I have a 96 Blazer 4x4 with a 4L60E. I put a new motor in it 30k miles ago.
I am having a trouble at speeds over 60 mph. I'll be driving along and it feels like a surge kinda. its intermittent and when it happens the tach jumps up a bout 200 rpms. I've been told it maybe a torque converter lockup problem. I took it to shucks and read the codes, but nothing. I;m not sure if there reader does transmission codes. Any help would be greatly appreciated.

Mike

 

it sounds like a slip to me. is the check engine light on?

 

It might be a slip,but its very quick and it doesn't happen under load. No check engine light, no codes with a obd2 code reader at shucks. I'm not sure if it could ready tranny codes.

 

200RPM just happens to be the approximate slip speed of the torque converter. Sounds like something is happening with your TCC circuit. It could be a wiring problem either outside or inside the transmission, or a TCC solenoid issue.

 

it happens around 2000-2300 rpm. amy way to test it?