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[Diamond Black Geezer]

You think life is chucking enough car jobs at you, so after swapping a rear door from the donor 'peanut' we find the rear speaker doesn't work!

OOps, ''this loom is a duff'n'' so we think. Only to realise that the other rear door doesn't work either. This door hasn't been changed.

The little 'base' speakers in the parcel shelf do work, as do the fronts. It's ye old SC804 8-speaker setup with autochanger. Not sure if there's the separate amp in the boot, might be.

Presumably my first port of call will be checking there's no power going to the speaker wires, but after that not really sure.  Oh, and please speak slowly and in idiot-speak I have said before car electrics and specifically audio I have no clue about! 

[zirk]

Some of the older CDX's had a additional Phillips Amp Installed in there, if that helps, so more connections to check.

[Diamond Black Geezer]

I shall have myself a little nosey. 

[Dave DND]

You would be amazed how many turn up here for a diagnostics with the BALANCE or FADER control wound to the wrong place

Just double check it to be sure   

[Diamond Black Geezer]

haha. I bet, actually Dave!

Yes, that's how we tested initially, wound the rear-only speakers, to get a soft hummmum-hummum from the parcel shelf, but to our utter astonishment, no sound from either rear door. I now am in that odd place of wondering if they ever worked. 

Not that it should make a massive issue, but he head unit is a replacement, after years of the FM not working, and various advice pointing to the amp, when a replacement head unit came up, I got it, and that cured the problem.

Is there an idiot-proof way of testing tracing the fault? (I now own a multimeter) And does the parcel shelf speaker working, while the rear door ones not (both main and tweeter) aid in the diagnostics? To my simple mind it 'feels' like the HU to me, but that's but a hunch, based on zero knowledge!  Appreciated Dave. 

[05omegav6]

If both rear speakers don't work, the the issue is more likely either with the amp (if fitted) or the headunit rather than the door looms/speakers

[Diamond Black Geezer]

yeah, sounds about right. I'll have a dig, see if fitted... offside inner arch, as well/instead of under the parcel shelf, yes? Are all Omega amps (minus bose of course) interchangeable?

If so getting a replacement shouldn't be an issue.

[Entwood]

Old tip, probably frowned on now ... 9 volt battery (pp9) with short leads attached to each terminal ... connect one to the speaker input then "tap" the other on the other input .. you "should" hear a small "donk" noise. You can use this method all the way back to the amp/head unit connections, if the "donk" occurs at the speaker, but not at the amp/headunit connections you have a break in the loom, step by step to find it. If the looms are OK then the amp/headunit is suspect .. its the same as using a multimeter but easier as you are listening not trying to read a meter..   

[Dave DND]

Old tip, probably frowned on now ...

Quite the reverse - in some cases we still resort to that one

Just make sure you only briefly "tap" the wires to get a "pop" as any more than a split second will damage the speakers   

[zirk]

Old tip, probably frowned on now ...

Quite the reverse - in some cases we still resort to that one

Just make sure you only briefly "tap" the wires to get a "pop" as any more than a split second will damage the speakers   

Or if your going a bit deaf, like me, use a 24V fully Charged Lorry Battery and some Jump Leads, not so much of a 'donk' or 'pop' more of a 'smoothing sizzling crackling' noise followed by a 'Bang', yea heard that. leave it on long enough and you can test how good the Amp and Speaker cables are were.   

[Diamond Black Geezer]

Well... the plot thickens!

Having my multimter on me today, I had a play about. Managed to find the 'beep' mode for testing wire continuity(?) and it beeped. Showed, on 2v mode 0.24v. I compared this with a front speaker, which read about the same, maybe 0.21 I think.

So... I plugged everything back in and wow! Music!

BOTH rear speakers working, so presumably they're on the same circuit, yes? I then pack everything up, and then realise the back ones have stopped working again!!! 

Next test? 

[Diamond Black Geezer]

PS Zirk... I may try that on my spare Omega, yeh? 

[Diamond Black Geezer]

UPDATE!

So, after a quick ponder, I thought 'what is the only thing that's changed? it's been literally a few mins from working, to suddenly not working again'...'is is an intermittent amp fault, maybe? gives up the ghost after a minute of running, then works again after a rest? What??'

'or.... wait a sec, I shut all the doors, as I packed up...'

So, I nipped outside again in my remaining 37seconds of dinnerhour, opened the back doors, and hey presto! Speakers work! Open and close the back door gently and there's a buzz and crackle from the speaker as it cuts out and splutters back into life.

So, that's Mr Stuffed Old Loom No 2! That's two in the last week, haha. I'll keep my old ones perhaps to maybe make a repair one day, as who knows, this new loom may conk out in weeks/months. 

[zirk]

Sounds to me like intermittent wiring around the door hinge, best case occasional open cct, or it the speaker cables are shorting to each other or vehicle chassis, so could case the Amp/HU stage to shut down or worst pack up al together, so needs sorting.

Did you work out wither it had an Amp in there, guessing there pretty rare these days, so if you do blow it up, will probably be new setup required.

[Diamond Black Geezer]

Yeah that door is getting swapped over in the near future, possibly this weekend, so definitely be looked at soon.

No idea how rare the amp is, yet. It's a standard setup, interchangeable speakers etc, so hoping amps wont be a pain to get hold of. Hoping