Is there a difference in LS1 and LT1 t56 speed sensors?

Heres the deal. I recently had my t56 in my 94 Z28 redone by a guy in Dallas and after several trips back to get this and that checked out I now still have the original noise (which a local trans shop says is most assuredly the input shaft bearing making it), my speedometer does not work, and I assume that is what is causing the stalling when I decelerate. Here is a cut and paste of what he described as maybe the problem.

"I noticed it(speedometer) wasn't working when I first drove it. I couldn't figure it
out, so I replaced the sensor with one out of an LS1 T56. It still didn't
work, then I noticed you had what looked like a switch wired in for
disconnecting the OD under the dash. I just figured the switch had been
off. Is that not a trip switch? Maybe it was off, and turning it on now
won't work because the sensor is different?



Does any of this make any sense to anyone else?
Can you disconnect the OD in a manual transmission in this way? Maybe I am completely overlooking something here.

 

Don't know about the LS1 vs LT1 sensor thing, but most definitely no vss signal will cause stalling on decelleration..

 

Isn't the VSS only on auto cars??

 

It would have to have some kind of speed sensor correct?

 

Both have vss.. it is also what sends the speedo signal to the car.

 

Ok surely someone knows if there is a difference. I dont want to have to call Autozone and get them to compare part numbers lol.

Brad

 

Not a bad idea.. my guess is that the shop probably severed the wire somewhere.. have you checked for that? I wouldn't trust them after what I saw from them on the post above.. too many mechanics have no clue.

 

Maybe by "OD" he meant "odometer"? Do you have any kind of switch under the dash that he could have seen?

Why not tell him to simply put the VSS from your LT1 back in, to eliminate any question? Does the PCM show any diagnostic codes for the VSS? It should, if it isn't working. Remember, the VSS output goes to the PCM first, then to the speedo/odo.... so its completely possible that the PCM is getting the signal, and the wire problem is in the connection from the PCM to the speedo.

And YES.... lack of VSS signal to the PCM can cause stall problems on "coastdown"... there is a table in the PCM that first cuts fuel completely on coastdown, then turns the fuel back on and keeps the engine RPM elevated until the car comes to a full stop. Lack of VSS could interfere with this part of the program.

Too many unanswered questions.

 

Well he is technically not a mechanic just someone who seemed to know what he was doing judging by many posts on the OTHER message board. I had never seen anyone complain about his t56 rebuilds. I have already had the car back down there several times and not only is the original problem still there I now no longer have a speedometer lol.

Originally a local trans guy told me it sounded to him like the input shaft bearing was bad and thats where the rattling noise underneath was coming from. I figured go ahead and have the trans redone since the car has 110k miles on it and this guy seemed very reputable and highly recommended and seemed very reasonable on the price. I guess it boils down to you get what you pay for. Reason I didn't have the local trans shop do it is they had never done a t56.

Brad

 

It seems that all transmissions from '94-'02 used the same "Sensor, M/Trns Output Spd", part number 12523306.

I'd still recommend he install your old one, just to eliminate any variables, though.

Dan

 

Good job on the part number..

You may want to look at the online junkyards you can find low mile t56s that will cost you less than a rebuild..