VSS Speed Input required?

[Tech3sandcars]

I'm building a very custom Offroad vehicle with 5 speed sequential manual transmission, the transmission does not have any provisions for a speedometer. I have L83 with TSP stage 3, VVT lockout, no AFM, Corvette Intake, 87mm TB, etc. The ECM was E92 out of 2016 Silverado with automatic. After much findling around by my tuner and calls to Speartech it was decided that a manual ECM out of a 2016 Camaro or Corvette was needed, just could not get it to run right on the Auto ECM with no TCM. So the manual ECM was ordered, Speartech stated these Direct Injected ECM's really have to have VSS to run right. So the question is does anyone have experience getting the manual ECM to function well with no VSS input?
I do have a Haltech GPS sensor for my Haltech IC-7 dash but that is a 0-12v square wave output, my understanding is the ECM needs a VR signal that swings both positive and negative.

Any direction would help.

[GHuggins]

Most of the throttle tables are vehicle speed controlled, so yes on that part.

[Alvin]

Yeah its required. I had someone bring me a swap with no VSS and it wasn't workable.

No matter what it would try to pull the engine to an idle while driving. Even on the gas it behaved like they do when you neutral reving

[Tech3sandcars]

Appreciate the help, Dakota Digital makes a GPS device that will spit out the sine wave needed for ECM VSS, seems like others have ran into the same thing. Will report back when running.

[shonuff53]

I just figured this out myself. I bought a Corvette ecm and will tell you now that you don't need it, the L83 ecm will work. I have an fbody t56 and tried rigging a VR to hall effect sensor converter (ecm wants hall effect digital signal). You can use x2 pins 5(+), 8(signal), 21(-) for a hall effect sensor. Copy your trigger settings and vss rotations etc if you're using something functional. My converter did not work, however, it was actively reporting an output (reading 0 mph). I don't know if this helps but I set my tq MGMT to use calculated vss and set the DD tables similar to an LT4 in that it uses rpm vs vss (not mph vs vss). This alone allows my car to run right and not throttle hang. You could use what I did, it's an $8 chip, you just won't have any speed related controls. Search this: ‎ACS758LCB-050B-PFF-T and you won't even have to wire the current part in if you just want the zero reading. I'm sure any similar sensor will work. I tried this on both the Corvette MT and L83 auto ecm and works well on both and throttle hang gone completely. Drives great!

[shonuff53]

Note... There are a few VR to hall effect converters out there. I was trying to cheap skate it and use a current sensor to pick up VR pulses and output a digital output signal. The actual converters are ~$20 to $320. But you really just need a hall effect zero reading and you can do that with cheap sub $10 chips.

[Tech3sandcars]

Hmmm...Interesting, appreciate the comments, I'll do some research.

[Tech3sandcars]

OK, Dakota Digital device is in place and at least working at the pin of the computer (X2 pin8), you are correct gen 5 Camaro is hall effect input, found a diagram that shows that. The Dakota Digital device, GPS-50-2, has 2 outputs, one is square wave (ground switching open collector) the other is +- 6V sine wave (VR emulation). The Camaro input on pin 8 shows that it has a pull-up resister internally, match that to the ground switching Dakota square wave digital output and you get a nice square wave at the ECU X2 Pin8 (Checked it with my scope). Dakota device can be put into test mode and can spit out 8000 pulses per mile, they want you to equate your setting so the speedo reads 60 mph.

So now the challenge is to get all the Speedo and Transmission settings correct so I get a 60 mph Vehicle speed when the unit is spitting out the test signal. The online help documentation doesn't exactly match my settings in HP Tuner. Can anyone direct me to a resource to understand the settings? Maybe another thread?

Tire size 35"
Ring and Pinion: 4.63
1st: 3.09
2nd:2.14
3rd:1.59
4th:1.26
5th: 1.00

[Tech3sandcars]

OK, so I drew this out a little bit, been jacking around with my settings to no avail, shows "O"mph with my Dakota Digital in test mode (was showing 158 mph before this so something changed). My tuner put in a configuration for trans and speedo that he thought would work, still no vehicle speed registering in VCM Scanner. The only wild card I guess is if I have the right diagram for the VSS input, can only find the one and it matches other diagrams I have. Have also include tune file if someone can look at settings.

Dakota Digital & VSS configuration.jpg

GaryCorvetteEcu-DD-TM-EL.hpt

[Cazbah362]

Any updates on this thread?