Hey I'm new to the site, I'm just a teenager so I might not understand everything. Anyway, I recently installed a cheap radio into my 89 s10, after installing it I reaized that when I turn the headlights or park lights on the radio would automatically shut off and did not have power after either lights were turned on. Anyway after messing with all the wires I still had two wires that weren't connected to anything. The dimmer and illumination wires didn't have any wires to connect to the radio's harness. After pulling my multi meter out and playing with the wires I discovered that when the negative wire of my multi meter was connected to the ground of the radio, and the positive to the dimmer wire(with the lights on) the dimmer wire pulls -12 volts. Yes it actually pulls -12 I didn' have the pos and neg switched up. Anyway after coming home from work I went to turn on my lights and realized that my dash lights and tail lights wouldn't come on.I've checked the fuses and all the wires connected have good connection.I'm just wondering if anyone out there has installed a radio into a 1st gen and had similar problems. Thank you for your time, literally anythin helps at this point.

 

I'd temporarily unplug the radio from the rest of the vehicle's wiring harness and see if everything works again. That will tell you if something got damaged while the radio was wired up.

What did you do to identify the wires for the +12V and ground for the radio?

How did you make your connections to the new radio? Did you cut the wires between the OEM connector and the OEM radio or use an adapter to the OEM connector?

With the new radio disconnected and using jumpers, I'd hook up the power and ground to the radio but not the speakers and see what happens.

You might be on to something with the dimmer circuit also playing some role. Did the voltage at your meter change when you tried to change the dimmer setting?

Also, did you use the body of the vehicle for the speaker return/ground connection? That is bad to do.

 

​​

​​​​So basically I turned all power off to the truck for the install, I pulled the stock radio out and cut all of the wires off the stock radio harness. I found a wiring diagram for a 90 s10 and used that to wire the new radio, everything worked out fine, but there were two wires left over after the radio was fully installed: the dimmer and the illumination wire. So I taped those off and assumed that they weren't needed;but after discovering the radio didn't work with the lights on I knew they had to go somewhere. All connections are butt connections and everything is wired correctly except for the dimmer wire. The illumination wire doesn't seem to do a thing, it doesn't pull or give power. The ground is from the battery I believe because its from the stock wires. Anyway the dimmer switch doesn't change anything because the radio doesn't dim. I wish I knew what the illumination wire does and what the dimmer does because it'd be easier to troubleshoot. Anyway I'm gonna try to see what I can do today and hopefully figure something out. Again, anything helps at this point. Thank you