Park Tail fuse melting box?

[svwilbur]

Did you see how the fuse looks inside?
Why did it not blow?
It looks like it is melting too. As far as I know everything is still operational. I have not tested it all but I have not noticed anything not working while driving. Allthough I do not drive at night very often.

[svwilbur]

That is a nicer schematic. Does not match what is in the manual.

[Jdflyer]

Usually the fuse box melting is caused by the rivet getting loose and corrosion between the "Bus Bar" and the little spring clip the holds the fuse.
If the fuses are just getting warm, you can usually peen the rivet. You need to take a fuse box off and support the other side with something very solid. I put a punch in a vise as an anvil.

That would definitely do it. Regardless of where the short happened I would replace that fuse box. I would also connect the put an ammeter between the Red/Gray wire suppling power to that side of the fuse box and the Green/White wire leaving the fuse box. If that spikes above 20A's you know there are other problems.

[svwilbur]

Jdflyer you said:
"Once the light switch is turned on it connects pin 4 of the switch to pin three (G/W to G/B)
The G/B goes to the headlight relay and then the front parking lamps.
A R/B is spliced into the G/B not far after the switch going in two different directions. 1 to the rheostat and the other then becomes G/W again just before it passes into the rear harness where it goes to the rear parking lights."

Pin 3 says GL on the schematic I posted not G/B. I do not see the R/B splice either.

I'm using the schematic from the tech section: http://www.311s.org/PDFs/1969-70%20Dats ... 20rev9.pdf

That is a nicer schematic, in color and shows the hops and connections better. It does not match what is in the manual. And it makes sense with what you were saying. I can follow that R/B path now.

[svwilbur]

Usually the fuse box melting is caused by the rivet getting loose and corrosion between the "Bus Bar" and the little spring clip the holds the fuse.
If the fuses are just getting warm, you can usually peen the rivet. You need to take a fuse box off and support the other side with something very solid. I put a punch in a vise as an anvil.

That would definitely do it. Regardless of where the short happened I would replace that fuse box. I would also connect the put an ammeter between the Red/Gray wire suppling power to that side of the fuse box and the Green/White wire leaving the fuse box. If that spikes above 20A's you know there are other problems.

That makes sense. i think i will replace the fuse first. But then I have to power it on to take that ammeter reading. Just a little scared about smoking stuff. But presumably it is a slow melt. Check it with the lights off then progressively DO PARK AND THEN HEAD LIGHTS. And watch the ammeter. Surprised i never smelt it but then with the top down......

Maybe all the bumpy roads don't help.

[svwilbur]

JDflyer are you saying connect ammeter on either side of the fuse or somewhere else for the the Red/Gray wire?
Seems like it needs to be elsewhere. I don't usually check amps often so I am a bit rusty. Mostly do continuity and voltage.
Or do you do this with the fuse out? I think the ammeter has to be inline to get amps. SO I hook to both feed lines with the fuse removed. CORRECT?

Aren't most ammeters just 10A for DC. This needs more than that right? It is a 20 AMP fuse.

[spyder]

I was going home from work one night my tail lights fuse popped. I did not know that but Mr. officer attitude did. As he was writing the ticket, I had replaced the fuse. I said they work now so no need for the ticket. Turned out this was just before I replaced the alternator because original charging system was failing. So .... the car was running on the battery which was discharging while driving home and the current draw from bulbs went up as they dimmed, causing the fuse to pop. Check your battery voltage with the lights and engine on to see if the battery is around 13.5 volts, if lower check into your charging circuit.

[Jdflyer]

JDflyer are you saying connect ammeter on either side of the fuse or somewhere else for the the Red/Gray wire?
Seems like it needs to be elsewhere. I don't usually check amps often so I am a bit rusty. Mostly do continuity and voltage.
Or do you do this with the fuse out? I think the ammeter has to be inline to get amps. SO I hook to both feed lines with the fuse removed. CORRECT?

Aren't most ammeters just 10A for DC. This needs more than that right? It is a 20 AMP fuse.

Do not install a fuse!
Make sure your connections during the test are momentary. I.e. Turn lights switch on, then touch other contact with multimeter probe and take reading.
Need to be inline to measure amps.
Max reading will be dependent upon the multimeter.

[jrusso07]

STG switch is in the ignition and closes when key is inserted. Assuming buzzer and door switch are not disabled, when you open door with key in ignition, the buzzer sounds (don't leave key in ignition before you get out!).

Suspect fuse attempting to blow is due to heat, not due to short somewhere. Heat likely due to loose or corroded rivet as Phil suggest. Been there, done that.

I think fuse box cover is common to other Datsun models. My 510 had the same cover...think that is where the AC comes in to play.

I had a problem in my dimmer rheostat where the full on spot on the rheostat (read variable resistor) actually shorted it to ground and would cause the fuse to blow. The fact that your fuse isn't blowing likely means your circuit is ok. other indicators of bad circuit would be a dark, dim or bright light bulb as compared to others.

If you can't make measurements as suggested, you can chicken test with lower amp fuses. Start with an 8 amp or 10am and see if it blows. If not, suggest heat in rivot is the problem. Replace fuse box or wire in a in line type fuse for temporary fix.

[C.Costine]

Usually the fuse box melting is caused by the rivet getting loose and corrosion between the "Bus Bar" and the little spring clip the holds the fuse.
If the fuses are just getting warm, you can usually peen the rivet. You need to take a fuse box off and support the other side with something very solid. I put a punch in a vise as an anvil.

Over the years I have seen far more wires,terminal blocks, etc. melted from loose connections than from overloads. Many pieces of equipment needed to have all of the connections tightened up after installing because either they did not get them tight at the factory or they loosened during shipping.

[fj20spl311]

Over the years I have seen far more wires,terminal blocks, etc. melted from loose connections than from overloads. Many pieces of equipment needed to have all of the connections tightened up after installing because either they did not get them tight at the factory or they loosened during shipping.

THIS IS CORRECT. LOCALIZED MELTING IS NOT A OVERLOAD PROBLEM......Put away your amp meters, what you need is an OHM meter or your fingers....LOL

When the circuit energized, just touch the different connection spots. If its localized "warm" you have a bad connection. If it hot you have a very bad connection.

[Linda]

The only thing I consistently remember about electrical stuff is the importance of grounds and clean connections. So I always start by disconnecting the neg battery cable and using good electrical contact cleaner, like CRC, start spraying. Anything suspected gets cleaned but regardless it is a good starting point and easy. I'd take the fuse box out and clean it completely with spray or soaking in vinegar then rinsing. All grounds can be sanded, sprayed. . Don't attempt to pull any plug pins unless you have spare parts from vintage connections.com.
Linda

[redroadster]

It is a arcing connection electrons produce a 11,000 degree arc I use low temp solder to cover the connection and wire
It happens on jet liners too, on their mostly a/c 100 miles of wiring

[fj20spl311]

http://www.311s.org/PDFs/1969-70%20Dats ... 20rev9.pdf

If you use adobe reader, you can print it as a POSTER of 33" x 22" 16 sheets in total.
Just tape them together....lots of room to write notes on the printout.

If you do a lot, take the file to Kinko's have a laminated poster for the wall.

[svwilbur]

The only thing I consistently remember about electrical stuff is the importance of grounds and clean connections. So I always start by disconnecting the neg battery cable and using good electrical contact cleaner, start spraying. Anything suspected gets cleaned but regardless it is a good starting point and easy. I'd take the fuse box out and clean it completely with spray or soaking in vinegar then rinsing. All grounds can be sanded, sprayed. With this approach as a base then I can attempt to zero in.
Really just starting at the front of the car and spraying every socket, plug, ground, relay, battery cables etc is a nice preventative maintainence to do once a year at least and is pretty fast. Don't attempt to pull any plug pins unless you have spare parts from vintage connections.com, just a preliminary spray might help and not hurt anything.

Linda

what is a good electrical contact cleaner?
I have some spray-on Tuner Cleaner type stuff, will that work or do you have a better product?