Hello all. So I have a 97 blazer with a 2000 4l60e trans, recently the SES light came on. A few days later I started getting a hard shift from 1-2, but only on drives of say 15 miles or more. Short trips it shifts nice and smooth. Fluid is full, does seem a bit dirty. This trans was put in about 8 months ago, have no idea the mileage as the guages were missing from donor truck. I have had issues with the ignition switch before causing shift problems and that was replaced 5 months ago. My research on here turned up tcc solenoid, or also possibly the valve body being worn. Any thoughts? if it's the valve body, I imagine that's an expensive fix?

 

The P1860 problem is electrical and simple in nature and can cause the P1870, so that is what to look at. If the problem turning on SES light is there all the time, shouldn't be difficult to diagnose or expensive to repair. Read this
https://blazerforum.com/forum/diagno...plained-28395/