Silverado E38 no turnover w/out main trans harness plugged in with piggy back Holley

[Chuntzu]

I have installed a Holley Terminator X Max on a e38 ecu/t42 tcu Silverado. The Silverado starts up fine with the key and stock key on ignition system when the main factory transmission plug is plugged in, but will not start without it being plugged in and the Terminator X Max Transmission harness plugged in. I have cleared, what I thought, were the checks with HP Tuners but still no engine turn over with the key and Holley Terminator X Max Transmission harness plugged in. The things I removed were starter fault checks in the os tab, starter diag in system general, no error report p1631, both vats disable and write entire. Still wont start without the oem harness plugged in. I am looking for any help to get the factory key to turn on the truck with out the factory Transmission harness plugged in. I presume there is a wire in the main transmission harness that needs to be powered or grounded to pass an ecu check, or I didn't clear everything in HP Tuners to get this to work. Thank you for any help.

[10_SS]

I have installed a Holley Terminator X Max on a e38 ecu/t42 tcu Silverado. The Silverado starts up fine with the key and stock key on ignition system when the main factory transmission plug is plugged in, but will not start without it being plugged in and the Terminator X Max Transmission harness plugged in. I have cleared, what I thought, were the checks with HP Tuners but still no engine turn over with the key and Holley Terminator X Max Transmission harness plugged in. The things I removed were starter fault checks in the os tab, starter diag in system general, no error report p1631, both vats disable and write entire. Still wont start without the oem harness plugged in. I am looking for any help to get the factory key to turn on the truck with out the factory Transmission harness plugged in. I presume there is a wire in the main transmission harness that needs to be powered or grounded to pass an ecu check, or I didn't clear everything in HP Tuners to get this to work. Thank you for any help.

you try setting Trans Type to manual in the tune? Then see if there are any Trans DTC's, and disable them.

[kevin87turbot]

Connect TCM connector pin 10 to pin 14, and pin 11 to pin 13 - this should complete the GM LAN circuit.

[Turbo370]

Did you ever figure this out? I?m in the same situation right now with my 2011 GMC Sierra.
Thanks

[castorjames]

Did you ever figure this out? I?m in the same situation right now with my 2011 GMC Sierra.
Thanks

In order to crank ECM needs Park/Neutral Signal. on the E38 i think it is orange/black stripe. if i remember correctly it needs ground.
If you remove TCM it will open the can bus circuit and will not talk to other modules.do as suggested above