Ecotec E37 "Unable to detect the vehicles diagnostics protocol"

[CaffeinatedGearhead]

I am having issues with reading the vehicle with an error saying "Unable to detect the vehicles diagnostics protocol"

Background: I have a 1997 Mazda Miata that I am swapping in a 2.4L Ecotec engine from a 2009 Pontiac G6. I swapped in the stock ECU (E37) as well as the stock wiring harness. I went ahead and stripped out everything I thought I didnt need

The OBDII port has
-CAN HI
-CANLO
-Signal GND
-Chassis GND
-12V+

Initially, I only had 120 ohm resistance between CAN HI and CAN LO so I went ahead and added a resistor at the end of the CAN wires resulting in me reading the desired 60 ohm

The 12V+ port reads the desired 12V and both grounds are good.

We checked that the power wire going to the ECU is also getting 12V power, which it is.

We disconnected the aftermarket radio to remove any potential interference as well.

My MPVI3 is new out of the box so I went ahead and updated the firmware and resynced it a few times, still with no luck

Any advice would be great! This is our first time doing an engine swap and our first time using HP Tuners

[gtstorey]

Did this originally have the low speed lan wiring going to the obd port?

[CaffeinatedGearhead]

Issue resolved: I missed a wire that originally goes from the BCM to the ECU to give it 12V power when the car is in RUN mode. I had everything else other than that one wire!! I also did another firmware update per HP Tuners instructions. Everything is working as it should, for now

[CaffeinatedGearhead]

Yes it has the GMLAN (SWCAN) wire going to pin 1 on the OBD port.