CHarris

iTrader: (5)

Will this work? I'm suspicious that this has been the cause of all my limp home mode issues on the transmission.

Per the Jags-that-run site:

A 4 pulse (4000ppm) sine wave signal is required by the 1990-1993 TPI, 1992-1993 LT1, and 1990-1993 Camaro V-6 cars.

A 40 pulse per driveshaft revolution speed sensor is used on 1993 and newer rear drive automic trucks as well as on 1994 and newer automatic transmission cars.

Do I have to swap to a 40 pulse per drive shaft revolution late model lt1 style sender to mate to a LS1 pcm? Or can I program for the 4000 ppm older LT1 style?

Speartech

iTrader: (14)

Although the 94-95 4L60E transmissions use a different harness connector on the VSS, it should still be the 40 PPR sensor setup that the LS1 uses. What year trans do you have?

CHarris

iTrader: (5)

I thought it was a 95 or 96... but I'm starting to wonder. It is definitely a LT1 - style... at least of that I can be certain.. lol

CHarris

iTrader: (5)

Assuming a 95 -or 96 4L60E...

What should the pulse tables be-- 4000 and 40?

Or the 1xx,xxx and 40 that came in the 2001 pcm?

Speartech

iTrader: (14)

As long as it is a 4L60E the trans has a 40 PPR reluctor on the output shaft, so the PCM doesn't know whether it came from an LT1 or LS1. The signal isn't any different between the two.

The PCM settings in the LS1 PCM should be like 128,000 ppm (ABS) and 4000 ppm (speedo).

355ss

iTrader: (9)

What would you do if it was a 93 4l60 with a 4000 pulse per mile?

CHarris

iTrader: (5)

Thanks for the info again, John. You're always very helpful.

I pulled out the cars existing VSS sensor and took a picture of it next to the new one. The old one (from in the car) has the gears. I may finally have found the source of all my troubles...



I'm guessing that I must change the VSS system completely to the the new style and get rid of the gear type all together. What do I need to do to achieve this? Do I have to change the transmission output shaft, too?

G-Body

iTrader: (4)

The sensor on the right is the old style 4000ppm. I think your transmission output shaft should be fine, but you will need the new style sender and a 40 pulse reluctor ring instead of the speedometer gear which is currently in the trans. You might be able to get away with a GM reluctor ring for a newer 4l60e, or if they changed the diameter of the tailshaft you may need to get an aftermarket reluctor ring.

Speartech

iTrader: (14)

Ahh yes. That is a unit for the 700R4 and is off by a factor of 10 for what the LS1 PCM is expecting. I think the shafts are the same, so you should be able to push the 40 tooth reluctor on and use the sensor on the left.

355ss

iTrader: (9)

I am having close to the same problem. I have a t56 with a gear drive conversion. I can get either 2000 ppm off of the speedo vss or I can install a 4000 ppm tailshaft vss. But it sounds like there is no way to compensate for this in the pcm programming? If so I guess I will have to get a new tailshaft housing, reluctor and vss.

Speartech

iTrader: (14)

With a T56, speed information isn't nearly as important as it is with a 4L60E. You could add an inline 4000 PPM speed sensor to yours and at least feed some speed info to the PCM. With that, you would only be off by a factor of about 4 since the T56 uses a 17 PPR reluctor. I think that would be sufficient for the PCM to know when you are in motion and when you are sitting still. With a T56 I don't think you care about much more than that.

CHarris

iTrader: (5)

Thanks again, John.

Does anyone know if the tailshaft housing can be removed and the gear removed and swapped out for a reluctor ring while the trans is on the car? I'm trying to figure out how much this is going to cost me

G-Body

iTrader: (4)

It depends how much room there is around the trans. I have never pulled a reluctor ring off, but it looks like they are just press fit like a speedo gear. So as long as you have the room to get the tailhousing to slide off you should be able to reach in or get a puller in there to pull the reluctor ring off.

CHarris

iTrader: (5)

Thanks for the good info guys. I really appreciate it. It cost me $350 today for two techs to work on it... but the VSS swap was a success. It would have teken me all day at home and then some so I guess $350 was a relative deal.

During the conversion to the 1995/1996 VSS system for a 4L60E we did hit two issues during the installation. First... the new 40 tooth reluctor hit the tail shaft housing. So we had to grind away a small notch to allow it to rotate freely. When that was done the tailshaft housing was installed and it was discovered that the new speed sensor actually hit the reluctor wheel. The end of the magnet on the sensor looked like this...

l__l

The problem was the two ends were hitting the reluctor and stopping it from rotating. So we ground the magnets down until it cleared the reluctor. It had to be ground almost completely flat. Apparently the later Corvette tailshaft must have slightly more offset for the VSS pickup to clear the reluctor.

So now it shifts, but it seems to be a little flakey on speed sensitivity from time to time. It will read like this.....

30...30....30.....15.... 30....30... 30....17..... 30.... .30....14.....30...30...30..

I'm not sure if that will be huge issue or if it is caused by the clearancing "corrections" from the above noted interefence issue. I might have to change the rear housing off for the exact part I need. I just don't know yet.

Im guessing I can rework the TCC lock and unlock setting to make those little hiccups in the VSS less annoying. At least I hope so!

Thanks again for the help guys! It would have been still sitting waiting for some attention if it hadn't been for your help!

Cory