changing out the TPS and cleaning the MAF, they noticed a difference. Also remove your throttle body and clean all of the carbon from the butterfly. Too much carbon may be causing it to not close all the way.


I have an 02 Cavalier. Starts fine, stays running but shifts hard, late shifts and rpms fluctuates. I disconnected the battery to reset the comp. The trac off light and engine light hasn't came back on yet. Ot just shifts jard and have to be at high speed or the rpms have to rise over 3k.

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