htfsc

Just got everything running in the truck and I took off down the road just to see how things feel and the transmission doesn't shift. Its stuck in second or third not sure which. We put it back on the lift and couldn't make it shift with the tuner. Its reading speed and that's about it. I didn't buy the engine and transmission as a pair. The engine is an 07 and the transmission is a 08 or 09, hoping to verify which tomorrow. Anyone have any ideas? Could it be a compatibility issue?

1989GTA

Yep, a compatibility issue and the two are not communicating. It was in 3rd gear as that is the default gear. I would go with the latest software. On the side of the transmission there will be a code and you can date it that way. Another is take it to a dealer and let them put a Tech ll on it. There is a difference in the 07 to 08/09. I would upgrade the E38 ECM program to match the transmission as it appears to be of later vintage.

htfsc

So this can be done with software and not have to change the TCM or ecm? does the compatibility have anything to do with the speed signal? Because it does show a speed

1989GTA

You might have to change the ECM. Depends on the service number. If so that would be the easiest way out. You may be getting some communications. I just don't know. From what I understand is the 07 system is kind of by itself. 08/09 are similiar. 010 is different again. Best to use the same year.

ctd450

iTrader: (1)

I have an '08 LY6 mated to what I was told is a '10 6L80, if I'm understanding correctly, I'll have to update the '08 E38 PCM to a '10 OS?

Cutlass Convert

Yeah your 08 ECM is almost garaunteed to not work with your 2010 TCM. I also doubt your 08 ECM can be updated to a 2010 OS.

I encountered a similar problem except I had 09 TCM and 2011 ECM. My solution was to buy a 2009 ECM off of e-bay. I made sure to get one from a silverado 5.3 like my engine so I didn't have to take it to the dealer to get the OS flashed.

You could also swap the TCM, but they are much harder to find on the used market since they live inside the transmission.

htfsc

So i've got an 08 transmission. Does anyone know for sure if the 08 tcm is compatible with the 07 e38. Can I update the operating system on the e38 or am I sol, and need to get a new ecm.

1989GTA

I believe you need to update the 07 E38 to the 08 E38 operating system. As to whether or not you need a new E38 will depend on the service number of your existing E38 ECM. You can get them on Ebay for $200 and programmed for $300. What is the service number on your E38?

Cutlass Convert

I don't often find stories of people upgrading to a newer OS, that ends happily. Here is a cheat sheet of Operating Stystems and the ECMs that love them.

http://content.efilive.com/documents...ty%20Guide.pdf

htfsc

Service number is 12597121

1989GTA

Do you know what vehicles the E38/motor and the 6L80 transmission came out of?

I don't know if you can download the 08 program into the 07 ECM. Sometimes they will brick up and not work. The sure way is to get an 08 E38 ECM and download the right program into it or get one with the right program already installed. Plenty of them on Ebay.

On my vehicle I had a 07 Escalade L92 and a 2010 6L80. Of course that did not work. Eventually I bought a 2011 E38 ECM and had it and the transmission reprogrammed to a 2011 Corvette program. Works like a charm.

htfsc

Engine is out of 07 yukon denali. Transmission I dont know about, either a denali or escalde since it's an awd unit. What I'm thinking about trying is writing the vin off my brother's 08 seirra denali into the ecm. If it bricks the ecm oh well I'll be right back to where im at but at least ill know I need a new ecm.

1989GTA

That sounds like a plan. It might just work. If not I would use the service number off your brothers 08 and go from there.

htfsc

I've got an update. I got home this evening and pulled the truck on the lift just to double check the wires were right going to the transmission. Everything checked out good. I then head to my friends shop a few miles away to finish up the exhaust and walah, it starts shifting. Gets all the way to 6th gear and everything seems fine. So get done with the exhaust and start home and once again its not shifting. Anyone have any ideas of what's going on? I know now its not a compatibility issue.

Jones'n

It's a problem with how it is wired. I bet each time you pull the battery or unplug the trans, it will shift fine the first time after you start it again. Then when you shut it off, start it up again and go, it won't shift.
It's the wiring for the ignition power to the trans.

htfsc

I've checked all the wires and everything is the way it should be as far as the ignition, constant power and ground. The constant power is good and the ignition turns on as it should with the key. It does work right each time its unplugged. I'm just baffled on what could be wrong with the wiring.

Hart_Rod

iTrader: (3)

Check your tranny plug again. I know a guy who didn't have it plugged in all the way and was getting the same symptoms as you.