So after diagnosing that my Infinity Amp was draining 1.4 amps with the ignition off, I decided to bite the bullet and buy a new single DIN head unit. I managed to locate the Infinity amp and with a bit of a struggle I removed it and binned it. I installed an 8 core cable from the Infinity amp location to the new head unit and got most of it working.
I traced the cables for the rear tweeters, rear mid-range speakers and front door speakers, but I can't locate cables for the two speakers mounted on the top of the dashboard. Anybody any ideas where I might get this information?

 

Yeah Alanc, I'll check when I get home but on the infinity amp you have two connector blocks, most of the speakers are on one of them, the other two speakers are on the same block as the power, from memory they're the right-most set of 4 wires but let me get my notes and send them to you later today.

 

Thanks Andy, that's what I was beginning to suspect.

 

No problem Alanc. I've traced and noted most of them, so here's the bits you need.

Right, I've got my notes, and connector1 (I class connector one as the one on the left of the amp when looking at it, which has the power supply also):

green/blue stripe + green/yellow stripe = front left top speaker
grey/blue stripe + grey/yellow stripe = front right top speaker

yellow+red stripe = +12 constant
blue+pink stripe = Ign +12v supply
White+purple stripe = CANBUS/Data circuit (caution!! Don't touch!)

Here's the infinity amp with just connector 1 still in place, so the top speaker wires are the rightmost on this connector.



Oh also Alan, not sure how much of a radio techie you are, so excuse if I'm preaching to the converted, but be careful how you wire all the speakers in. Series and parallel make a big difference to how the speakers are driven and how the head unit will handle the load. These infinity speakers are very low ohm (2 ohm is what I measured) which most head units won't cope long term very well. Therefore in my case my replacement head unit had front L+R and rear L+R, so because each channel had two speakers to drive I wired them in series (So top and bottom front left wired in series). This effectively doubles the ohm rating up to 4ohm which is more iwthin normal head unit tolerances but means that the volume/driven level is lower, potentially needing more wattage output to drive them, but on the unit I've got it can handle 4x45w so 45watt theoretical per channel (In reality it'll be lower).

Hope that helps and as always happy to help :-)

 

Thanks Andy, that's a great help. I'll take your advice about wiring the speakers in series. I didn't measure the impedance, I did look for a sticker on them but couldn't see anything so I just assumed they would be between 4 and 8 ohms.

 

Andy, have you any idea about the steering wheel controls, where do they terminate, do they work on resistance?
Alan

 

Unfortunately, like most things, they're all CANBUS linked, so rather than the easier ones that are resistance these send a message over the CANBUS network, so you've got two options really.
One is buy the stupidly expensive interface adapter that converts it to resistance, or open the steering wheel up, chop the wires and feed your own in.

At the moment I've not decided how to proceed, not sure if I feel up for a challenge of using an arduino/pi with canbus module and try to spot the sequence and use that, however since my car is dead in the water at the moment it's a moot point!

 

Incidentally, I think this could be why my amp was drawing 1.4 amps with the ignition off. I wonder if it also explains why sometimes I would lose all audio for 2 to 3 days but then it would just start working as normal.

 

Would certainly make sense, I'm trying to see which wires those are, I think those are the power/ignition feed wires so yes that would make things interesting! Good spot.

(BTW, bit late but you spurred me on to finish my write-up on it all at my website http://www.thebmwz3.co.uk/2017/12/ch...ifier-and.html)

The solder joints don't look great either, reflowing those would probably work wonders if you wanted to ever bother, although replacing probably been the best move.

 

In your blog you say:
That leaves me with two choices:
Run a wiring loom from the new head unit at the front, round to where the factory amp is, remove the factory amp and wire direct into the speakers. That way the new head unit completely controls the speakers direct and avoids the amp
Replace the factory amp with my own, still just use left and right (So new head unit couldn't control fader between front and rear) but it would be amplified output to the speakers.
At the moment I'm unsure which option to take.

I chose to do your first option. Using an 8 core alarm cable (yes I know that HiFi purists would shudder at the thought, but it's more than up to the job) It was easy to remove the two plastic door step trims to allow me to run the cable between the power amp and the new head unit. It was a 10 minute job.

Edit: I was going to add this as a comment on your blog Andy but decided to post it here in case anybody else if following the saga.