I'm wiring in a dakota digital SGI-5 box to convert the signal from my 94+ T56 to my 93 A4 ECM. The original VSS in my 4l60 sent a 4000 ac pulse per mile signal. I've found that the T56 is 17 pulse per revolution, but what does that equate to in pulse per mile so i can figure out my calibration app. Thanks for any help, i guess this is an ok place for this post. Move it if not, thanks

kevin

 

What's your tire size and gear ratio?

T-56 is 17 pulses per driveshaft revolution
4l60e is 40 ppm pulses per driveshaft revolution

 

tire size is a 275/40 17; outside diameter is right around 25", and gear ratio is 3.73. Would my 93 4l60 have the same pulse per revolution as the 94+ 4L60e?

thanks

kevin

 

I also have an SGI 5 in my car, and I just finished converting from a T-56 to a 700R4 trans. The reluctor wheel for the automatic has 40 teeth, so the speedometer will read really fast. All I had to do on my SGI 5 was press and hold the 'Down' button while driving. I held the car at a constant 65 MPH according to a GPS unit, and then held the Down button until the speedo read 65. I wired the SGI 5 right to the speed sensor, not just to the speedo wire, so the PCM sees the correct speed as well.

 

x28ke, for 1993 LT1's all VSS signals were a 4000 per mile sine wave for both T56 and 4l60 in 1994 they went to a 40 pulse per driveshaft revolution for 4l60E and 17 pulses for the T56. Are you asking how to convert the '94 T56 17 per revolution to the '93 pulses per mile. Figure your tire circumference in inches, divide it into the number of inches in a mile to get tire rotation per mile , then multiply that by rear gear ratio to get driveshaft revolutions per mile, then multiply that by 17 to get driveshaft pulses per mile.. I assume the box converts +5v Dc pulses to AC sine wave pulses. How do you plan on driving the speedometer and cruse control, in '93 they were fed directly from the VSS, not the PCM like 1994 and after lt1's.

 

thanks for the replies, with bobdec's formula i get that the VSS is putting out approximately 51,000 pulse per mile, which i need to convert down to 4000 ppm. If i can just get the speedo to work i'll be happy, I don't go on long rides very often. lets see if this works, thanks

kevin

 

I got it working, wired it in the signal wire right out of the VSS so the speedo reads and the cruise control works. I had to play around with the output type and switch settings to get it to read. THanks for the help!!

kevin