So when it is cool outside the speedometer works great. But when it gets hot outside it starts jumping all over the place. I replaced the sensor in the rear diff....any other Ideas?

Thanks

 

the sensor in the rear diff is the "exciter ring" it is used for your ABS, but when the ring is damaged it could throw off your speedometer, but to check the ring take off the rear diff cover and see if yours looks like this. http://www.cumminsforum.com/forum/at...le-rearend.jpg but if it looks fine then the sensor for your speedometer is on your transmission or transfer case, thats where i would check next!

 

Thanks, I just changed the rear end oil and did not notice anything, and did not find and metal in the bottom, so we will move forward now...

 

I had an 03 avalanche with a speedometer that didnt like the cold. you may need to replace the step gears in the speedometer. many dealerships do it, and it only costs around $150. Having said that, i sold my avalanche without fixing the speedometer, but thats what was recommended to me. just a thought
good luck