How-to Guide
How to Connect an External Amplifier to an Android Head Unit
Quick answer
Your front pre-outs are the white and red RCAs on Harness A, pins A4 and A6, and your rear pre-outs are the white and red RCAs on Harness C, pins C3 and C4. The amplifier turn-on lead is the blue wire on A1. Harnesses A and C ship with the unit, and you only connect them if you're running an amplifier.
What this gives you
You get four channels of clean line level out of the head unit, so an amplifier drives the doors instead of the internal output. On a 70 Series you either lose the music at 100km/h on corrugations or you can still hold a conversation with it on.
The same harnesses also carry a separate subwoofer output and a 5.1 centre channel, so the amplifier isn't the ceiling of what you can feed off the unit.
Before you start
- Harness A, the front audio pre-out and AUX harness, and Harness C, the rear audio pre-out and centre channel harness. Both come with your head unit.
- Four RCA leads long enough to reach your amplifier, and a thin wire for the turn-on lead.
- Your amplifier already mounted, with its power and earth run. The head unit end is the small half of this job.
- The battery disconnected before you pull the fascia.
Step by step
- Work out how many channels you actually need
If you're doing front only, that's two RCAs off Harness A. Front and rear is four, so you add Harness C. A subwoofer is a separate output again on A16, and it doesn't use any of these four.
- Connect the front pre-outs
On Harness A, A4 is the front left pre-out and carries a white RCA plug. A6 is the front right and carries a red plug. Run those two to the front input pair on your amplifier.
- Connect the rear pre-outs
On Harness C, C3 is the rear left pre-out with a white plug and C4 is the rear right with a red plug. Run those to the rear input pair. If your amplifier is only doing the front, skip this harness entirely.
- Run the turn-on lead
A1 on Harness A is the external amplifier control, and the wire is blue. Run it to the remote or turn-on terminal on your amplifier. Without it, the amplifier either never wakes up or stays on and flattens your battery overnight.
- Leave the speaker wires alone unless the amplifier is doing that speaker
The 16-pin main plug still carries the four factory speaker pairs. If your amplifier is driving a speaker, don't also wire it to the head unit output.
- Set the gains with the head unit volume high, not low
Bring the head unit up to about three quarters of full volume on a track you know, then raise the amplifier gain until just before it distorts. Set the gain against a quiet source and you'll clip every time you turn it up.
- Check balance and fader before you blame the wiring
If you're missing one side or one end after the install, check balance and fader on the head unit first. That's a faster check than pulling your dash apart.
If it does not work
- If your amplifier never powers up, check the blue wire on A1 is on the amplifier remote terminal, not on a permanent supply.
- If you get sound from one side only, check balance on the head unit, then check the white and red RCAs aren't swapped or half seated.
- If you hear a whine that rises with engine speed, that's an earth path problem, not the pre-outs. Take the amplifier earth to a bare chassis point rather than a factory bolt with paint under it.
- If you get no sound at all from the amplifier, confirm the head unit still plays through its own speakers. That tells you which one is at fault.
Worth knowing
Harness A also carries an AUX audio input on A5 and A3, white and red, so you can run a second source in without touching the amplifier wiring.
Still need help?
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