Explain to me how factory AM radio is wired...

[SWEET7T]

When I went and pulled my power brakes and brackets, I found a factory AM radio (not worth much to me I have hacked dash, but maybe to somebody esle). How in the world is this thing wired

I got the pigtail with it, the factory speaker and brackets were still there, but they were such a pain to get to I left them. On the back it says [12V (red), SPK (green), GD (blk)]. 12V of course is pwr... SPK would hook to the pos terminal of the speaker, correct? So is the circuit completed by grounding the speaker to the frame? Or is GD the speaker ground, and the radio grounds throught the frame of the radio? I was expecting 4 wires, not 3.

I want to check and make sure it works before I try to sell... Thanks for the help!

[rage'nrat638]

I WOULD EXPECT....yes it grounds thru the frame just like 99.9%
of every thing else on these trucks

[SWEET7T]

yeah yeah lol.......... is the ground wire the speaker ground??? And the radio grounds through the RADIO CHASSIS FRAME?!

I'm used to seeing a wire to ground the radio, and 2 wires (pos & neg) for the speaker =4 wires.....

[avejoe]

I just bought an original AM radio for my truck but I have not installed it yet. Here's how I tested without installing it to make sure it worked.

Power to "PWR"

+ speaker to "SKR"

Power ground and speaker ground to "GRD"

Everything worked so I assume its right.

Hope that helps

[freezmcnally]

I have these. it's not obvious to me because labels don't line up.

Originally Posted by avejoe

I just bought an original AM radio for my truck but I have not installed it yet. Here's how I tested without installing it to make sure it worked.

Power to "PWR"

+ speaker to "SKR"

Power ground and speaker ground to "GRD"

Everything worked so I assume its right.

Hope that helps