Volvo VNL 780 loss power and speedometer

ｉhad the same problem on freightliner，had to change ecu

 

I have had that speed sensor code come up on my dash a couple of times. Forget exactly what code it was, but it didn't affect my speed at that I noticed and went away on its own. I am not sure if it was the trans speed sensor, or an abs wheel sensor. Both times I think it happened after driving a while in rain and snow.

I will have to remember that if this ever happens to me. At least to get me somewhere to get it fixed the right way.

 

usually on volvos with i shift, if the speed sensor and abs sensor input are not reading the same speed for example abs light is on and not addressed it will throw a code for wheel speed correlation drop speedometer and it will not let you rev up past 1400 rpm. Need to address usually abs issues very little that can happen to speed sensor on trans. if issues are addressed speedo will work again. trans uses abs speed to shift and tailshaft speed only for cluster if those are not matching speedo going down is a way of telling you to FIX YOUR #### TRUCK.

Hope this helps understand it a little bit better.

 

A little I guess. I just know when it's come on I didn't notice any loss in power. But did recently discover I had at least bad injector cups too. Had bubbles in the return to the tank line. So could be I was already derated and didn't even notice it.

 

did you ever solve the problem, and if so, what solved it???

 

did you ever solve the problem and if you did what solve the problem? JayFlow116 because I did the same thing as you and I still have the same problem as you.

 

Nasriza. Where in Chicago u located?