Which Fuse Has Constant Power in my '75?, Need To Connect Yellow "Memory" Wire on Stereo Options

[Rick986]

Guys - I have maxed out my electrical brainpower and can't find an answer specific to my '75. Can a kind sole out there please give me the answer?

Red power wire is switched, yellow needs to stay hot. Thanks in advance....

[GregAmy]

S11, which powers the emergency flashers, black/red wire.

There's also a battery hot wire on the ignition switch. Red wire.

Grab yee a VOM.

[Rick986]

S11, which powers the emergency flashers, black/red wire.

There's also a battery hot wire on the ignition switch. Red wire.

Grab yee a VOM.

Thanks Greg. Yup, need the VOM.

BTW, do you know what gauge wires are going into that fuse box? Many thanks!

[GregAmy]

S11 shows a red 4.0mm (~AWG6) going in, and a black/red 1.0mm (~AWG18) coming out. Red/Black also splices to a 0.5mm black going to the clock (if you have it), the seatbelt warning system...and red/black to the interior light.

The bigger red wire is one of the four Gang of Red that's attached directly to the battery. So if you tap it upstream of the fusebox (red wire) ensure to drop a fuse in it.

I never understood why VW/Porsche ran the Gang of Red without a fuse at the battery...<shrug>

Edit: BTW, these are all per the 1974 wiring diagram.

[FlacaProductions]

yeah - i was going to suggest a piggyback off of the clock connection right off the back of the clock. If you have one...

[Costa05]

S11 shows a red 4.0mm (~AWG6) going in, and a black/red 1.0mm (~AWG18) coming out. Red/Black also splices to a 0.5mm black going to the clock (if you have it), the seatbelt warning system...and red/black to the interior light.

The bigger red wire is one of the four Gang of Red that's attached directly to the battery. So if you tap it upstream of the fusebox (red wire) ensure to drop a fuse in it.

I never understood why VW/Porsche ran the Gang of Red without a fuse at the battery...<shrug>

Edit: BTW, these are all per the 1974 wiring diagram.

(IMG:style_emoticons/default/agree.gif) no fuses at all upstream at the battery is not good. I personally would run a new wire (circuit for your use) from battery and fuse it. Then go from there to whatever you are trying to power.

[GregAmy]

The Gang of Four supplies power to the entire car, EXCEPT the starter and alternator:

- Ignition switch, circuit 30
- S11 as described above
- S13 fuse (on relay plate), power to heater J14 blower relay
- J16 power supply relay

I'd suggest installing a resettable circuit breaker in a convenient place bisecting the wire from the battery to the Gang; 100A oughtta be enough to protect that circuit (4xAWG6 is roughly 200A total but I simply cannot imagine the whole normally-equipped car - minus starter and generator - draws more than 100A).

I've not seen a stock car - my two cars were already altered and batteries re-located - so I can't suggest where that location might be...I installed fuses/breakers in both.

https://www.amazon.com/gp/product/B06Y4ZQ5SC

That still leaves the big B-lead between battery and starter and alternator unfused, so, well, keep your fingers crossed.