Hello,
Just got a gift Pioneer X8700BT Radio (inst. manual - https://catalogs.pioneer-car.eu/Manuals/DEH_X8700BT_QRD3259_installation_manual/?page=2)
The manual advises "Do not connect the yellow cable(12V const) to the battery by passing it through the hole to the engine compartment"
The car is Renault 11 1985, the stock wiring only has switched 12V. How am I supposed to feed it 12V const so it doesnt lose it's memory every time the car is switched off?
That's under the "To prevent a short-circuit...." heading.
I think their concern is the wire insulation chafing and creating a short.
You have constant battery power going to your ignition switch. More than likely to your headlight switch also. Follow one of those wires down from one of those switches. They're both higher amperage wires. See if there's a good place to install a fused connection to that yellow wire on your radio wiring.
make a new circuit from the cabin fuse box
I think they meant to say that do not directly connect it to the battery terminal. You can use wires with inline fuse for this purpose.
Baloney. You need a 12v non-switched source to keep your time and settings. Page 3 of the instructions, item 4 says connect to a constant 12v source. If you can't find one inside the cab to tap into, go directly to the battery thru the firewall with a grommet to prevent a dead short.
Also, use an inline fuse.
Also, the hot wire to the lighter.