I have a 2005 express 1500 with 528000 miles that the speedometer will drop down randomly and then the ABS and brake lights will come on with warning bells. the truck runs ok but I don't know what this is. Its an original engine but the trans was replaced 325000. Any ideas?

 

How old is the battery? Is there corrosion on the terminals? Check both ends of the battery cables!

 

The battery is relatively new and the truck is serviced every 4000 miles, However the issue is not electrical. I believe the speedometer is controlled by sensors attached to the trans which I am replacing on Monday. I was hoping someone else may have experienced this.

 

but no not really.