Speedometer problem on T-56

[6spdLT1Bird]

I have a T-56 6 speed on my 95 LT-1. It seems the speedometer always displays half of what i am really going. Intersate reads 35mph, neighborhood reads 15mph. is this as simple as changing the vehicle speed sensor on the transmission? if so.. where is it? i think its on the passanger side of the tranny.
thanks..

[Jeff_in_Atl]

Did your car come stock with a 6 speed or was it an automatic that was converted to a 6 speed?

[6spdLT1Bird]

i'm pretty sure it was a stock 6 speed.. but i cant be positive.. yeah i've heard about the transmission only putting out half of the signal that the 6 speed does. the console still has the 6 speed gear pattern, and the guy i bought it from never said anything about a swap, he did say the tranny was rebuilt.

[TraceZ]

i'm pretty sure it was a stock 6 speed.. but i cant be positive.. yeah i've heard about the transmission only putting out half of the signal that the 6 speed does. the console still has the 6 speed gear pattern, and the guy i bought it from never said anything about a swap, he did say the tranny was rebuilt.

Do you have option MN6 on your build sticker?

[6spdLT1Bird]

i'm not sure, how could i find out?? is it somewhere on the car?

[Z Ya Later]

Yup. Open up your glove box and you'll see a sticker on the inside. Look through all the codes to see if you have MN6 listed as one of them. They should be in alphabetical order, which helps

[6spdLT1Bird]

i will definatley take a look as soon as i get back home.. but if it is the correct tranny, has anyone ever heard of a speedo misbehaving like that? i'm hoping i can just get a new VSS.. or is reprogramming the PCM a very difficult task to accomplish??

[Jeff_in_Atl]

i will definatley take a look as soon as i get back home.. but if it is the correct tranny, has anyone ever heard of a speedo misbehaving like that? i'm hoping i can just get a new VSS.. or is reprogramming the PCM a very difficult task to accomplish??

I have never heard of a speedometer doing that.

I have never heard of a the VSS doing that.

The only time I have heard of that is from the conversion.

However if someone just swapped the computer with one out of an automatic it would do the same thing.

It's not hard to reflash it but you need a cable to hook it to a computer which cost about $100. Here is the only place I know to get one http://www.akmcables.com/ . I bought mine from there.

You will need the code to reflash it (if that is what is wrong). I have the stock code for a 94-95 6 speed car.

Where in the country are you located at?

[Injuneer]

This is interesting..... this same thread was posted about a week ago on another forum. I gave him virtually identical info that has been offered above - its an A4->M6 swap, or the PCM has been swapped. I was the one who explained the differences between the A4 VSS output (40 pulses/rev) and the M6 VSS (17 pulses/rev). I also pointed out that with an A4 program, he would be getting an SES light and code for the missing A4 connections. Apparently he didn't give my repsonses and creedance, and brought the post over here for the correct info.

One last thought.... what is the output signal from the 93 M6 trannies? Were they somehow different than the later ones? Is it possible someone swapped in a 93 T56?

[6spdLT1Bird]

hey injuneer, yeah i'm that guy on Firebird nation that we had this same conversation.. i trust ur info, i'm just trying to figure out as many possibilities of what coudl be causing this problem.. the guy i bought it from did say that he had put a new PCM in there, so maybe a flash for it would be necessary. oh i'm located in Florida, but my car is at home in SC. i go home in 2 weeks

[Jeff_in_Atl]

One last thought.... what is the output signal from the 93 M6 trannies? Were they somehow different than the later ones? Is it possible someone swapped in a 93 T56?

The parts lists calls out the same part number for the speed sensor in the 93 and 94-97 M6.

[Jeff_in_Atl]

hey injuneer, yeah i'm that guy on Firebird nation that we had this same conversation.. i trust ur info, i'm just trying to figure out as many possibilities of what coudl be causing this problem.. the guy i bought it from did say that he had put a new PCM in there, so maybe a flash for it would be necessary. oh i'm located in Florida, but my car is at home in SC. i go home in 2 weeks

That sounds like your problem. You need a reflash with the M6 software.

There were 3 codes when I swapped to the M6 but of the 3 would light the SES light. They were still there until I reflashed the computer.

[Injuneer]

The parts lists calls out the same part number for the speed sensor in the 93 and 94-97 M6.

But is the reluctor the same # of teeth on a 93? There's something screwy about the 93's, but I can't remember what it is.

JagsThatRun sells a 40-tooth reluctor gear for the T56.

http://www.jagsthatrun.com/Pages/Par...luct_ring.html

[Z Ya Later]

But is the reluctor the same # of teeth on a 93? There's something screwy about the 93's, but I can't remember what it is.

JagsThatRun sells a 40-tooth reluctor gear for the T56.

http://www.jagsthatrun.com/Pages/Par...luct_ring.html

I thought the 93's didn't use a VSS? I thought it was a speedo cable to the PCM, or something older-tech like that. Not that I would be complaining about my tranny using the same VSS as the rest of the LT1 T-56's.

[6spdLT1Bird]

that is indeed the stock transmission.. the guy that bought it must have put the new computer but didnt program it correctly for the speedometer. i'm clueless as to how to reprogram. i've always worked on classics