I replaced my TCI SF3000 with a Yank SS3600 several months ago. I had the TCI for three years DD with many trips to the track and zero issues.

I've taken the car to the track twice with the Yank. Both times the tranny has gone into limp mode on my first run. The DTC reported is P0502 - VSS sensor low voltage.

After the first run last night, I turned off fault processing for that DTC and P0503 as well. No more problems at the track (other than spinning terribly).

Tonight driving my car normally, the TC suddenly unlocked for no reason and only relocked over 70mph. Nothing like that has ever happened before. I checked for DTC's and there are none.

I turned fault processing back on for P0503 and reflashed. Drove it around a little and lock-up behavior seemed normal.

Anyone have any ideas? I'm concerned because I have to drive to Dallas on Wednesday (350 mi.) and unlocked would be potential nightmare.

 

You might have a damaged speed sensor,
It might have got bumped during the converter install ( output shaft is loose when the slip yoke is not in place and moving the output shaft to the side can crack the magnet inside of the housing) this will give a weak signal.

 

Definitely consider replacing the VSS as mentioned! I have seen them fail and cause several different issues, including TCC symptoms... and not be reported by the PCM as being defective!

g

 

You sure your fluid level is spot on?

 

Yes.

Funny thing is, the VSS code and associated limp mode have only occured after the first burnout at the track each time I've gone. It had been a month since my first trip to the track and, in between, no problems. Second time out, same thing. Then the strange lock-up issue.

Edit: Just found this on Impala SS site after Googling ...

Tranny goes into limp mode - VSS dropoff w/ Hi-stall converter. The rpms are too high, but VSS is showing no movement. Happens after a tire burning take-off. Doesn't store a code, will not throw a CEL (I've heard that it will store a code if it happens 3 or more times). Cure: Reprogram PCM for VSS dropoff --

I did have the code - but hopefully this is what's going on and the reprogramming will cure it.

 

Replace the $20 sensor like stated, because reprogramming probably won't help. I had a similiar problem a few years ago: https://ls1tech.com/forums/showthrea...problem+tranny

 

VSS problems are not caused by a converter. They arise from damage during the tranny R&R.

Fix it and you should be good to go. Be careful driving it if lock-up is acting up. You don't want to burn up the lock-up clutch. I'd program the car to not command lock-up if you drive it before your VSS is fixed.

 

Replaced it this morning and drove to Dallas without issues. We'll see what happens next time I go to the track.

 

Update: Because of weather and other reasons, tonight was the first night I've been to the track since replacing the VSS. Did the same thing - went into limp mode after the burnout on my first pass.

This problem is definitely related to the new converter ... I guess the only fix would be to turn off the fault processing as I had done before.