L92 6L80 combo reading 158 MPH

[tinroof]

Hello all. New to HP tuners, new to the forum. I hope someone will be willing to help because I know this subject has been beaten like a dead horse. The speedometer in scanner reads a constant 158 MPH whether going down the road, or sitting in my driveway in park. The transmission is experiencing random flares. I've driven it enough that it should have had plenty of time to relearn itself. And my tuner has tried several times to tune it out with no luck. He and myself believe the speedometer being off in the computer might have something to do with the flaring. I have read all the threads I can find on the 158 MPH issue, but they all involve people that have taken automatic ECM's/OS, and used a manual transmission. Well, all my stuff is matching(as far as I know), which is an E38 ECM, L92 engine, and a 6L80 transmission. It's in a 1969 C10, but as far a the computer is concerned, it's a 2008 Cadillac Escalade. The ECM is the correct part number for the application. The TCM I ordered from street smart transmission as a refurbished one. I gave them the same VIN that's in the ECM, and they programmed it before they shipped it. The wiring harness is from wiring specialties in connecticut. Is this a tuning issue, or a communication issue? I checked a few wires in the transmission pigtail, I've got power everywhere I'm suppose to. I've spoken to mechanics, tuners, everyone I can think of. Please help. Thanks in advance.

[Alvin]

Typically this is a ECM/TCM communication issue. Having the same TCM and ECM OS for the same OEM VIN is the first step and that sounds like you've already done that. So if your using 08 Cad Escalade ECM use the same for the TCM. Beyond that check wiring communication and battery/igntion for both specifically.

No codes I assume?

[tinroof]

No codes. So far I have checked pin 4 in the pigtail, which is suppose to be constant power to the battery, I?ve got power there. Pin 5 which is ground, It?s good as far as I can see. And pin 12, which is switched power, again I?ve got power there. What other wires do I need to check beyond that? Thanks for the response

[thorarinn]

HI I am having the same problems, both speedo and flair.
Same setup.
Have you had any results?

[blindsquirrel]

With no files posted to look at, no, I'd guess there weren't any results. Probably went elsewhere where people were happy to offer guesses as possible solutions and eventually got lucky by trying things at random.

Personally, I think having data to look at (tune file and log file and a clear description of the components involved) is a better way to solve problems, but maybe I'm just weird like that.

[edcmat-l1]

With no files posted to look at, no, I'd guess there weren't any results. Probably went elsewhere where people were happy to offer guesses as possible solutions and eventually got lucky by trying things at random.

Personally, I think having data to look at (tune file and log file and a clear description of the components involved) is a better way to solve problems, but maybe I'm just weird like that.

My new internet BFF LOL

[obthomas]

158 mph is the default for the E38 when it is not getting a VSS signal. With an automatic transmission the VSS signal comes through the TCM I suspect the VSS or the TCM.

[blindsquirrel]

I suspect it's impossible to say without being able to see the ECM OS & TCM OS which can't happen unless somebody posts the damn file when they have a problem like this.