The ecm module is located behind the passenger side kick panel. I don't know of an ecm relay.
That other relay should be the AC compressor relay.
The ECM on a 1992 S10 Blazer is located below the glove box.
We need to know what year the S10 is, it matters.
under the dash
Behind the passenger side kick panel.
Under the dash in the far right corner
does anyone know where the horn relay switch is on a 86 chevy S10?
The ECM unit for a 95 S-10 Blazer is located under the hood on pass. side.. Right in the open.
It is located behind the passenger side kick panel.
The idle sensor on a 1991 S10 4.3 can be located at the engine bay.
With a signal from the ecm it powers up the fuel pump.
Inside the dashboard, to the right of the glove box.