Two steps back, one step forward

I've been plugging away at getting this car back to its original standard. A large part of the problem in getting it done in a reasonable time frame is waiting for parts to be delivered from Latvia - and then having to wait longer because I realise I need more parts. They say measure twice, cut once...

So I started plugging away at my checklist. Some things I know will be complicated, such as the roof, and other things will likely be simple and a degradation issue - like the wiper fluid level low warning on the OBC (not mentioned in previous post). After spending a day or so trying to work out where the factory amplifier was (and Google not providing clear answers), I decided to tackle the wiper fluid level low warning on the OBC. I popped the bonnet, and found the reservoir was about 70% full. I filled it, and continued to get the warning. After removing the reservoir and having a further look, I discovered there was a sensor -  it appears to be a moulded plastic air-filled float that carries a metallic magnet (it was rusted), that when in the full position triggers a reed switch. I'm not sure whether it's a normally open or normally closed reed switch, but it doesn't really matter - a bit of tape to hold the magnet/float against the top of the reed to emulate a full signal resulted in disappearance of the error. So, looking at the float, I see that the space that should be full of air is full of water - float does not float. I zip tied the the magnet/float against the reed and reinstalled it. I prefer to have a full array of functional sensors, but having trained as a motor mechanic previously, I think I can keep an eye on my wiper fluid! Plus, the sensors (61311388578) are $50 AUD new, which is half the price of a nice OEM leather gear knob. I plan to drill into the float and drain it later, then reseal it with an epoxy, like Araldite.

Factory washer fluid reservoir sensor. Common to a few models.

Yesterday I started looking into finalising something that's been bugging - no sound from the stereo. My research had lead me to believe that then late model convertibles had a 10 speakers driven by an amplifier from factory - I discovered the amp behind the rear seat on the driver's side. I decided, without really looking into it, that because the previous owner had installed an aftermarket head unit (Kenwood KMM-BT303), the OEM amp had been "over amplified", killing the 5x TDA 1552Q 22Wx2 internal amplifier chips. How do I know this? Well, I found someone on Facebook wrecking a convertible, and I bought a replacement "known working" amp for $36. While I waited for it to be delivered, I decided to see if I could see any obvious faults in the original amp, such as swollen capacitors or melted traces. As it turns out, the PCB and its components looked perfect. My crappy electronic engineering skills told me that perhaps two of the diodes on the power circuit had been over-volted (and thus allowed current to flow both ways), but I wasn't convinced.

The replacement amp arrived today, and after eagerly installing it, I was pretty annoyed that it didn't work either. The story from the previous owner was that it "just stopped working one day. And I have the receipt for the new head unit". So I decided to get the multimeter out and check what sort of voltages were floating around - as after very thorough review of the 10-speaker system wiring diagram, I knew that the amp was always receiving 12v+ via fuse #9 (20A), as was the radio - as this fuse can't be blown because a) the radio works, and b) it wasn't blown (the radio and amp receive 12v+ via a tied line from fuse #9). The reason the amp doesn't drain the battery constantly is because of the white amp turn on wire, as triggered by the radio - I guess it either switches a small SMD relay in the amp itself, or possibly uses a diode as a relay. Anyway, when testing the voltages at the main 12 pin connector on the amp - I found that the thick brown wire (pin #3) is earth, and is always earth. The thin white wire (pin #2) is the amp turn on wire, and has continuity with the equivalent at he back of the head unit. It receives 12v+ when the ignition is in ACC or ON. Pin #1, 12v+, gets 0v+ when the ignition if OFF, and only 1.5v+ when the ignition is on. Ah!! This says to me that the amp is receiving insufficient power to turn on, despite being told to turn on - and it's probably because of damaged wiring between the junction between the head unit and fuse #9, and the amp. I confirmed this by running a bypass directly from the battery 12v+ terminal to pin #1 on the amp, and music played first go. Glorious! Rather than pull the car apart chasing the damage to the loom, I decided to make the bypass permanent with a ring terminal, inline fuse holder and 20A fuse, and equivalent gauge wire. After turning the sound up a little, I discovered the rear left speaker (well, one of them) has some crackling - a new set of speakers will be on the cards eventually. Possibly the Bavsound kit.

Bypass: earth from a chassis mounted bolt, amp turn on as-is, 12v+ from the battery 12v+.

Sound, in the first instance.

A bit of progress is always welcome.

Showing the bypass, and the sealed wire cut from the factory loom.

As for the antenna - I received the OEM antenna rubber seal, and wasn't satisfied with the fitment. After fiddling around with it, and removing the antenna module, I noticed that after removing the the large nut off the module, the wire beneath it was broken (difficult to explain). I decided to disassemble to module to try and repair it........and snapped the whole thing in half. Damn. Cheapest is $177 AUD, again from Latvia. As I listen to radio very, very rarely (ie: never), it's not a huge problem. But it's used for emergency broadcasts here, so it probably needs to work. I've organised to pick up a secondhand module for $25 in a few days, and I've ordered a Myldan 65mm short stubby aerial from eBay for $30 AUD to replace the factory whip, so that should cover it. Hopefully.

In the meantime, my airbag code reader tool arrived today, as well as a pair of new seat belt outlet trims for the convertible front seat belts. They'll go in in the next few days, and efforts into discovering why the airbag light on the dash is illuminated will begin. I feel it's something to do with the previous owner installing the E46 M3 front seats. I'm also still getting a brake light warning on the OBC - sounds like the common issues are the loom on the passenger side of the trunk lid (fraying or damage inside the sheath), or a worn brake pedal switch. Multimeter!!