intermittent short

[Dolomite]

About a month ago my 510 started occasionally blowing the flasher fuse. The ammeter would start going crazy and end up showing 30+ amp discharge and pop the fuse. The odd thing is I could put a new fuse in and it would be fine for sometimes a block, sometimes a few days worth of driving. I started disconnecting things in the circuit to see if they were the problem. After removing the wire for the fuel sender, it didn't blow for close to a month. Today on my out to datsunville it blew 3 times with seemingly no obvious culprit. On my way home the gauge pegged 30 amps discharge but this time when I went to put a new fuse in, it sparked and immediately blew, I just hauled associated home so it wouldn't die on me because when the flasher fuse blows it quits charging. At home I put in a new fuse and it didn't blow, I took it for a couple miles and it didn't blow but I noticed the right turn signal indicator on the dash glowed faintly. I'm shitty with electrical...any ideas, suggestions?

[Dolomite]

Forgot to add the hazards work fine, even when the signal fuse blows.

[Lockleaf]

The wiring diagram I have for 71 shows the following things all run from that same fuse.

 

Hazards

Dome light

Engine bay light

Clock

Cigarette lighter

And some kind of elecrical associated with the steering lock?

 

Which of those have you disconnected?

[Draker]

Also turn signal switch, dash turn indiacators, and external lights.

[Dolomite]

I never thought about the dome light. That circuit also runs all the power to the dash lights, gauges, and highbeams. I've tried the turn signals, dash lights, and gauges. Maybe I'll try, flasher next and then dome light. Now I think of it, I think I remember boatman saying something about the door switches for the dome light. It doesn't work so maybe I'll just delete it. My car doesn't have a cig lighter, engine light, or clock so those are out.

[Draker]

The wires are still there for all of those accessories. If not terminated correctly in the back, they could be causing your issue.

[datsunaholic]

I know on my truck the flasher fuse would randomly blow out because the reverse light wiring had rubbed bare under the vehicle, and would short out on bumps and such.  Reverse and turn signals usually share a fuse.

[Dolomite]

I'll definitely check that, thanks. Probably going to get a cheap short finder too.

[banzai510(hainz)]

maybe replace the flasher Cans. or reseat the flasher Can as maybe a corrosion issue

 

 

clean fuse connection or reseat the plug to the fuse box

[D52E]

I had a similar issue

I know on my truck the flasher fuse would randomly blow out because the reverse light wiring had rubbed bare under the vehicle, and would short out on bumps and such.  Reverse and turn signals usually share a fuse.

I second this, my switch on the side of my dogleg trans would intermittently short on the trans tunnel.

[datzenmike]

Door switches only ground to turn the dome light on. If wire rubs bare the dome light comes on, not blow the fuse.  

[Dolomite]

Today I undid everything I fixed in the electrical system 6 months ago. I resoaked the fuse box and connectors in vinegar over night. Pulled the jumper wires that fixed the broken pathways on the instrument board thus disabling the idiot lights, fuel/temp gauge, dash lights. Returned the side markers to being just side markers, I had done the side marker turn signal upgrade. So now it's as I got it 15 years ago with the exception of turn signals working. I started it up and it barely registers a discharge as the signals flash at idle, it used to show a much larger discharge. Headlights on at idle is nearly no discharge, so far a huge improvement. At a couple thousand rpm, there's around 2-5 amp charge. Tomorrow I'm going for a decent drive to see if anything happens. If not, I'll add one circuit back at a time till it acts up again.

[datzenmike]

I think that is the best way.

[Dolomite]

I drove it three times today, so far so good.