Installing FAST TCU...

[mac00x]

Hello all,
I have gone ahead and ordered the TCU from fast to shift the 4L80E after converting the 95 K3500 to MFI. I am going through the software and have to add in the speedo calculation stuff. tire size, 30.5, rear gear, 4.10, and then comes spedo pulse per mile....
I figured it up, tire has 662 revolutions per mile, times that by 4.10 rear gear, 2714.2. That is how many times the driveshaft spins per mile. Now the reluctor ring on the trans has 40 teeth, so 2714.2 times 40 would be the pulses per mile to the speedo. 108,568 ppm is what i came up with, am i right? well i go to enter this into the program and it will only let me enter a value from 400-100,00. What should I do, speedo will be off. anyone run into this? Maybe I should leave the factory wiring hooked up to the t/case to give MPH. any help would be great, thanks for your time
Chad W.

[gmctd]

Go to PowertrainControlSolutionsdotcom, get in touch with Russ - that's his TCU, so he can advise you best

[mac00x]

thanks called him and big help, i was trying to get the signal that the buffer reads, the factory speedo only needs 2000 ppm, the buffer takes the actual ppm and converts it and sends it to the speedo. Also what i was doing was more difficult than what he recomended. he said to just piggyback off the factory vss signal to the fast tcu, and leave the factory plugged in to keep the speedo working as factory. so there you go, all beter, i was overcomplicating things, thanks for your help....

[mac00x]

one more question, I have no clue where to find the RPM input i need for the new trans controller, I know the truck has a factory tach and is working so there has to be a way for me to tap into this right? any help would be great!!!!!

[More Power]

You'll need the 1991-93 engine speed sensor, which was used with the 4L80-E. It sits atop, and is part of, the oil pump drive assy, and is an 8-pole Hall-effect sensor. Just plug your TCM connector into the ESS, and you've got engine speed. :)

Contact http://www.peninsularengine.com for an ESS. They might even have a "like-new" unit for way less than new.

Jim

[Peter J. Bierman]

You can use amy pulsgiving thing on your engine, from the alternator if it has the correct pin for it or put magnets on the balancer and put a pickup on them or use the input shaft sensor from the transmission but that is not realy accurate but it works.
I think the factory tach comes from the alternator, you can piggytail on that signal and program the TCU to accept that signal.
Its all in the manual or online on the PSC website.

Peter

[More Power]

This pic shows the factory engine speed sensor mounted atop the oil pump drive assy.

http://www.thedieselpageforums.com/photopost/data/500/AMG506block.jpg