My mph reading on my digital dash reads slower than the actual speed. It is only accurate upto maybe 15mph. After that it starts to slow down. If it says 50mph i am actually doing close to 90 to 100 mph. I have had this problem ever since i bought the car 4 years ago. Scanmaster shows same readings as dash. What gives 
Car has been to a reputable transmission shop where i got the tranny rebuilt about 6 months ago. I notified him about the problem and to check the speed gears.I bought it back there to diagnose.
This is what he came to. Rear gears are correct (checked by spinniing rear tire and comparing it to the driveshaft). He took the tranny pan cover off to double check speed gears (orange and blue). He found that that convertor was not locking up. Ohmed out two wires and said they are not ohming out properly. He showed me some exposed bare copper on each of the two wires by the coil pack area (but they were still connected.)
His solution is to replace both lengths of wire (one leads to ecm). And if the car still does not show the right speeds to change the digital cluster. I do not know if this is the correct path to take. I thought there was some sensors outside the cluster that plays a role in the speed readings.
This thing has been driving me nuts. i think it is effecting my fuel economy big time. Can anybody help me?
Car has been to a reputable transmission shop where i got the tranny rebuilt about 6 months ago. I notified him about the problem and to check the speed gears.I bought it back there to diagnose.
This is what he came to. Rear gears are correct (checked by spinniing rear tire and comparing it to the driveshaft). He took the tranny pan cover off to double check speed gears (orange and blue). He found that that convertor was not locking up. Ohmed out two wires and said they are not ohming out properly. He showed me some exposed bare copper on each of the two wires by the coil pack area (but they were still connected.)
His solution is to replace both lengths of wire (one leads to ecm). And if the car still does not show the right speeds to change the digital cluster. I do not know if this is the correct path to take. I thought there was some sensors outside the cluster that plays a role in the speed readings.
This thing has been driving me nuts. i think it is effecting my fuel economy big time. Can anybody help me?
