Adding amp to 95 BMW m3

I want to install a JBL P180.2 into the stock stereo system. I'm going to use the speaker level inputs on the amp for the signals. I've also read that there is no need to tap into the remote wire when using the speaker level inputs. Is this true?

My questions:

#1. What harness? (there's 2 harnesses on the amp)

#2. What wires in the harness do i need to tap into?

#3. Is it best to tap into the front left/right speakers?

#4. What is the best wat to tap into the wires?

If you have done this before please help me out and give me all the info you can. I know this isn't difficult, i just want to make sure it's done right the first time. Any pics you can provide would be great. Thanks.

I'm adding the JBL 180.2 amp to power a sub.

Usually I tell people to use a separate external line output converter instead of the one built in to the amplifier, but the ones in the JBL BP amps like yours are actually pretty slick and when hooked up properly will sound awesome.  Plus, as you mentioned, with the high-level inputs of the amp being used there's no need to run a separate remote turn on wire.  Essentially this install does not even require removing the stock head unit, as long as you can tap into the rear speaker wires.

Anyways, the jbl bp amps use 4 sets of speaker level inputs, so that the bass will always be the same even if you have your rear speakers faded a bit forward or whatever;  because the amp is still taking the signal from all 4 speaker outputs it'll stay at the same level.  I should point out that they don't require all 4 sets to be hooked up, so if you don't ever fade the stereo from up front then it'd just be simpler to tap into the rear speakers' wires (Asssuming you're putting the amp in the trunk).

The main thing to remember is to make sure you have the correct polarity for the wiring.  That is, make sure that the positive speaker wire is hooked up to the positive input on the amp, and vice versa.  You can verify this by checking each pair of speaker wires with a multimeter for voltage, while the stereo system is turned on.  Positive voltage means that the wire touching the red test lead is the positive speaker wire; negative voltage means the wire touching the black test lead is the positive speaker wire.

OR if you don't have a multimeter you can use a AA battery and, with the vehicle's speaker wiring disconnected so as to not send voltage into the car stereo, touch the positive and negative terminals of the battery each to one of the speaker's terminals.  If the speaker cone moves away from its magnet (outwards) then the terminal touching the battery's positive connector is the positive speaker wire;  if the speaker cone moves towards its magnet (inwards) then the speaker terminal touching the battery's negative connector is the positive speaker wire.  Then once you've figured out which terminal is which, just figure out which wire goes to which connector and then use the appropriate wire for your connection to the amp.

Finally, as was said previously, you need to make sure you tap into the factory speakers that get the most bass sent to them.  Obviously if you have afactory subwoofer tap into those leads instead of speaker leads, but I was assuming you just had the standard stereo system and not the Harmon Kardon system.

Thanks for all the info.

I ordered  the JBL  P180.2 but it should work about the same as the BP300.1. I had to order the 2 channel P180.1 to get the power i need in 4 ohmes. I was planning on splicing the front left/right woofers but you sugest doing the rears. I do not have the HK system in my m3 as you assumed. Do you know much about the P180.1?

You can use either the front speakers or the rear ones; however, I mistakenly said that the 180.2 has the two sets of high level inputs, but in actuality it only has one set.  Just whatever you do don't use the RCA inputs and the high level inputs at the same time cuz bad things will happen.

Since it's not the harman kardon system I think all of the speakers in the vehicle get a full-range signal, and so as long as you don't adjust the fade control any, you can tap into either the rear or the front speakers and it will sound the same.

Umm I believe they make a BP150.1, BP300.1, BP600.1, BP1200.1, all of which are mono 1-ohm stable, bass only amps.  Also these are the ones that have the front and rear high-level inputs.  Then the P80.2 and P180.2 are two-channel amps with only one set of high-level inputs.

I've not heard of a P180.1 so I dunno if that was a typo?

Anyways, the 2-channel amps are actually a lot different than the mono amps because the 2-channel amps can only have a 4-ohm load when they are bridged.  The mono amps can handle a 1-ohm load.

How many and what brand/model/impedence subs do you have?

Sorry yes the P180.1 was a typo, i ment P180.2.

I have one Infinity 1230W. I was going to go with the BP300.1 but i needed 300w @ 4 ohms the P180.2 gives me 360w @ 4 ohms. The BP300.1 would have given me 300w @ 2 ohms the 1230W is a 4 ohm speaker. These are the reasons for me choosing the P180.2.

If you hook up a regular hi-to-low line output converter to the output wires from the factory head unit (BEFORE they get amplified by the factory amp) then yes you will definitely have problems.  Actually since you've been able to find out that it puts out a 4-volt preamp signal, you might as well just make an RCA cable to plug into the amp, and eliminate the LOC altogether.

You need to get a regular RCA cable and cut the plugs off of one end, but then you'll take those bare wires and just hook them up to the corresponding wires coming from the factory head unit.  (positive and negative for each speaker).

Just make sure that the wires you're tapping into coming out of the head unit are indeed unamplified signals because you don't want to be hooking an amplified signal up to your jbl's rca inputs....

I don't know what your plugs look like but these diagrams might help a little bit.  Also the wiring harness that plugs into the factory wiring (for aftermarket head unit installation) is the Metra 70-9195 and if you can't read the labeling on the wires in the pic, just remember the colors of the metra harness follow the EIA standards for function->color.  I know that the wires say they're for speakers but a lot of times if a vehicle also has a factory amplifier, they will just use the same harness as all the other vehicles but instead of going directly to the speakers it will run to the corresponding inputs on the factory amp.

If you're not keen on the RCA cable idea then it would probably be easiest for you to make your connections to the back speakers because not only is this going to be closer to where your jbl amp will be installed, but you have to tap into an amplified wire if you're using a LOC and you could either do that at the door speakers or the rear speakers so its up to you...