strange acting T42 4L60E combo with 4wd tun file

[harascho]

Hi there,

I still have problems finding a suitable 4wd T42 TCM tun file for my 2007 LMG (E38)4L60E (T42) drive train.

Today I tried some different T42 .tun files. Now it is even more strange to me.
I have three different tun files. One 2wd (OS 24235341 cal 24234634)
and two 4wd (1st OS 24235341 cal 24233141 2nd OS 24239036 cal 24237445) ones.

One 2wd and one 4wd even have the same OS. I compared them with EFIlive and they are 100% the same. Isn't that strange?
The other 4wd ( 2007 Silverado) has a slightly newer OS.

First I corrected the speedo seetings ( now possible with the new EFIlive update) in all tun files and then I tried a full flash with the first 4wd file. No success, no part throttle shifts, no downshifts. Then I tried the second 4wd tun file with the newer OS.. full flash.. and the same as before, a strange acting tranny.
Last thing was going back to the 2wd tun file ( this is actual the one my T42 came with..) and with that tun file the tranny shifts as it should.

For me it seems, as soon as I load a 4wd tun file something goes wrong??
Could there be some mixed up wiring ?? I don't remember a TCM connection which has something to do with the transfercase ? The only signal is the 4wd low signal to the ECM and that is wired correct.

So far I can use the 2wd tun file, I have 2hi and 4hi but 4low doesn't work, the tranny doesn't shift at all, except when the rpm reaches the limit.

Any ideas?

Harald

[gmh308]

Hi there,

I still have problems finding a suitable 4wd T42 TCM tun file for my 2007 LMG (E38)4L60E (T42) drive train.

Today I tried some different T42 .tun files. Now it is even more strange to me.
I have three different tun files. One 2wd (OS 24235341 cal 24234634)
and two 4wd (1st OS 24235341 cal 24233141 2nd OS 24239036 cal 24237445) ones.

One 2wd and one 4wd even have the same OS. I compared them with EFIlive and they are 100% the same. Isn't that strange?
The other 4wd ( 2007 Silverado) has a slightly newer OS.

First I corrected the speedo seetings ( now possible with the new EFIlive update) in all tun files and then I tried a full flash with the first 4wd file. No success, no part throttle shifts, no downshifts. Then I tried the second 4wd tun file with the newer OS.. full flash.. and the same as before, a strange acting tranny.
Last thing was going back to the 2wd tun file ( this is actual the one my T42 came with..) and with that tun file the tranny shifts as it should.

For me it seems, as soon as I load a 4wd tun file something goes wrong??
Could there be some mixed up wiring ?? I don't remember a TCM connection which has something to do with the transfercase ? The only signal is the 4wd low signal to the ECM and that is wired correct.

So far I can use the 2wd tun file, I have 2hi and 4hi but 4low doesn't work, the tranny doesn't shift at all, except when the rpm reaches the limit.

Any ideas?

Harald

Dont know that this exactly helps, but the two T42 files with the same OS, if they have different segment part numbers, behavior/compatibility could be potentially quite different.

OS 24235341 cal 24234634 (+ diag & system)
OS 24235341 cal 24233141 (+ diag & system)

The T42 has cal, diag, and system segments + the OS. The only way two controllers are perfectly identical, is if the OS and segment PN's line up.

Even though the cals my appear identical in an EFILive comparison, if the PN's are different, there is a very good chance something is different in there.

I dont recall whether you were running a 2WD or 4WD OS in your ECM???

Cheers and have a good weekend!

[VEGASROBBI]

Hi Harold,

Funny how we are fighting the same issues so far apart.

I think this transfer case thing can be more complicated than you think; depending on what setup you have.

I have been trying to get my trasmission to shift in 4 Lo also.

My powertrain came out of a 07' Siverado 4x4 with the "Selectable" Transfer Case option and the "M" code LH6 engine. There is also a "Manual" Transfer Case offered which is significantly different in terms of wiring.

In my case the 4 Lo signal is sent to the Transfer Case Module from a Transfer Case feedback sensor, interpreted, then sent to the ECM and TCM via the "accessory wake up" data wire. I'm not sure exactly what this wire does but the Transfer Case Module not only shifts in and out of 4 wheel drive, Hi, Lo, etc. but also controls the front and rear axles.

So , I tried to hard wire the 4 Lo signal into the ECM as if it were the "Manual" Transfer case, no luck. Maybe my calibration won't recognize those terminals.

It will up shift in 4 Lo at about 3,500 RPM, too high. My feeling is the ECM thinks it is in 2 Hi and doesn't need to up shift at such a low vehicle speed. Even though the engine is revving up the ECM is not smart enough(or programed) to compare engine RPM vs. VSS. It needs a 4 Lo signal.

I'm going to try and install the VSS in the transfer case adaptor, i.e. on the output shaft of the transmission. This way the ECM will see the 2 Hi vehicle speed all the time. This should make the transmission shift normal in Hi and Lo. I'm sure this is not optimized as if the ECM and TCM knew they were in 4 Lo; but I'm hoping it will shift in Hi and Lo. Fortunatlly my truck has a speedo cable driven speedometer off the Transfer Case so the speedometer should read correct.

Not sure my dilema will help you but there it is thinking. If could get the 4 Lo and AFM working my conversion would be complete

Robbie

[VEGASROBBI]

BTW I don't have the original Tranfer case (axle on wrong side) or Tranfer case module. If you do then it seems to be a software issue. Make sure your truck is wired for the Transfer Case option you have and the calibration matches that.

Robbie

[gmh308]

In my case the 4 Lo signal is sent to the Transfer Case Module from a Transfer Case feedback sensor, interpreted, then sent to the ECM and TCM via the "accessory wake up" data wire. I'm not sure exactly what this wire does but the Transfer Case Module not only shifts in and out of 4 wheel drive, Hi, Lo, etc. but also controls the front and rear axles.

So , I tried to hard wire the 4 Lo signal into the ECM as if it were the "Manual" Transfer case, no luck. Maybe my calibration won't recognize those terminals.

Robbie

Not sure if it helps, but to clarify, the accessory wake up line is an accessory fed power feed to the ECM and TCM (etc).

It is there in most cases to support "wake up" of low speed serial data when the key is on accessory, vs ignition on/engine running.

Cheers.

[VEGASROBBI]

Then the data is sent from the Transfer Case Module via the serial bus and we are back to the AFM issue.

[harascho]

Ok here is my setup. new 2007 LMG engine, E38 with 4wd tun file and OS
4L60E (out of 4wd suburban) and T42 ( came from a 2wd application).

I still use the '97 transfer case the electric push button one not the autotrac 4x4
I think it is a NP 241

I got that 4wd low signal wired correct to the ECM ( and double checked.) So the ECM knows what to to with the transfer case tailshaft VSS when in 4wd low. So far all should be fine.
I will post my tun files tomorrow (have to copy them from the laptop..)
I also have to check if there is any wiring difference for a T42 in 2wd or 4wd applications, as for now I don't see a difference there..

Patrick gave me a hint to log the VSS signal as TCM and ECM see it in low and high range.
Robbie, it's really interesting having the same problems in NV and Germany.

Here's a link with some pics of my swap:

http://s301.photobucket.com/albums/n...bum/?start=all

Harald

[harascho]

Hi folk,

I checked all the schematics, 2wd 4wd 4l60 E and transfercase (NP8 option)
So far I could not spot any wiring difference between 2wd and 4wd except that the ECM needs that 4wdlow signal to tell the ECM when the transfercase is in low range. That is exactly what is necessary for proper shifts in 4wdlow..

I have that signal but I have no shifts with a 4wd tun file in 2/4hi... Maybe I should load one again and check it in 4wdlow.. but that makes no sense 'cause it doesn't work in 2/4hi.

Here are the 2007 schematics, just in case...

[harascho]

the rest of the transfercase schematics

[VEGASROBBI]

http://www.chevyavalanchefanclub.com...1895.msg665705

Seems like we have conflicting information. According to Mitchell (not 100% trustworthy) there is no hard wire between the ECM, TCM and Transfer case module in the 2 speed automatic Transfer case.

Mitchell shows the LMG and LH6 having the exact same TC options. I can tell you my harness matches exactly to the selectable TC schematic and the only hard wire between the ECM and Transfer case module I see is the Accy wake up serial data wire. So, if that wire does not transfer data IM guessing it goes thru the computer data lines.

Only the manual TC shows the ECM getting the 4 Lo signal direct. I tried to wire my ECM this way with no luck; my VSS reads the same with signal or not.

For what it's worth here are the three diagrams I show for the LMG, I always trust factory diagrams over Mitchell, so if that is what you have take these with a grain of salt.

Robbie.