Does anyone know where I can obtain a wiring diagram for the stereo, amplifiers and speakers in the 88 535IS. I have just purchased this car, and the previous owner had an after market stereo installed recently, which was apparently working the day before I bought the car. It is wired in to the original wiring through the amps and balance control switch. i'm trying to determine if there is overcurrent protection on either the amps, or in the speaker lines somewhere. Any help would be greatly appreciated...
I found this with some googling - http://www.bimmerboard.com/members/vtbimmer/BMW_stereo.htm http://pdftown.com/BMW-E28-1982-1988-Wiring-Diagram.html I can't speak for your car, but if it's similar to my '87 325is, there's the head unit, and a booster amp. Someone else hopefully knows for sure, but I don't think there's a specific overcurrent protection, just that the stock speakers had enough capability to handle the stock booster amp; at max volume, or near max volume, you'd get a lot of distortion, but, (having cranked my stock stereo any number of times), I never had a speaker blow. I imagine any speaker would blow if fed enough power, perhaps possible w/ some aftermarket setup. Having had the complete stereo wiring for an '87 325is in my hand, I didn't see anything in the speaker wires indicating any overcurrent protection. If there's anything there, it's internal to the booster amp or head unit, at least for my model E30. I would guess your car would be similar, but I don't know for sure. Apparently your radio stopped working?
The 88 had the "premium sounds system" which means tweeter pods on the doors, mid-woofer (4") in the kick panel area (with the built-in crossover) and component speakers in the rear. The system amp is in the trunk under the speaker tray. The amp had a wooping 15 amps with 10% Total Harmonic Distortion (THD). The original wiring uses the body ground as negative part of the circuit so it is not the best way. Your aftermarket headunit probably has more than power than the stock amp. Here is what I did: I re-wired the speakers, this means getting wires all the way to the back, and get rid of the factory fader. I did replaced the components in the rear speakers with Infinity 5-1/4" components. I also added an 8" shallow mount sub-woofer with a 300 Watt amp. I also have a Bluetooth capable radio with a USB port that I mounted in the glovebox. Here is the fiinal result: The button that's where the fader used to sit is the "Push-To-Talk" for the phone functions. The sub fills the lower frequencies that are lost with the small size speakers. Good Luck!
