Hey guys

Was installing the head unit and speakers in Bob's s12 last night and the physical installation went great, sounds awesome, but then lost the headlight motors, rear lights, fuses blew etc. (Bob was doing the wiring, I have no clue on electrical stuff).

Anyhow, based on previous experience I understand this is a common occurrence when installing stereos in older cars, (even though nobody has posted on this site about it...) anybody have an idea what went wrong?

Well, it does depend on where the power supply for the Sound System was sourced as to what actually got overloaded.

My advice, to anyone who listens and thousands who don't, is to NEVER connect a high current accessory to existing wiring.

It will compromise other systems too much and at worst, cause a fire

The remedy is simple.
Add a new distribution cable from the -ve battery terminal to a new additional fuse distribution block.
Protect this new cable with a Maxi-Fuse, right at the battery post.
Then you can feed power to your new bits from either the new main cable or via new fuses mentioned above.
It doesn't matter whether you retain the original alternator or fit a high output one.
The wiring needs to be separate, dimensioned correctly for the designed load and protected correctly to prevent what you have experienced.
Here is a Wiring Diagram I drew up for a similar question on another forum.
It includes relays to minimise voltage drop and switch power when ignition is switched ON for example.

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Regards, Graeme
Just trying to help...
http://nissanman.shutterfly.com/
graemes@internode.on.net

I found a wiring diagram for the S12 and I found my mistake. When installing I used the loom that was running to the old radio. Poked around and found a ground, a full time +ve, and a switched +ve. Problem was that the ground was not really a ground, instead shoots off to the 'illumination control relay', the radio must have been one of the old school designs that grounds through the case. So it wasn't that I was overloading a fuse, it was that I was pulling up a ground that shouldnt have been pulled up.

So basically I ignored the advice that everyone gives and in fact I have given to others about running power for stereos, and I got bit. A rewire is pending, as is a smack on the back of the hands.

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$2000 challenge bluebird - no more.
RPS12 - 80s-o-rama. Currently dropping 200cc, gaining a cam and gaining a turbo.