Headunit memory settings / cutting out

[owlsowls]

Apologies initially, as this is an E28 question, although I’m hoping most of the wiring is common...

I’ve recently treated the E28 to a new Pioneer headunit.

At first the unit would not power up at all, so I did the classic fix and switched the red and yellow perm./ignition wires over (something which my previous Phillips headunit did not need) – and the head unit powered up.

I set everything as I wanted it, in terms of stations etc., and paired my phone, everything seemed to work fine. I power cycled it a few times and the headunit was happy and remembered my settings.

I came to the car this morning, and all the settings had completely reset, as if I’d not set anything up, but oddly, had still remembered the Bluetooth link with my phone, which started playing immediately. I’m not sure what to think on this… My only thoughts are that the red and yellow wires were correct initially, just not secure, and I've caused the fault by swapping them over. Something I'll check this evening.


A separate issue, is that above ~70 volume, or on a particularly bass heavy track, the speakers cut out. In some situations, the headunit switches off completely. I’ve had a couple of thoughts; the speakers are still OEM, I’m not sure whether they’re 4ohm but I assume the headunit is expecting them to be. The new headunit is 50w-rms per channel, whereas the old one was 40, I don’t know whether that’s putting more strain on the electrical system which the car can’t handle, or maybe the alternator / cabling needs upgrading. I’ve already read about a factory amp between the headunit and the speakers which can cause all sorts of issue. Again, I'm struggling to diagnose the issue.

If anyone can shed any light on this it would be greatly appreciated.

[Contours]

Should be easy enough to check if you have connected the permanent live from the radio to a permanent live circuit with a multimeter or test light and see if you have power in the circuit with the ignition off. This circuit is also fused separately in the e30. I would say that the built in amp in your radio would not make much difference or cause a problem. If your speaker wires are touching the body occasionally, then the internal amp in the radio will self protect and cut sound to the speakers. There is also an unloader relay on the e30 where if your alternator is struggling, it will cut off power to non-essentials like the radio, heater etc, in order to keep the car running so you may want to check your alternator with a voltmeter.

[BenHar]

There is also an unloader relay on the e30 where if your alternator is struggling, it will cut off power to non-essentials like the radio, heater etc, in order to keep the car running so you may want to check your alternator with a voltmeter.

Are you sure about this? The unloader relay that I know of just shuts those things off when you activate the starter.

Ben

[Contours]

I had an alternator failure recently and the first thing to shut off was the stereo. I noticed that the items that shut off when starting the car are similar to when the alternator fails. Power was cut from unnecessary loads to maintain lights, fuel pump and essentials to keep the car moving. I dont know how the Ecu is set up to manage this situation but in any event I got the car home which was about 15 miles at night.

[Brianmoooore]

The unloader relays are controlled completely and exclusively by the starter motor solenoid, and are activated every time, and only when, the ignition switch is turned to its last position. They are normally open relays, so if the car's electrical voltage dropped low enough, they would drop out, but at that level, very little else would work on the car.
Are there still any radios made that rely on a permanent power source to retain settings? NVM (non volatile memory) chips were introduced into consumer electronics in the last half of the '80s. Prior to this, a small rechargeable battery (as in the SI instrument cluster memory) were used to retain settings, but not used in car radios, since there was a permanent 12 volt available.

[Contours]

Don't all radios have a permanent memory connector wire to retain radio station settings and the clock if included? All recent radios that I have fitted have one.

[owlsowls]

Firstly, thanks all for the replies.

From what I’ve read the unloader relays cut power to the wipers, fans, windows etc. to allow for enough power for the starter, and are driven from the starter itself. I don’t think the headunit forms part of that circuit and remains on when the car is started, but I could be wrong… If the headunit is part of the unloader system then a relay could be faulty (and I suspect the relays are the original components from the 80s). But, that does not explain the cut-out during peak power, which happens both when the car is running, and when it’s not. Nor does it explain why my previous headunit worked fine.

I believe the Pioneer unit relies on a permanent, low amp, 12v feed, as did the previous Phillips headunit. As Contours said, radios use this permanent feed to retain various settings. I have no idea why NVMs or flash type memory chips are not used, but I assume because they’d require re-flashing or similar each time a setting had been changed.

I’ll check the alternator, and, as I will also check the 12v feeds (like I said I would on the 18th…). If I’m still struggling, I’ll locate the unloader relays and stick them on a tester.

Thanks again all.

[Contours]

My radio shut off as my alternator failed and I think it has to do with the head unit not getting 12 volts and shutting down as a result. So, nothing to do with unloading as such I now believe having heard the views here. Perhaps, if you have a poweful amp, your alternator may be struggling to keep up and if system voltage dips below the 12 volts your radio may automatically switch off to protect its circuitry which is a more likely scenario.

[owlsowls]

My radio shut off as my alternator failed and I think it has to do with the head unit not getting 12 volts and shutting down as a result. So, nothing to do with unloading as such I now believe having heard the views here. Perhaps, if you have a poweful amp, your alternator may be struggling to keep up and if system voltage dips below the 12 volts your radio may automatically switch off to protect its circuitry which is a more likely scenario.

Yeah. This sounds most plausible for the cutting out above 70% volume or over peak watts. I think I’ll upgrade the alternator and the associated cabling at some point in the future to mitigate this. But this doesn’t explain the non-remembering.

[Contours]

Radio memory is on the circuit fused by no 21 in the fusebox which gives a permanent live to that along with your dash clock and interior lighting. You may have a wonky connection here or else you have not connected your radio memory to this circuit. If you look at the C302 accessory socket behind the glovebox the pin at V is for radio memory. I have my stereo set up incl. electric aerial and sub entirely connected to this C302 and the whole system works as it should. You can see a diagram of this C302 connector socket which is behind your glovebox on the net and which describes what the individual pin connectors are for. On my own car I discovered that an installer had previously and for handiness it seems connected the permanent live memory wire to the hazard switch which also has a permanent live feed. While not recommended it actually never caused a problem.

[BenHar]

https://www.e30zone.net/e30wiki/index.p ... ory_Socket

note that the diagram is upside down compared to the view in the car.

Ben

[owlsowls]

Thanks both for the informative response. I'll have a look at C302, although I've got an E28 rather than an E30 I assume the setup will be very similar.

It's interesting that it forms the same circuit as the dash clocks and interior lighting. I'm having a separate issue with intermittent function of the hazard light button / circuit, dash clocks, and dash clock illumination.

[owlsowls]

I’ve managed to resolve this issue. I swapped the red and yellow connections back to how they were originally configured for the previous headunit, and this time, the headunit powered up. I can only assume I’d not made the connections properly, or one of the cores was shorting out on the chassis or something. The headunit is now retaining all of its memory settings, and the cutting out issue has also been resolved... Feels like I solved it by coincidence...

Thanks all for your help, on to the next fault.