5 volt reference signal

On my 2014 chevy silverado engine which has a converted harness to engine and transmission stand alone. I have all of my ecm wires requiring voltage and all of my grounds in place. I have this harness on my table checking circuits with ecm powered and grounded. No sensors hooked up. I have tried 3 different ecm's and no 5 volt reference signal. I also at one time had the harness on my engine completely wired and no 5 volt reference. The 3 ecm's all have Vatts still active. Would the Vatts prevent a 5 volt reference. Need help!

in my experience vats disables fuel pump and starter. I’d recheck powers and grounds while the unit is plugged in.

If still no 5v ref then you have something pulling it down or a bad module.

I agree with John. I have never seen anti-theft kill 5 volt ref.

I don't know if this is the BEST route, or not, but desperate times call for desperate measures. I think I would snip the 5 volt ref wires, one at a time, at the ECM connectors (leaving plenty of room to spice them back together). If the wiring harness is, internally shorted, when you snip the shorted 5v ref wire, the 5v ref should return on the ECM Connector side of the snip, and the rest of the 5v ref circuits. The part I don't like about this is that it looks like there are 9 different 5v ref outputs from the ECM. Most of them will be the same circuit INSIDE the ECM. However, looking at the schematics, it looks like this vehicle may have two, separate, 5v ref circuits, internal to the ECM (wht/red and brn/red).

Connector #1


Connector #2


Connector #3