LY6/L92 into my firebird with m12 t56 e38 ecu. VSS Output problems

[LSX378]

Did you ever get the speedo to read correctly in HPTuners? I have a simlar problem. I just swapped a LY6 into my '76 GMC truck. I am running the Th350 tranny with a Dakota Digital VSS. I wired the VSS to the VSS High and grounded the other wire. I only get 158mph on the speedometer input on HPTuners. I got the same thing before I hooked up the VSS. I have no idea if the computer actually thinks I am moving but I really want to fix it so it does not think I am going 158mph.

Sounds like you have a truck tune in the ECM. Any idea of OS & VIN details?

[buddyholly]

Yes, this is a truck motor so it is pretty much a stock tune. The VIN is 1GCHC24K88E142144. 2008 Silverado if that helps. I have tried a bunch of configurations and get nothing for the speedo. It stays pegged at 158 even though I don't even see 158 as a max speed setting. I would not really care but it seems to get a lot of different info from different tables when the car is moving vs stationary. Either way I should at least be able to get it to read something other than 158mph.

[LSX378]

Yes, this is a truck motor so it is pretty much a stock tune. The VIN is 1GCHC24K88E142144. 2008 Silverado if that helps. I have tried a bunch of configurations and get nothing for the speedo. It stays pegged at 158 even though I don't even see 158 as a max speed setting. I would not really care but it seems to get a lot of different info from different tables when the car is moving vs stationary. Either way I should at least be able to get it to read something other than 158mph.

Honestly you might be better off time wise tracking down a tune that uses a hard wired speedo in the actual platform. Especially if the one you have (12622142) is for an auto trans. Trucks use some odd speedo scaling/routing and have been told that the overspeed speedo issue with truck tunes has not been solved.

What engine is the original tune for? Silverado 5.3, 6L, other?

[buddyholly]

The motor, wiring harness and ecm are out of the original truck. It is a 6.0L LY6. To the best of my knowledge there is no manual version of this motor. I was following this thread because liveaxles1 was having similar problems. I was looking at his tune before I had mine runnning and compared to other stock tunes his was missing most of the tranny options. I posted early on about how he managed this. Once I got mine up and running I realized my tune was the same way. Maybe there is something needed with the transmission control module that both of are missing. I think mine had a 6l80e behind it so there is zero chance of getting my hands on one of them since they are inside the tranny. The motor runs quite well as it is, even though it thinks is is running 158mph all the time..
Thanks for the reply, I appreciate any help I can get!

[kmkommes]

Has anyone figured this out yet? I have a 2008 LY6 with a Manual transmission (NV4500) and can not get VSS to work. I have it wired to pins 71&72.

[cam]

Has anyone figured this out yet? I have a 2008 LY6 with a Manual transmission (NV4500) and can not get VSS to work. I have it wired to pins 71&72.

Not that this fixes the issue of this thread but I run my speedo directly off the VSS out from the transmission itself. Its an Autometer Ultra Lite digital speedo.

I also ran a leg from the VSS to the PCM as well but I have still yet to get this swap in and running. Crazy year

[kmkommes]

I wanted to have it wired to the PCM for tuning purposes. Vehcile Speed is nice to know when logging data. It looks like there are provisions for DFCO (deceleration Fuel Cut off) and CFCO (Clutch Fuel Cut Off) but some of those parameters rely on Vehicle Speed working.

[cam]

To my knowledge this issue has yet to be "Solved"

[hicksport]

What did you do to the factory truck harness to get it to work, ie its looking for a park or neutral signal to start, and what all did you disable and or change to get it to start? I tried to open your tune file and it wouldnt let me says its outside of the bounds of the array? Im new to this so thanks in advance for any help and or suggestions.

[kmkommes]

I only spent about an hour on this tonight but I did make a little bit of progress. I do have plenty more to experiment with.

I have a 2008 LY6 from a Chevy Express van in my 99 Jeep Wrangler.
Build is here http://www.pirate4x4.com/forum/showthread.php?t=940551
I swapped the stock 4L80E for a NV4500.
The 4L80E used a seperate TCM (I think part # is 24239926)
I am using a early 90s Chevy Transfercase with a JB conversion slip yoke eliminator. (40 tooth per rev sensor).
My programmed tire rev per mile is 677.23

I was limited on my test capabilities because I was unable to tune tonight.
I dont even know if there is anything in the tune that will make a difference, if there was it would have been easier for me to find an answer to this.

All tests were done with ignition on and vehicle not running. I did not drive anywhere.

PROBLEM
I attempted to wire the VSS directly to my PCM. Pins 71&72. I have NO luck with this. VSS read a constant 158mph or something like that.

Test #1
I put a 40 tone ring on my cordless drill and spun it at 1350 rpm.
I measured the VSS frequency at that speed and got 900Hz
I wired the VSS to my TCM.
I checked the frequency output of the Rep TOS output and it was simply a duplicate of what I read with the VSS. 900 Hz
I connected the Rep TOS to (Pin 5) to my PCM vss (pin 71 or 72) and got nothing. I tried wiring it multiple ways but still got 158mph.
It appears as though pins 71&72 do nothing for Vechile speed with my Chevy Express tune.

Test #2
Partial Success (I was able to connect VSS to TCM and Vehcile Speed was sent from TCM to PCM over GMLAN)

Wired to the TCM were
Ground Pin 49
Battery Pin 32
Ignition Pin 31
VSS connected to TCM Pins 16 & 41 (VSS Low & High)
GMLAN was connected from TCM to PCM. TCM pins 6&7, GM LY6 PCM pins 27&28

Doing this I was able to read a vehicle speed of 0 mph with VCM Scanner 2.23 (I was unable to try any other version)
When I cranked my drill up to max speed I read a vehicle speed of 32mph. WAHOOO
I did a few calculations and that was the correct speed my computer was suppose to be running at my drill speed.
I spun the drill at multiple speeds and it seems to work great at speeds from 0 up to 32mph.

#s used for Calculations taken from current tune.
Tire rev per mile 677.23
Gear Ratio 3.73
40 tooth tone ring
Max measured drill speed 1350 rpm = 22.5 rev per second = 900 pulse per sec on tone ring = 900hz ( I did measure 900 hz on multimeter) = 32 mph : )

So what to do now....
I can leave TCM connected and will have vehicle speed but....
I do not actually have auto transmission connected so now I have to recheck my whole tune and make sure nothing elese is affected. The PCM does see the TCM and does think it is an Auto now. Does the PCM think it is in gear? Does it think it is in Neutral? Does it care at all? What is all being communicated to the PCM over CAN?

Further tests
I did connect a Kvaser CAN logger and logged all data while doing this test. I plan on decoding the CAN messages and possibly trying to create a LABview program to transmit a Vehcile Speed on to the CAN bus. This will narrow down the exact CAN message that the PCM wants in order to interpret Vehcile Speed. Long term goal could be to build a simple "VSS frequency to CAN message" device. I'm so busy I doubt that will ever happen though.

In the next week or two I will try to do some actual logging while driving. I will check my Vehicle speed against my GPS and also check different portions of the tun that rely on Vehcile Speed.

It's late, I'll try to edit all my mistakes in this post in the morning
I hope I didnt waste too much of peoples time typing all this. I needed to write it somewhere so I did not forget it. I mine as well share it.

Vehicle Speed can work my obtaining a TCM and connecting 7 wires. Ground,Battery,Ignition, VSS HI, VSS Low, GMLan Hi, GMLan Low.

[kmkommes]

I made a little more progress.

I called GM and the correct TCM for vehicle is 24252114.
It retails for about $146.48 but I see local salvage yards sell them as cheap as $35. Car-part.com let me find a couple for $15.
If you call a dealer to buy one you can use my VIN 1GCHG39K3 81117419, It is a 2008 LY6.

I have decoded message 000000F9 sent from the TCM.
It is an 8 Byte Message.
The TCM sends the transmission output speed to the PCM.
TCM is a 2 Byte Message starting in position 4-5 and message is sent as .250rpm/bit with 0 offset.
Example message would be 000000F9 8 FF,FF,FF,0F,A7,FF,FF,FF Time
That message = 1001.75rpm = 0F A7

Your PCM takes the Transmission Output Speed and calculates a vehicle speed given your PCM Tune.
I will try to verify this works by commanding multiple vehicle speeds and seeing how my tune responds.

I have succecfully controlled vehicle speed in HPtuners by sending that message with my laptop. I used a Kvaser Leaf Light & a Labview Program.

The TCM Sends multiple messages.
I still need to figure out what those are and if they are needed at all.

If someone creates a VSS to CAN translator using my info I would appreciate it. I dont have time to write code. It would probably take less than $15 in parts to build a device that does this : )

I did a search and the TCM I have is used in many different vehciles.
I would "guess" that any TCM could be used whether it is from a Chevy Van or a Chevy Cobalt. The TCM should be providing transmission output speed in both vehciles and your PCM does the math to determine vehicle speed by using rear axle ratio and tire size.

Thats all for today. Am I totally Off Base? Is there an easier way?
Another paramter that needs VSS is "adaptive Idle RPM" I would like to get this to work.

[tiresmokinV8]

Interested in this as well since I have a ly6/t56 swap in the works for my Sonoma.

[buddyholly]

My LY6 came with the 6l80e. Do we know how picky the e38 is about talking to body control module and transmission control modules? I wonder if any close TCM would work and be able to communicate with the ECU. In my LY6 truck motor I am running a TH350 transmission, but I am going to swap in a 4l80e that came out of my Chevelle. I could control the 4l80e with the E38, but I think I would have to run a different operating system since my operating system only has options for the 6l80e.

[tiresmokinV8]

So I've been talking to my tuner thats going to make up the custom wiring harness for my Sonoma that the ly6 is going in and he suggested that I use the e67 ecu since it supports the class 2 serial data wire that my guages need, which the e38 does not. Not sure if that might be your problem since I dont know what your firebird cluster runs off of.

[tiresmokinV8]

Heres where I was suggested the e67 ecu and why.

[tiresmokinV8]

Well we figured it out. We're going to build a harness for the ly6 engine and use a e67 ecu since it has the class 2 serial cable so my gauges and abs works. Found out that the '10+ Colorado, Canyon and h3 with the 5.3 is vvt and uses the e67 ecu so Im going to use that as a base tune. Not sure what you need for your gauges and what not to work.

[04colyZQ8]

mm any luck on the interface? I'm in the same boat, using a E40 auto tune, with manual trans. I wondering if maybe.. a 4000ppm signal is meant to go to pin 45 high signal from the TCM? It must be there for some reason? Its got to do something? I'd like to try a old DRAC module ise the 4000ppm out to the high signal pin 45?

[72oldsmobile]

was there ever a clear answer here?

i am trying to get the VSS signal into an E38 ECM while using a manual trans.

[buddyholly]

I never figured out a solution. I believe a BCM would be able to get the signal into the CAN network but I never got around to testing it.

[Grip]

I had a similar issue with a late 2007 LH6 from a Silverado (E38) swapped into and RX-7 with a T56. I had to keep the TCM and run the VSS wires through it to get a good signal. All that the TCM needed was the VSS in and out AND power and ground. No PND switch or anything else needed.