Anyone got an OEM amp they want to sell me?

People sell broken stuff on eBay all the time, but since you now have two dead amps... Did you consider the possibility the problem may be elsewhere? Does the amp get power?

Of course it can be done. Swapping a relay should be a piece of cake if you occasionally use a soldering iron. But... Relays usually fail on the switching contacts, not the coil. I'm not saying the coil can't fail, but I'd first measure whether or not the new amp's relay coil actually gets power. If it doesn't, the problem is elsewhere and perhaps a lot more complex or difficult to find than a relay. You can measure the voltage over the coil with a simple multimeter.

You wrote in your second post the system sounds very soft with the old amp, but with the new amp it "works" after bodging the relay. If the speakers work normally with the new amp, the problem is obviously not in the wiring.

In case I misinterpret "works"... Do the two door speakers on each side produce any sound? If yes and of equal volume level as the other speakers, double check the measuring methods you used to determine the speaker impedance.

Did a previous owner replace the speakers with after market ones? Perhaps there are filters in the doors (definitely not stock) which may influence the measuring.

Do you at any chance live nearby another fellow E31'er with who you can do a quick swap of the amp. Or arrange something at an upcoming meeting. Just to be sure it's not the amp... Keep in mind there are two amps for the E31: The early and late model. You must swap with the correct one (you can't mess up - one of the plugs won't fit if incorrect).

If the door speakers remain dead, have a look at X256 and X257. Perhaps these plugs are not seated properly (although you'd have a lot more issues with the doors if that were the case). Otherwise you'll have to take the door panels off and have a look at what's inside.

Ah, the previous owner did probably mess with the wiring. That's an important given. Considering the E31 audio system is built around a 10-channel amplifier and most headunits are only 4-channel, it is very likely the previous owner did change the wiring in the doors too. If he did it properly, he should have added filters too - somewhere...

Since both amps give different results it's safe to assume at least one of the amps has an issue. But since there's now a strong suspicion the wiring may be altered, you'll have to figure that out first and fix it where necessary. It's kinda difficult to give advice on this. Download the ETM for your car (make sure it's the right year) and have a look at section 6510 which describes the audio system. Unplug all speakers (the plugs on the speakers in the footwells, the plugs on the rear speaker pods, X256 & X257 for the door speakers and the speaker plug on the amp) and measure each wire using the ETM diagrams. Also measure for connections of the speaker system that shouldn't be (for example, since the speakers are disconnected none of the positive speaker terminals may have contact with the negative/common terminal - a high resistance is not good, it should be open, no contact whatsoever). Boring job, but you'll get a good picture of what's changed to the wiring.

If the resistance is not very low (a few ohms at most considering the loss over the long probes and wire), or not a constant (for example increasing), there's not a solid connection. Increasing values indicate capacitors, which on its turn may indicate filters.

If all measures well, turn your attention to the doors (or start with this if you think the problem is most likely here). Before taking things apart, it's best to measure at X256 and X257. You can't unplug the speakers without taking the panels off, so pay attention to the speaker's impedance this time.

If that's all ok as well, the wiring is not the problem. Get a good amp. If it measures weird things you'll have to get the door panels off...

Btw, if you use a cheap digital multimeter, disconnect the batteries (just undo the common ground location) while measuring. Measuring resistance over a voltage source (because of accidentally probing the wrong pins) may damage cheap meters.

Really soft sound from the speakers could also mean that the speaker level outputs from the head unit are not connected to the amp.

If the head unit preamp outputs are connected to the amp you will get very low level sound from the speakers.

Nope, that's definitely not stock. Seems like a lot of cut wires. That will be a joy to find out and fix (sarcastic)...

How difficult is it to run new wires if you're not happy with the OEM wiring harness? Some people...

The wiring loom for the headunit may still be left unmolested!
Those cowboys obviously decided to go the no-matter-what-and-where route and hopefully missed the obvious

The routing of the audio wiring loom is inside the middle console and nowhere near the doors. It is laid down underneath the middle console and rear armrest, then into the boot through the ski bag and going left and right towards the amp, CD changer and speakers.

I´d assume that you will find the chop job very close to the footwell speakers and maybe even dangling OEM connectors where they used to be hooked up.

HTH, cheers
Reinhard

Zitat von NickF;65802

This is right under the steering wheel. My best guess is a speed sensitive volume control? Any ideas? It's stamped with BMW Nov 1990 a month before my car was built so i guess it's OE despite the dodgy looking wiring.

I'll have to pass on this one. I've never seen that unit before and have absolutely no idea what it's for... Is there a BMW part number on it? Can you show a picture with a bit more overview so I can see exactly where it's located?

I'm not sure why'd you want a speed dependent volume control (GAL) on the speaker outputs, as the E31 already supports GAL on the radio harness. All the radio has to do is support it. Any good headunit does.

Anyhow, I'm quite confident my speaker wiring comes nowhere near the steering wheel, so I don't know why yours should...

Zitat

I downloaded the ETM for my car, but it looks very thin on the ground for the radio, just power not speakers? I'm looking at section 6510.0 is that right?

As far as I know section 6510 is the stereo system in all editions of the ETM. That's of course not limited to just the speakers. Just scroll down from that page to pages where you see speakers. For example, in the '91 ETM the speaker pages are 6510.0-1 (left front), 6510.0-2 (right front) and 6510.0-3 (rear). The speaker wiring is complete. If you don't see it on the diagrams, it's not supposed to be there. Make sure you read from the right diagrams as some years have more than one wiring diagram because of updates during that year.

This may be the control box for that very early radio remote (came with a key fob).

Here is a picture of the early remote control module incl accessories:

Allegedly this lives somewhere underneath the steering column next to the 3 control units (GM, LKM, EKM).

On second thought - with wires going everywhere ncluding the engine compartment it may also be an ancient burglar alarm control unit!?

Cheers
Reinhard

Its shape is different Reinhard... It's not the old remote control box. A burglar alarm is a possibility, but why would you route speakers to it? To prevent the thief from listening to the radio?

Btw, I just realized Nick has a UK spec car with the steering wheel on the wrong side. So when he mentions a module on the driver side, it's on the passenger side for our cars. I must add I really don't know how different RHD cars are from LHD on the wiring front. I've never worked on a RHD E31.

I do recognize the independent ventilation relay module on Nick's last picture (the box with the white text on). This module is on the passenger side of LHD cars (so it's not near the EKM, LKM and GM2). But I don't recognize the thing above it. Is this the module you mean, Nick? Or is the acual box hidden behind it? On your last but one picture I see a red and white wire entering the box, but on the last picture it seems as if the red and white wires (which appear to be heat shrink tubing) go over/behind the black box. Well, to be honest the pictures are a bit blurry, vague and hard to interpret ...

The BMW part number would be really helpful (well I hope)... If the module you mention is not the one visible in your last picture, can you give the part number of that box too? Just wondering what it is.