This morning lost drive with no indication that it was coming. There was no slipping no hard shift, nothing. Still have reverse 1st and 2nd with no issues. What the H#&%?

 

It's going to be difficult to help you if we don't know what you're driving.

 

Sorry, 89 Blazer auto 4 whl drive.

I am thinking that I have trash in the valve body, maybe. It couldn't be bands or plates because there was ablolutely no slipping. Just the all of a sudden outage.

 

I doubt that the valve body is at fault. It sounds like you have lost the 3-4 clutch pack and the transmission needs to be rebuilt.

 

Is your speedometer working right ? Mine did this same thing and it was the vehicle speed sensor . Try wiggling the plug around , its on the tailshaft of the transfer case ...........

 

at around 70 mph it will jump around

as far as the clutch pack wouldn't there have been some slipping to indicate a problem there?

 

This is an 89 so there are no electronics that have anything to do with the operation of the transmission with the exception of the lockup of the torque converter.

Most of the time what occurs is the TV cable is not adjusted properly and causes low line pressure. The 3-4 clutch pack isn't the best on the early 700R4 anyway and can smoke quite easily. With low line pressure, it is just a ticking time bomb. It likely was slipping a bit before finally going, but it doesn't take much to strip the clutch lining on already worn components.

 

Also I just confirmed that in 2006 the tranny was rebuilt