Radio issues on 1999 Z3

[Rloun]

I recently purchased a '99 Z3 and the radio was a business radio and CD player. The radio code needed to be reset. I reset the code and the radio came on but no sound. I went to the trunk and found the HK amp had a melted harness attached to the amp. I also noticed the brown ground wire was showing a 12v+ when tested.
I suspect the radio is not original to the car and after removing the radio and disconnecting the harness, I have no 12v+ showing on the ground wire.
Does anyone know if these radios are interchangeable or have I found that the wiring patterns are different. I assume the next step is trying to find an original radio or change the entire system.
I did replace the amplifier and amp harness but don't want to melt these. I know the technology is much enhanced over the '99 model radios. I like the more basic classic look on the faceplate with larger buttons and less buttons I don't need...no Bluetooth, no phone hook up, just a straight head unit with a CD player. Could I use an aftermarket wire harness adapter and aftermarket headunit yet still use the factory amp and speakers or do I bite the bullet and replace it all?
I know, a lot of questions...thank you for any and all advice.

[bkirk]

I recently purchased a '99 Z3 and the radio was a business radio and CD player. The radio code needed to be reset. I reset the code and the radio came on but no sound. I went to the trunk and found the HK amp had a melted harness attached to the amp. I also noticed the brown ground wire was showing a 12v+ when tested.
I suspect the radio is not original to the car and after removing the radio and disconnecting the harness, I have no 12v+ showing on the ground wire.
Does anyone know if these radios are interchangeable or have I found that the wiring patterns are different. I assume the next step is trying to find an original radio or change the entire system.
I did replace the amplifier and amp harness but don't want to melt these. I know the technology is much enhanced over the '99 model radios. I like the more basic classic look on the faceplate with larger buttons and less buttons I don't need...no Bluetooth, no phone hook up, just a straight head unit with a CD player. Could I use an aftermarket wire harness adapter and aftermarket headunit yet still use the factory amp and speakers or do I bite the bullet and replace it all?
I know, a lot of questions...thank you for any and all advice.

The previous owner of my 1999 Z3 Coupe replaced the head unit and removed the CD changer and gave them to me with the purchase. I don't have the amp and ultimately I updated the aftermarket unit he used with a more modern one. If you are interested in the radio and CD changer, send me PM and we can figure something out, I had planned to list them on eBay.

[delvec]

If you decide to go with an aftermarket head unit you will need the Metra 70-8590 radio harness for a clean connection. Installed it in mine with HK amps...No problems. While your at it replace your OEM speakers.

[Rloun]

Update...the business radio is correct for the '99 z3. I plugged in the radio and hooked up the (new) used hk amp and amp wiring harness and again radio working, amp not melting but no audio. I took the old ohm meter and found the speaker wiring to be good but again the grounds in the amp harness showing 12v? The ground wires...ground to amplified antenna and 2 grounds to amp harness are showing 12v+ but NOT with the radio unplugged...Could the fault be in the radio or still a wiring issue from the radio to the amp. I suspect I'll be removing seats and carpet in the near future to trace the wiring...if wiring good, I guess there is an issue with the head unit. I would appreciate any thoughts or feedback...thanks!

[z3forlife]

http://wedophones.com/Manuals/BMW/19...g%20Manual.pdf

you could look here to check your wiring. First I'd verify the speaker circuits/voice coils are good. If you have a tone generator/tracker you can do a rough functional test of the speakers. See which wires melted once you reference the schematic. I’ve replaced everything on my M but my 99 I used the stock head to a alpine amp. At the end of the day you speakers are past end of service life and due for upgrade. They’ll work best with a aftermarket amp.

[Rloun]

I tested the speakers and found all to function. I can't wrap my head around the 3 ground wires showing 12v+ when the radio is plugged in. Must be sending 12v through power wire from head unit to amp and somewhere touching ground wire(s).
Thanks for the info. I'm going to trace the power and ground wires next. If no issues, I'll assume radio has the problem. Will replace system including speakers if that should be the case.

[djb2]

When you say "ground", what color wires and which pins do you mean?

[amancuso]

Ground on BMWs is a Brown wire, NOT BLACK.

[djb2]

Ground on BMWs is a Brown wire, NOT BLACK.

It's not that simple.. especially with the radio. Brown with a stripe is the 'negative' phase for the speakers, not ground, and the ground is sometimes black with a white stripe.

[amancuso]

This might help.