The two black relay boxes under the hood of a 1993 GMC Sonoma are fuse boxes that control part of the electronic devices in the vehicle. One of the boxes also houses the battery below it.
Driver's side under the hood in the Black box
In a black plastic box under hood, there moy be more than 1 fuse and relay boxes
under the hood one of the black fuse boxes has a relay labeled "circuit opening relay" that's the one
Fuse/relay center under the hood
Under the hood, behind the battery theres a series of boxes, its the last black box.
On a 1995 GMC Sonoma, the starter relay is typically located in the under-hood fuse and relay box, which is situated near the battery. To access it, open the hood and look for the rectangular black box; the relay will be inside this box, along with other fuses and relays. You may need to refer to the diagram on the cover of the fuse box to identify the specific starter relay.
Most Sonoma's have the fuses and relays under the hood driver side under a plastic cover.
It is located on the firewall (under-hood relay center) on the passenger side of the car. I believe it is the smaller of the two black boxes.
It is under the dash with some wires plugged into it. At least that where it is on mine.
Most of them are in plastic boxes under the hood.
The heater blower relay on a 2003 GMC Sonoma is typically located in the under-hood fuse and relay box. This box is situated near the battery on the driver's side of the engine compartment. You can identify the relay by referring to the diagram on the cover of the fuse box, which indicates the specific location of the blower relay.
There should be 2 fuse boxes, a "fuse/relay center" located under the hood on the drivers side and another fuse panel located in the left side of the dash, the drivers door needs to be open to gain access to this one.