Hello, I am not entire certain I'm asking the right questions or even posting to the right forum section for that matter. If not, I'm sorry, but didn't really see where these issues fit elsewhere. Anyways, here it goes. In an effort to be transparent, I am going to tell the story from the beginning and the progression of events as I know them.

I recently bought this pickup, it was not running at the time, I was interested in a project vehicle, the price was right and so on. The initial problem was the fuel pumps had gone bad and needed replaced. I was told the transmission was rebuilt recently, but needed a new solenoid block. I fixed the pumps, got it running, checked the fluids, changed the oild, coolant, etc.. Went to put it in drive and nothing, not D, 2, or 1. I had reverse, park and neutral. Rechecked the fluid at operating temp and was 1/2 qt. Low. Added the fluid and, as expected, no change.

Took the truck to a transmission shop. They pulled the tranny and gave me a list of problems, mostly with the front clutch pack and drum, valve body, valves, seals and an array of other problems. They provided the updates to the tranny, new TC and cooler, and at my request added a shift kit. They initially reused the original solenoid block stating its ohmed correctly. Upon their test driving it, it began throwing codes stating the solenoid block was bad. They replaced the block, relieving it of the solenoid code.

They test drove it again and had problems with it stack shifting; as to what gears this occurred, I don't know. They then said they would check line pressure, they state pressures were good. They state possible valve body problems, the state this is ok as well.

They then state it's an electrical issue. They test wires, stating they are all fine and the root cause is the pcm. I provide a known good pcm to them. They install it and tell me this corrected the issue of the shifting.

I pick the truck up today and drive it home, probably 3 miles, seems to shift fine and everything works correctly. I decide to drive it around and test it out, normal driving, nothing more than 45 mph. Drive it approximately 4 miles and it begins to shift differently. Start in first, shift to second correctly. Attempts to shift to third, shifts back to second, then back to third with limited periods of what seemed like neutral in between. I slow down and the truck returns to second without hesitation. Speed up and the problem persists, I manually shift to second and it responds appropriately.

I drive slowly back home, let it sit and cool, try it again, this time a mile or two at best. Truck presents with the same symptoms. Slowly accellerate to 2k rpm, shift to second, slowly accelerate to 2500 rpm, no shift to third, let off the gas, apply the brake, third gear applies. If I slowly let off and apply the gas, it would shift back and forth between second and third gears as desribed above.

The transmision is under warranty, but is there anything I should directly be asking this shop? It seems that they have gone through it and are at the point they are going to tell me there is nothing else to do. Although they haven't said this yet, I just get the feeling. Regardless, this problem also interests me. Is there anything I should check myself before I take it back? What do these symptoms present to the experienced and knowledgeable people of this forum?

 

Moved to correct forum.

 

Sounds like a bad PSOM signal train to the PCM.
But also could be a bad TPS.
You need to find out what codes you have in the CM part of the self-test.
Note the CM codes are read out after the KOEO electrical part and the separation code.
You may also want to take the plug apart that plugs in to the transmission on the passenger side and look for broken wires going into the plug.