tmcmillan5

iTrader: (1)

I'm ready to order my new Conversion Harness with a reprogrammed E38 ECM and all related components. But now I'm being informed I can not use my existing external T42 TCM and will have to purchase a new one to match their reprogrammed (used) E38.

I don't recall this being the case awhile back and it's going to cost me another $ 125.00 that I hadn't intended on spending.

My engine is a 2007 LS2 w/the 4L70 trans from a two wheel TBSS.

Thanks , Tony

Project GatTagO

iTrader: (7)

I don't have direct experience with this, but it seems that the TCM can be programmed by itself....no? Hopefully someone will chime in with more concrete info.

Andrew

mOtOrHeAd MiKe

iTrader: (8)

2007 TBSS should have an E67 PCM with a T42 TCM. Both can be flashed seperately.

http://www.lt1swap.com/pcm_identification.htm

gofastwclass

iTrader: (2)

I have flashed several T42 PCM's with HP Tuners and had no issues. The E38 will communicate to the T42 via the CAN Bus and can be flashed together or independently.

tmcmillan5

iTrader: (1)

Ok so that means I should not have to buy a new TCM just have them reflash along with the e38 that they will be providing with the new harness ?

Thanks, Tony

L92 OLDS

FYI....The T42 TCM was used in a shyt ton of different GM vehicles. You can go to your local pick and pull and find them on many 2005-2014 vehicles. I pulled a few extras from a couple front wheel drive cars. Saturn, Malibu, etc. For those applications they obviously have a different tune loaded and are not plug and play. The harness pin outs also vary by application. Most people doing swaps don't realize they are a common item and pay way too much for them ($125 for used T42's) on e bay.

L92 OLDS

Here is a list of vehicles that use the T42 TCM. Maybe this will help someone some $$.

cpd004

iTrader: (13)

The E38 and T42 should be programmed together at the same time to ensure that they 'match' and communicate correctly with your throttle body and pedal. Whoever is providing the harness should be able to reprogram any T42 you send them and have it match whatever they are writing to your E38. At least the better harness providers can do this.

vortec4runner

Can anyone confirm that any T42 TCM can be flashed to operate a 4L60E? I have a T42 from a 2007 Saturn ION. I have HP tuners, but have never edited or tuned a TCM since everthing I have messed with before was a manual. I have been trying to research and I have seen people mention different operating systems for the TCM's. Can a Saturn ION T42 OS be changed to operate a 4L60E, and if so, how is it done in HP tuners? Thanks for any help!

PAloi

Im setting up a 66 Nova . 09 TBSS is the doner with 4l70e. I have harness tcm/ecm. Can someone please email me pin out for stock harness.
Also if I'm deleting the mechanical fan and running electric, is there a pin which needs to be installed?
Last any advice for cost effective best scenarios with mild cam upgrade ,stock intake and programming would be helpful. Thank you in advance.

LSX Power Tuning

iTrader: (4)

A T42 TCM is a slave module, it can be re-programmed to match your ECM. We flash them with SPS (GM Software) when we change them to something else but havent came across one we couldnt flash or make work.

Chevy 47

Looking for some help.

I have a 2013 LS3 that I have crammed into a 1947 chevy truck. I have installed a rebuilt 4L70e transmission to it. I have the original E38 ECM for the motor. I bought a wiring harness from Wiring Specialties who also took the original ECM and flashed it to run the 4L70e transmission. I bought a T42 TCM module online and had it reflashed and set to the LS3 vin number. The motor starts up and runs great. I can plug an HP Tuner laptop into the ECM and everything reads as it should. My issue is that there is no communication with the TCM. It does not even register in the HP Tuner. So, I have no speedometer and the transmission will not shift.

What or how should I go about getting the ECM and TCM to work together?