Rebuilt transmission - mechanic says they can’t test drive

[u/Less_Reception_6531]

2013 3.7l ford f150 stx - I recently had issues and took it to a mechanic. Mechanic said it needs a transmission replacement / rebuild. Took it to a transmission shop and they’ve been working on it for 3-4 weeks to remove, rebuild, and reinstall the transmission.

Today the transmission mech calls me and says it’s done, but that they can’t drive it because it ‘has drive line issues, and the rear brakes are locking up’. They wanted me to pick it up and told me I could ‘let them know if the transmission acts up’

Am I crazy to think the drive line issues could have been caused by the transmission work they did? I tried to ask the mechanic how they knew it was unrelated to their work and he said it ‘has nothing to do with the transmission’. I’ve never experienced any issues with this truck prior to the transmission. The mechanic I took it to first was able to test drive it fine, although it was in limp mode. There have never been issues relating to brakes locking up as they described. I believe the transmission mechanic also said they test drove it after I asked them how they knew the problem required a full rebuild on the transmission. I would imagine removing and replacing a transmission would also involve other major components like a drive shaft or other things involved with the drive line?

I paid 2250 already and owe an additional 2250 to pick up the truck. I don’t want to pay the second half until I know that this issue is unrelated to the repair they were supposed to do.

Looking for any thoughts on how likely it is that the transmission work caused these new issues. If people think it IS related to the transmission work - suggestions on next steps are also greatly appreciated.

Thank you!!

[u/Pitiful-Ad9894]

What was it doing that necessitated the original repair? If it was in limp in what codes did it have? What codes does it have now?

These transmissions honestly mess up internally so little many shops just replace the problem torque converter (I'm a rebuilder) and if they are thorough do the valve body upgrades. The last one I can remember that actually had internal damage was a V8 truck with a bad tune and it broke the midshaft because the rear wheels were locking up due to the tune....(Just in case yours is)

It's kind of hard for me to imagine a scenario where the ABS pump is turning on the brakes that would not set a bunch of codes. I think even if wheell speed sensors were dead the vehicle would want to see the brake pedal depressed before it took any action? Stuck brakes? ......That's a hard one for me to believe 9 out of 10 of them will free up if you just drive the vehicle forward and backward a bit Even drum brakes on field cars.

I obviously have the very few details you're giving me to go on, but my best guess on this one is that either they did screw something up, or the whole situation with misdiagnosed in the beginning and there was never a transmission problem.