Electrical Problems, Please Help

The tail lights, turn signals, interior lights and gagues don't work.

The headlights, stereo, and engine do work.

I've replaced a couple bulbs to no avail, and the fuses appear fine.

The wires appear to be connected, but there is a small electric component box inside the car that I don't know much about.

Any diagnostic help would be great.

is this a new problem?
did it start after you did . . . . to the car?
or was it like that when you bought the car?

when you say gauges don't work, what gauges are you refering to?

we are still talking about a 68-74 datsun 510, right?

sounds like the wiring harness was cut or damaged. can't be sure from your description.

what condition is your interior in?
can you pull up your carpet and look at the section of harness that runs through the passenger compartment?
if so, is it in good shape? has it been pinched, cut, or otherwise damaged?

if the section of the harness between the dash and the back of the car is in good shape, the next place to look would be the dash harness.
if you are a big guy this might not be possible, but get a flashlight and take a look at the wires that run underneath the dash. do they look OK?

check your harness and post back, we'll take it from there. if your interior is really nice and you are worried that you will ruin it, you don't have to pull it apart, just know that a cut rear harness will cause the problems that you are describing.

Thanx DimeFury for your prompt response.

Yes, I am talking about my 70' 510 Coupe.

I knew it had these problems when I bought it, but I bought it because they're so rare, and the engine, suspension, transmission, body, exhaust are flawless, not to mention 510's are one of the raddest cars ever.

So I knew I'd have this electrical problem and would want to do some cosmetic things.

By gauges, I mean speedometer, tachometer, fuel, and oil.

I have no probmes messing with the interior, since I plan to replace/restore it all anyway.

A buddy of mine who used to rewire ski-lifts is coming over, and from what I described, he thinks it's a shady stereo install that may have caused the problems.

As far as the wire harness, where exactly does it come through?

Thank you so much for your help, I am admittedly new at the 'gearhead' mentality, but want to learn as much as I can so I can have my 510 for as long as possible.

no problem, hopefully i can help too.

i asked if it came that way to get more info on the situation, you don't have to defend buying a 510 with a few problems. they are hard to find at all, let alone in perfect condition.

if the harness between the dash and the back of the car has been damaged that would cause the gas gauge not to work. (or bad sender or wire not hooked up to sender)
the speedometer in these cars is mechanical and is driven by a cable. if your speedo doesn't work the cable isn't hooked up, is broken, or is missing completley.
it is rare for them to come stock with tachs and there is no stock oil gauge (had a warning light), these may be aftermarket gauges and may also not be hooked up properly. (you never know what the previous owner has done)

wiring harness routing (us version)
the stock wiring harness comes through the firewall on the passenger (right) side and runs underneath the dash to the drivers (left) side. it then runs down the firewall (behind and to the right of the pedals) and onto the drivers side floor pan. it runs right up against the trans tunnel and the wires for the interior "dome" light branch off where the front of the drivers seat mounts and run up the B pillar to the roof. the rest of the rear harness runs along the trans tunnel until it reaches where the front of the stock rear seat would go, then it turns toward the passenger side. it runs out into the trunk. it runs around the trunk on the pass side until it ends at the taillights.
(damn it is hard to try and describe a wiring harness/diagram)

i'm happy to help out a fellow 510 guy, hope that helps some.

post up some pics of the car if you get a chance.