I hate to say this, but I went through all I could on the 1990 Mazda. There is nothing that I can identify to match what you are showing me. I will say that the black one in you hand seems to be for a relay. That looks like the pin layout for a relay.
Okay, since I'm not sure of the year and don't have specifics for the model you have, we are going to try something. I am going to provide four pics below. They are the engine control schematics for a 1990 B2600 4X2. Take a look through them and see if any of the wire colors or pin layouts seem to correlate with what you have.
In the manual, there are two pages of schematics for this. I cut each in half to make them readable when uploaded. I did overlap them so you could follow them easier. The first two pics are from page 1 and the last two are from page 2.
I wish there was an easier way. I hope you understand.
Let me know if anything matches what you are seeing in the vehicle.
Joe
Images (Click to make bigger)
Monday, April 13th, 2020 AT 6:03 PM