Whenever i turn my dash and parking lights on, if I leave it for about 15 seconds, the fuse will blow.

What I have done so far that has not worked:

Disconnected all of the lights on the exterior of the car one at a time.

Swapped out the dimmer switch. 

Unplugged the cigarette lighter/under dash light.

Unplugged the glove box light.

Unplugged the clock, fuel and oil gauge lights.

Took apart the combo switch, cleaned/sanded the contact points.

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I have not been able to unplug the speedometer light or the tach light.

I found out that if i unplug the dimmer switch, or turn the dimmer switch all the way down to off, the fuse does not blow.

When the dash lights are on the green and white wire gets(at the switch) Extremely hot within seconds and appears to have done some damage to the plug. (Can this be replaced?)

It also seems that the green wire with a blue strip right next to it begins to get hot quickly, could they perhaps be arcing because of damage to the connector/plug and causing this problem?

I put some electrical tape around the Green/White wire because it looked like over heating may have created a small hole near the plug... this obviously did not fix the problem

Is there a way that I can eliminate the combo switch or confirm that it is the problem by jumping without the combo switch hooked up?

(I think there is a chance it is the combo switch as it was replaced after and electrical issue at the headlights)

 

 

You should contact Dave Erwin here, http://datsun-240z-upgrades.net/products/

He may reply to this thread but he's a busy guy.  I've read where people have sent their combo switch to him for refurbishing.

I believe you have a short somewhere! If it was mine I would unplug all the exterior lights and anything else I could get off the circuit. See if the fuse will hold then. Add one thing back at a time until you figure out where the short is. You could also change some of the exterior bulbs to LED. This circuit has a lot of load compared to the wire gauge Dave Irwins parking light relays will help once you find the problem

1 hour ago, Patcon said:

I believe you have a short somewhere! If it was mine I would unplug all the exterior lights and anything else I could get off the circuit. See if the fuse will hold then. Add one thing back at a time until you figure out where the short is. You could also change some of the exterior bulbs to LED. This circuit has a lot of load compared to the wire gauge Dave Irwins parking light relays will help once you find the problem

Maybe I just dont know what I am talking about here, as electrical is not really my thing. But I am pretty sure it has nothing to do with the parking lights because if I unplug the dash lights there is no issue and the parking lights dont pop the fuse.

Sounds like it's something to do with the bulbs that are dimmed with the knob.

One of the dash illumination bulbs shorted inside? One of the sockets shorted inside? Wiring fault? Pinched green/white somewhere to ground?

What year are we talking here?

1974 260z.

I have unplugged the dimmer and the fuse does not blow, I can also turn it all the way down to off, and it does not blow, but i have unplugged everything except for the speed/tac and it will still blow. Which makes me believe it is either something with the switch or the speed/tach. I would really like to eliminate the combo switch before I take the whole dash out if that is possible

39 minutes ago, surfsnake2 said:

I have unplugged the dimmer and the fuse does not blow, I can also turn it all the way down to off, and it does not blow

I missed that earlier...

You could figure out the connections to jump at the combo switch plug and just bypass the combo switch with jumper wires. that would isolate the combo switch...

Am I missing something here?  The dimmer is the obvious problem to me.  You unhook it or dial the power down and the fuse doesn't blow.

It's grounded above the cig lighter I think.  You should be able to see it from the floorboard, looking up.  Maybe it's loose.

45 minutes ago, siteunseen said:

Am I missing something here?  The dimmer is the obvious problem to me.  You unhook it or dial the power down and the fuse doesn't blow.

If i lower the power it will still eventually blow, just takes longer. Yes if i turn it off or unplug it it will not blow, However everything past it shuts off so I guess i was thinking that it could still be in the dash lights.

I will pull out the dimmer, if i remember correctly it just plugs into a connector up above.

You say there is a wire from the dimmer to somewhere above/around the cig lighter or does it run from the wires that plug into the connector for the dimmer?

I did a quick google search of 280z dash light blows fuse.  Here's the thread that mentions the inspection light in the engine bay also corroded side marker light sockets.

http://www.classiczcars.com/forums/topic/48516-keep-blowing-the-fuse-for-the-dash-lightstail-lightspark-lights-please-help/

And a connection above the fuse panel.