When you want to install or upgrade the stereo in your BMW 3 series, it can pay to do it yourself. Using this 325 stereo wiring guide can help you install an aftermarket radio yourself. This BMW 325 stereo install schematic can identify speaker wires and colors easily. Without taking your 3 series to a professional stereo installer can save you money, making your stereo install easy and affordable.
Today I’ll be covering the BMW 325 from the second generation to the present model. This 325 stereo wiring guide covers the year ranges from 1982 onward. No matter what kind of BMW stereo upgrade you are planning, this stereo wiring schematic will help. Quickly and easily install your BMW radio, amplifier or upgraded speakers using this wiring guide.
Second gen 325 stereo wiring 1982–1991
The early BMW 325 stereo wiring is simple and based around a standard single DIN layout. While this makes install simple from a hardware standpoint, there’s clear lack of illumination wire in this year range. You can either use a dimmer switch to install your BMW stereo or use the switched ignition signal from your steering column.
325 Stereo Battery Constant 12v+ Wire: Red/White
325 Stereo Accessory Switched 12v+ Wire: Violet
325 Stereo Ground Wire: Brown
The speakers in the 2nd gen BMW 325 are in the kick panels up front.
When you need to upgrade your BMW speakers in the back you can access them through the trunk.
Left Front Speaker Positive Wire (+): White
Left Front Speaker Negative Wire (-): Black
Right Front Speaker Positive Wire (+): White
Right Front Speaker Negative Wire (-): Black
Left Rear Speaker Positive Wire (+): White
Left Rear Speaker Negative Wire (-): Black
Right Rear Speaker Positive Wire (+): White
Right Rear Speaker Negative Wire (-): Black
Third gen 325 stereo wiring 1991–1998
One of the most popular year ranges of 3 series, the third gen is also known as the E36. There’s quite a bit in the way of upgrades to the E36 interior, which can make your 325 stereo install a little more difficult.
BMW Stereo Constant 12V+ Wire: Red/White
BMW Stereo Switched 12V+ Wire: Purple/White
BMW Stereo Ground Wire: Brown
BMW Stereo Antenna Trigger: White
Upgrading your BMW 325 stereo will require an install kit, as shown above. This will allow you to install a single DIN radio and the kit should have a plate that will cover up the rest of the opening in your BMW dash.
Much like the E30 before it, the first version of the E36 has the front speakers mounted in the kick panels.
Left Front Speaker Wire (+): Yellow/Red
Left Front Speaker Wire (-): Brown/Orange
Right Front Speaker Wire (+): Black/Red
Right Front Speaker Wire (-): Brown/Orange
Left Rear Speaker Wire (+): Yellow/Black
Left Rear Speaker Wire (-): Black/Orange
Right Rear Speaker Wire (+): Blue/Black
Right Rear Speaker Wire (-): Brown/Orange
The rear speakers in the E36 are likewise mounted in the rear deck. You can of course always access the speaker wires through your trunk.
Fourth gen 325 stereo wiring 1999–2005
The E46 is the fourth generation of the popular BMW 3 series. The changes to this generation of 325 include several upgrades to the dashboard. Needless to say that a stereo install kit is required. The BMW 325 stereo install is much easier with the right hardware and you can also upgrade just the stereo head unit.
325 Stereo Battery Constant 12v+ Wire: Red/White
325 Stereo Accessory Switched 12v+ Wire: Violet/White
325 Stereo Ground Wire: Brown
Although some of the 325i and 325is models also came with a navigation system, you can install a dual DIN stereo with the right install kit.
325 Stereo Antenna Trigger Wire: White
Left Front Speaker Positive Wire (+): Yellow/Red
Left Front Speaker Negative Wire (-): Brown/Orange
Right Front Speaker Positive Wire (+): Black/Red
Right Front Speaker Negative Wire (-): Brown/Orange
Left Rear Speaker Positive Wire (+): Yellow/Black
Left Rear Speaker Negative Wire (-): Black/Orange
Right Rear Speaker Positive Wire (+): Blue/Black
Right Rear Speaker Negative Wire (-): Brown/Orange
Use the 325 stereo wiring listing on this page to upgrade your BMW stereo. Of course if you don’t want to bother with a 325 stereo install, you can always opt for a FM modulator. Have any questions about this 325 stereo wiring schematic? Leave us a comment below and let us know!
