Well - I figured it out. For those in the future - It is the Violet wire in the WHITE Radio Connector thats come out of the original HU, pre-bypass. In other words, the only wire not included in the amp bypass is the antenna wire.
1997 LX450 Stereo /Power antenna /Amp bypass
- Thread starter Durst
- Start date
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It's been about ten years since I bypassed the head unit in my son's LX450 and copied this thread to extend a harness. Last year, I bought a 97 LC and was amazed to learn I could just plug into a different connector behind the radio!
I just picked up another LX450 and had to re-learn all this info. Based on my research, this is still the best method to wire in an aftermarket head unit to an LX. I ordered the Metra 70-1761 kit, which includes two connectors. Because I'm such a nerd, I reviewed the EWD and found the following:
The original factory radio has two plugs going into the back:
R1 (plug A) is a 15-pin white connector that is receiving its constant 12V, accessory 12V and ground from the factory amplifier. That plug also sends 4 positive signal level outputs to the amp, which all share a common ground. Plug A also carries signals to the factory cell phone for audio and muting.
This plug is not really needed when you install an aftermarket head unit, unless you want to access the Violet wire on pin 8 for the antenna. I can't imagine there are very many power antennas still functioning!
R2 (plug B) is a dark gray 12-pin plug that just connects to the CD changer. Not useful.
The factory amplifier has three plugs:
S15 (Plug A) Gray 10-pin plug that provides 12V battery, 12V accessory and ground to the amplifier. These will be used to power your aftermarket head unit. It also drives the front speakers through the light green, blue, purple, and violet wires. This plug will mate to the 10-pin plug from the Metra 70-1761.
Pin 9 (white with green stripe) goes back to the rheostat for dimming. (I think this could be connected to the orange illumination wire on the Metra plug?)
S16 (Plug B) White 15 pin plug just like R1. This one supplies power and ground from the amplifier to the radio (weird). It also receives all the signal level inputs from the radio. This plug is not used with your aftermarket head unit.
S17 (Plug C) Gray 6 pin plug. This plug connects the amplifier's speaker level outputs to the rear speakers and the center console woofer. The 6-pin plug in the Metra kit will connect here and power the rear speakers. It doesn't have the pins in it for the woofer.
In short, buy the Metra 70-1761. Don't buy the 70-8112. It's designed to use the R1 plug to send signal level signals to the factory amp and will sound like crap with loud whining from the alternator. You will have to extend the harness from the Metra adapter by about 24 inches to make it reach from the amp spot behind the dash speaker to the opening behind the radio. That's two connections on each of 11 wires (battery, accessory, ground and 8 speaker wires) for a total of 22 splices. Do yourself a favor and use heat shrink solder connectors. They're more reliable than crimped butt connectors and much less bulky.
I just picked up another LX450 and had to re-learn all this info. Based on my research, this is still the best method to wire in an aftermarket head unit to an LX. I ordered the Metra 70-1761 kit, which includes two connectors. Because I'm such a nerd, I reviewed the EWD and found the following:
The original factory radio has two plugs going into the back:
R1 (plug A) is a 15-pin white connector that is receiving its constant 12V, accessory 12V and ground from the factory amplifier. That plug also sends 4 positive signal level outputs to the amp, which all share a common ground. Plug A also carries signals to the factory cell phone for audio and muting.
This plug is not really needed when you install an aftermarket head unit, unless you want to access the Violet wire on pin 8 for the antenna. I can't imagine there are very many power antennas still functioning!
R2 (plug B) is a dark gray 12-pin plug that just connects to the CD changer. Not useful.
The factory amplifier has three plugs:
S15 (Plug A) Gray 10-pin plug that provides 12V battery, 12V accessory and ground to the amplifier. These will be used to power your aftermarket head unit. It also drives the front speakers through the light green, blue, purple, and violet wires. This plug will mate to the 10-pin plug from the Metra 70-1761.
Pin 9 (white with green stripe) goes back to the rheostat for dimming. (I think this could be connected to the orange illumination wire on the Metra plug?)
S16 (Plug B) White 15 pin plug just like R1. This one supplies power and ground from the amplifier to the radio (weird). It also receives all the signal level inputs from the radio. This plug is not used with your aftermarket head unit.
S17 (Plug C) Gray 6 pin plug. This plug connects the amplifier's speaker level outputs to the rear speakers and the center console woofer. The 6-pin plug in the Metra kit will connect here and power the rear speakers. It doesn't have the pins in it for the woofer.
In short, buy the Metra 70-1761. Don't buy the 70-8112. It's designed to use the R1 plug to send signal level signals to the factory amp and will sound like crap with loud whining from the alternator. You will have to extend the harness from the Metra adapter by about 24 inches to make it reach from the amp spot behind the dash speaker to the opening behind the radio. That's two connections on each of 11 wires (battery, accessory, ground and 8 speaker wires) for a total of 22 splices. Do yourself a favor and use heat shrink solder connectors. They're more reliable than crimped butt connectors and much less bulky.