2002 Camry cruise control and speedo problem

[02 Ateva]

I noticed a couple of times now that the speedo in our 2002 Camry 2.4 auto doesn't always move smoothly while accelerating or slowing down. It kinda gets stuck along the way for a split second and then jumps to the current speed.

Also sometimes, when driving slightly uphill on cruise control the car doesn't hold the set speed. It accelerates just above the set speed, then drops just below only to accelerate again. Very annoying.

It seems to me that these two conditions could be related. Maybe a faulty speed sensor?

What makes it difficult is that both are sporadic issues. I've driven up the same roads on cruise with the car being just fine.

Has anyone else experienced this? Any ideas how to diagnose this?

[aem]

Also sometimes, when driving slightly uphill on cruise control the car doesn't hold the set speed. It accelerates just above the set speed, then drops just below only to accelerate again. Very annoying.

That's normal, when going uphill/downhill the engine has to increase/decrease speed due to more work/less work done.

[02 Ateva]

Also sometimes, when driving slightly uphill on cruise control the car doesn't hold the set speed. It accelerates just above the set speed, then drops just below only to accelerate again. Very annoying.

That's normal, when going uphill/downhill the engine has to increase/decrease speed due to more work/less work done.

I know what you mean but what our car does is more than just that. I just took the car for a drive to take a closer look at what it actually does and now i'm very sure both issues are related.

Driving at a constant speed of lets say 60 km/h and looking at the speedo, the needle occasionally jumps to 58 and after 1-2 seconds jumps back to 60. This "jump" is not normal. When I release the accelerator at 60 a tiny bit and the car acually does slow down a bit, the needle moves smoothly (normal). Also the engine speed remains the exactly same when the speedo does these jumps.

When this happens with cruise control being active the car will instantly accelerate when the needle dropped. This is odd since the car didn't actually slow down. Now the needle jumps back to the actual speed of now just above 60 (since the cruise control accelerated) and the cruise control releases the throttle to slow down to 60 again...and so on.

[aem]

So during cruise control the car speed changes backware and forward? Are you sure you are not on a slope?

[02 Ateva]

So during cruise control the car speed changes backware and forward? Are you sure you are not on a slope?

yes, it does and it does it on a level road too. But it gets more noticable on an incline as the engine needs to work harder to accelerate the car.

The speed doesn't change dramatically, only about 3 km/h maybe (just enough to compensate the sudden "jumps" of the speedo). Meaning from the perspective of the cruise control this response makes sense.

Thats why I am wondering if the speed sensor could be faulty?