What wires is in the blue clip for radio wire harness?

[HeyItsKj]

I am working on an 85 Celica GT-S convertible and installed an aftermarket radio because the old unit with cassette tape and equalizer did not work. We were able to get a wiring harness that fits the vehicle’s plugs but noticed the the harness with the blue clip is not being used, which was being used in the old head unit. Does anyone know what wires goes to the harness? I looked again and noticed that the old head unit only uses two wires from the blue clip. Hope y’all understand what I’m getting at.

[danf]

The blue connector is for the OEM outboard amp and subwoofer.

[HeyItsKj]

I noticed that the blue plug on the stock radio end only used 2 wires. Would you happen to have a diagram or know what colored wires on the plug do?

[HeyItsKj]

From the head unit

[HeyItsKj]

Figured some of it out, we found what the two wires were for the front passenger subwoofer, which is the only thing the head unit was powering. The other wires showed in the earlier picture, still have no idea what its for. Turquoise with red stripe for subwoofer positive/Turquoise with black stripe was ground.

[danf]

I do have the electrical service manual. I have a GT-S which had the amp.

Pin / Colour / Desc
1 / Light Green-Red stripe / Subwoofer +?
2 / Light Blue-Yellow stripe / Power (Horn fuse)
3 / Pink / LH Audio Input
4 / Light Green-Black stripe / Subwoofer -?
5 / Red-White stripe / Audio Input Ground (from outboard amp to headunit)
6 / Brown / Ground
7 / Light Green / RH Audio Input
8 / Unused

2 Pins are for the subwoofer connection itself, 2 pins are for direct power/ground, and 3 are for signal. As an educated guess, it looks like the amp summed the left and right audio signals for its input source. Hence tapping the left and right channels and having one wire run from the amp to the headunit (this is likely a signal ground.)