I have a 1999 4L60E from a 1999 Suburban that has been rebuilt twice successfully, and then had a TransGo 4L60E-HD2 shift kit installed that ultimately led to where it's at now with it's reverse and 1st only issue. I've been through quite a bit of troubleshooting and am basically at a loss
- Speedometer is working correctly
- Both shift solenoids have a resistance of 25 Ohms and click nicely with a 9v battery
- If my transmission control/PCM is unplugged completely it limps still in 1st gear (which to my understanding is supposed to be impossible, since both solenoids being off should be 3rd)
- You can kind of feel the transmission try to shift to 2nd barely when it's supposed to, and then stops "trying"
- Commanding gears with the trans controller doesn't change anything
- Using the gear selector/tree also doesn't get out of 1st/R
- Sonnax Corvette servo installed with just enough shims to allow the input shaft to still be hand-rotatable
- Nothing I've torn down so far has any wear, and there's been no odd noises coming from anywhere while driving
- TPS shows correctly in my transmission controller software, reading from about .5v to 3.4v
Based on what I can find out by other forums and such, this collection of symptoms seems to be a very uncommon one. It was working 100% before the shift kit install, which only had us replace parts in the valve body, but it was never able to shift out of first since.
I currently have the transmission out with the valve body partially disassembled. What should I be testing?