Hi all, I need some help diagnosing my 4l60e before I drop a lot of money on something I don’t need. First of all I am pretty technically inclined but the Automatic trans is my weakest area…

We’ll start off with some back ground information, I have a cammed ext cab 4x4 with 4.88 gears. Not a lot of stress on the driveline due to low torque and high gear ratios I would think. When doing my cam swap last year I picked up a lower end converter similar to a Trailblazer that stalled around 2800. Everything worked great for a while other then me wanting a bit more stall out of it. About 8-10k miles running the converter I noticed the lockup was pretty harsh like a 5th gear. I left the check ball in the end of the input shaft, no shift kit or valve body mods other then a vette servo.

This harsh lock up went on for a little while and I don’t really drive the truck that much since I have a fuel saving work car. Then it seemed like the converter then started getting harder to engage the lock up. I would have to throttle up the rpm and then the tcc would engage. Initially these things made me think the newly installed gear ratio was the culprit due to the mechanical advantage and lack of load on the system.

Eventually the MIL would light for TCC stuck off, I would clear the code and the tcc would then work. Once again this went on for a little while due to me only driving the truck for 30 miles a week to run errands. One day going to work getting on the highway sorta hard the converter would not lock up at all. I got the normal code and came to a complete stop on a exit ramp. Cleared the code on the fly and eased back onto the freeway with no tcc issues.

I finally got to the point where I didn’t want to clear the code any longer and bought a TCC PWM and TCC lockup solenoid. Decided to do a filter and fluid change since I just hit 30k on the trans and put everything back together. Well slipping the pan between the Longtubes Y pipe and the shift linkage both shift solenoids were unplugged about half way. I wasn’t able to tell until I went for a test drive which was about .5 mile total pulled the pan due to trans acting weird and MIL codes for the shift solenoids. I plugged them back in and took it for a drive now noticing the trans slipping pretty bad on any type of hard accel shifts.

I placed a order for a transmission about a month ago and it appears to be taking quite some time to get in. I called Rossler Transmission to see if they would be able to do a rebuild since they are a reputable company that is local to me. Unfortunately they are a bit to busy to take on my rebuild but the guy spent a good amount of time listening to my situation. He also pointed out that unplugging the shift solenoids would put the trans into limp mode and most likely not damage the clutch packs as I thought.

This all being said is making me think that my “budget” converter is causing the whole problem. Is there a way I could use my HPT to see if the trans is slipping clutches vs converter slipping on a test drive? It would save me lots of cash and down time but I don’t know if its wishful thinking at this point. Any Ideas/ help would be greatly appreciated to diagnose converter failure vs trans failure. I have also post a video on youtube of what the trans is currently doing with some moderate throttle applied.

Trans issue - YouTube