https://www.r3vlimited.com/board/ ICE installs, headunits, speakers, subs, amps, alarms, carputers, and everything else en Thu, 16 Apr 2026 17:13:55 GMT vBulletin 60 https://www.r3vlimited.com/board/images/misc/R3V.jpg https://www.r3vlimited.com/board/ https://www.r3vlimited.com/board/forum/e30-technical-forums/car-audio-electronics/10159457-89-convertible-sound-system-help Tue, 14 Apr 2026 19:07:01 GMT
I have an ‘89 E30 vert with the original BMW Sound System, however the PO made some modifications that I am trying to revert back to somewhat stock. The head unit is the BMW Alpine CM5908, which is paired with the BMW Blaupunkt QuadroBoost amplifier in the trunk. I believe the first owner (I am now the third owner) added a genuine BMW 12 disc CD changer, which is mounted underneath the convertible top storage area in the trunk along with the addition of a Zack Morris brick style hardwired mobile phone, the phone was removed by the second owner, but the antenna and coaxial wiring in the trunk are still present and need to be removed. The second owner added a giant subwoofer box in the trunk, which he kept as I have no need for, but left all the wiring in place. The sub's wire gauge was almost 3/4" in diameter, which was directly connected to the battery in the engine bay with a giant in-line fuse, then ran through the footwell firewall and then back to the trunk. I removed this wiring along with an air raid style horn that was in the engine bay with a sensor that detected if the car was being lifted, which triggered a blaring alarm, ask me how I know... it went off when I was removing the level sensor. Four of the six speakers are blown as the PO used to live in Vegas and cruise the strip, while the E30 was a low rider.

My plan is to resto-mod the E30 back to OEM+ (lots of projects to do...). As it's now spring and summer is quickly approaching I am taking my wife and children out more to cruise and grab ice cream and they like the creature comforts of music and not just the wind and exhaust like I do. I want to keep the original CM5908 head unit and have it converted to Bluetooth (most likely Cantaloupe) to keep the stock appearance and functionality. Since only two speakers are working I clearly need to replace all six, I've been researching speakers on Crutchfield as I am into music, but not an audiophile. I’m looking for good-to-great sound, not top tier bragging rights that wins awards. I would like to keep the speakers the stock sizes and not cut any sheet metal to increase their size.

Here's where I need help and I am becoming more confused with all the threads I am reading here on R3V and other BMW forums, the HU and/or amp must be in need of repair, why do I suspect this, because sometimes there is sound from the radio or cassette player which seems to be working okay with what life is remaining in the two speakers, then all of a sudden the system goes haywire and sends out alien signals, like a blaring high pitch noise that destroys your ears or a deep pulsing sound that is also loud and disturbing. Here is what I have checked and tried to do so far:

+ The original radio antenna grommet was falling apart, which I replaced with a genuine BMW grommet. I initially thought that the metal antenna touching the sheet metal body this was causing the sound frequency issues, but after replacing the grommet the problem still persists.
+ The ground cable from the hood to the chassis is still in good shape, are there any other grounds for the sound system that I should inspect?
+ I pulled the on/off volume control knob off of the HU and tried spraying some compressed canned air into the pot, then tried electrical contacts cleaner and spinning it to clean off any corrosion or dust. The problem still persists.
+ I pulled the amp out of the trunk and opened it up to see if anything looked unusual or melted, everything seemed fine so I reinstalled and tested again, the problem still persists.

I did notice that there is a screw with what looks like two grounding wires that were clipped and currently attached to nothing, which is screwed into the trunk wall underneath the amp, this did not look like it was stock, it was probably added by the PO when he added the bass cannon.

I am starting to think the HU or amp is faulty as they are almost 38 years old. Any suggestions?]]> eco325iX https://www.r3vlimited.com/board/forum/e30-technical-forums/car-audio-electronics/10159457-89-convertible-sound-system-help https://www.r3vlimited.com/board/forum/e30-technical-forums/car-audio-electronics/10159104-disable-low-beam-check-light Thu, 09 Apr 2026 13:00:40 GMT
Is there a way to non-destructively disable the low beam check light? I'd like to be able to re-enable it later on if I change course.]]> Chebyshev https://www.r3vlimited.com/board/forum/e30-technical-forums/car-audio-electronics/10159104-disable-low-beam-check-light https://www.r3vlimited.com/board/forum/e30-technical-forums/car-audio-electronics/10157789-yet-another-wiring-thread-ls-swap Fri, 20 Mar 2026 05:12:12 GMT Jazirex https://www.r3vlimited.com/board/forum/e30-technical-forums/car-audio-electronics/10157789-yet-another-wiring-thread-ls-swap