Question about car audio electrical systems

Hi,

bin gerade dabei einen Verstärker einzubauen und habe festgestellt, dass der Strom bei "Ein" (ohne irdendwelche Anschlüsse) 0,6 Ampere beträgt->zu viel für Stillstand des Fahrzeugs. Nun gibt es die Möglichkeit den Verstärker über den zweiten Plusanschluss (Schalter) ein- und auszuschalten. Ich muss also den zweiten Anschluss für den Betrieb auf Plus schalten. Das Problem ist aber, dass die Leitungen zum Autoradio Dauerplus und Dauermasse führen. Beim Autoradio selbst gibt es auch keinen Plusausgang, der z.B. nur bei Radio ein Plus führt. Sehe ich es also richtig, dass ich irgendeine Leitung vom Zündschloss anzapfen muss, um den Verstärker bei Zündung aus, ausschalten zu können? Ist It's actually quite strange that there's no switched positive wire coming from the ignition switch. It's been moved to the radio (that's how it was with my old one).

VW Passat 1Z 1995.

Thank you in advance for the answers

Hi,
Then your Passat would be a significant exception. Please take the measuring device again and check the voltage at the radio. But remember that what used to be called 'ignition plus' (Klemme 15) is now, as far as I recall, called 'ACC' and only becomes de-energized after the key is removed from the ignition switch.
Best regards, Andy.

@andy

That's exactly how it is!

Hi,

Okay, I've got it: The second red cable (thin) provides 12V when the key is not fully turned to the ignition position. However, this cable does not provide 12V when the engine is being pre-glowed (and when the key is pulled out). It seems that the engine control unit deactivates this cable (or grounds it) during the pre-glow/start process to ensure maximum current flow for the starter motor, etc. Then, hopefully, it should also provide positive voltage when the engine is running (which is why I didn't want to start it specifically).

I've been trying to find this cable the whole time with the ignition "on" .

Hi,

Hmmm, either there's a bug in my code that's affecting every detail, or this is supposed to be like this.

The aforementioned power line does not carry any voltage when the ignition is on or the engine is running. I have to turn the ignition key back slightly (even with the engine running) for the line to carry 12 volts + and for my amplifier to work . The two remaining small cables definitely carry ground. Is this intentional on the part of the designer, or is my ignition switch or control unit malfunctioning ?

I would say something is wrong. Do you have an electric sunroof? It only works when the ignition is on...
Does your radio always stay on, even when you leave the car running? The radio in my Passat always turns off in that situation (all the radios I've tried have done the same; this is the third one I've installed).

DocSnydor wrote:

I would say there's something wrong. Do you have an electric sunroof?

It only works when the ignition is on...


Hi Docsnydor,

Let's see if I can discover anything about my Passi that works

DocSnydor wrote:

.... Okay, so I need to find a different power source (e.g., the sunroof). I need to check if a significant amount of current flows through the amplifier's switch contact (but I don't think so... probably 6 volts and a few milliamps would be enough to turn it on).

Does your radio always stay on, even when you leave the car running? My radio in my Passat always turns off in that situation (all the radios I've had have done that, this is the 3rd one I've had)}

"Mine stays on, but my battery is also brand new. In my old Passat, all the radios would also turn off due to the significant voltage drop (due to corroded contacts on the ground straps, etc.)."

hi christian,


To my knowledge, quite a few consumer devices should be switched off when turning the ignition key, so that enough power is available for the starting process. This also temporarily switches off the radio. However, in my opinion, this has nothing to do with corroded contacts or new batteries! I think it's implemented via the ignition switch. This was the case with my 1Z, anyway. It's possible that the problem in your case is actually related to the ignition switch.

joergs wrote:

also meines wissens nach sollten so ziemlich viele verbraucher beim drehen des zündschlüüsel abgeschaltet werden, damit genug strom für den anlaßvorgang zur verfügung steht. damit wird auch das radio kurzzeitg abgeschaltet. das hat aber meiner meinung nach nix mit korrodierten kontakten oder neuen batterien zu tun ! ist denke ich über das zündscloß realisiert ! bei meinem 1z war das jedenfalls so ! evtl. kann das bei dir wirklich am zündschloß liegen.

Hi Joerg,

Of course, I forgot to mention that I connected the Memory+ and the +Contact of the radio to a constant positive terminal -> therefore, it's independent of the ignition switch . I did the same thing in my old Passat and in our Audi. In this case, even with a weak battery, the radio might still turn off.

Okay, it's clear now! But I think the approach that VW is using is better. They switch off everything that's 'unnecessary and energy-consuming,' which maximizes the available power.

joergs wrote:

ok dann ist es klar !!!!! aber ich denke der weg, der da original von vw gegangen wird, der bessere. man schaltet alles "sinnlose und stromfressende" ab und hat damit maximale strom zur verfügung !

jaklar...if it would work for me . However, the car radio itself doesn't add much weight when starting the engine... you can easily compensate for that by pressing the clutch (then the starter motor has one less shaft to rotate)... with other consumers (e.g., lights), the effect is much more significant .

'But is the light being turned off, or is it just getting dimmer because of a failing battery? If I have time tonight, I'll check to see if there are different types of ignition switches, maybe that's the problem you're having! I vaguely remember that we had a problem with the radio once when we changed the ignition switch at my dad's place!'

joergs wrote:

aber das licht wird schon abgeschaltet oder wirds aufgrund zusammenbrechender batterie nur dunkler ? wenn ich zeit habe schau ich heute abend mal, ob es veilleicht unterschiedliche zündschlösser gibt, vielleicht ist es ja das problem bei dir ! ich kann mich dunkel daran erinnern, daß wir bei meinem dad mal ein problem mit dem radio hatten, als wir das zündschloß gewechselt hatten !

Hi Joerg,

Thank you in advance . As far as I know, the light will be switched off. This was the case with my old one, and it's probably the same with the new one: even when the magnetic switch is engaged, the light goes out -> there is no significant current flow.

Hello,

What kind of actions are you taking?
Many car radios (I've never had one without) offer an output that provides +12V when the radio is turned on. This can be used, for example, as a switching signal (attention, power handling capacity!) for a motorized antenna or an amplifier .
Please take another look at the pinout of the radio and list ALL pins and their meaning here!

Best regards, Rainer.

hello rainer,

If I understand Christians' concern correctly, he wants the amplifier to turn off when the ignition is off, and turn on when the ignition is on. Of course, most radios have such a connection! But that's not the solution to the problem, because the amplifier would be turned on when the radio is on (which also happens when the ignition is off), and he believes this would put too much strain on his battery.

Rainer K. wrote:

Many car radios (I've never had one without) offer an output that provides +12V when the radio is turned on. For example, this can be used as a switching signal (attention, power handling capacity!) for a motorized antenna or an amplifier . Guck Dir doch nochmal die Pinbelegung des Radios an und nenne hier ALLE Pins und ihre Bedeutung !

Hi Rainer,

You are right: the "Power Antenna" connector provides 12V+ -> meaning I can use this connector to turn my amplifier on and off synchronously with the radio . It's still strange that the switched 12V from the ignition switch is causing problems, but this is probably the best solution: the amplifier only runs when the radio is on (so it will work with my Aldi radio; my old Blaupunkt had an extra output for amplifiers).
@Jörg:

Don't stress about finding the problem with the 12+ ignition switch cable. There must be a loose connection somewhere; I can't imagine it being anything else.

What would I be without the kind cooperation of the forum members: