My speedometer don't work all the time, maybe a shorts in the system, Anyone knows where the speedometer cable/wire located on the tranny or transfer case on a 2003 expedition?

there is no cable! it opperates off a reading from the rear abs speed sensor - the infor is read by the abs mod. and relayed on the scp network to the cluster (hec module) which controlls the speedo - - are any warning lights on for the abs or engine light?

yes, the abs light comes on sometimes, how can i check the abs speed sensor? where is it located?

your most probably looking and a bad sensor - you can check resistance and most probably it will be open - normaly I just replace it.