Meter/reverse/regulator fuse keeps blowing

[Davidm]

Hey guys, 

I keep blowing a fuse and I can’t figure out why. Replaced the voltage regulator not too long ago and have checked all the wires but none are touching. 
Was wondering if maybe you guys could help me out. Was thinking it could be cause of some bad fusible links or maybe cause of driving in too low of an rpm. I was driving in traffic and it was a constant stop and go. But it blows at high rpms sometimes too. 

 

I drive a 1972 620

 

Thank you

David

[datzenmike]

 72.5 is 01 Jan '72 or half way through the '72 model year. The year starts the previous June usually. I know, weird. I have found some part numbers for May '72 and I seem to remember April as the earliest 620 made but regardless the part years are lumped in with the '73 model year. Always ask for '73 or you may end up the 521 parts.

 

There is only one fusible link so if it''ss bad nothing works.

 

So dash gauges stop working? reverse lights???? There is no fuse for the voltage regulator. 

 

Get a meter and measure the voltage across the battery when running and when revved up... should be 13.8 to 14.4v. If the new regulator is over charging that might blow fuses.

[Davidm]

Yea when that fuse blows all the lights stop working along with my gas and temperature  gauge. I’ll send you the link to the fuse block cover. 
the fuse on the bottom left keeps blowing. 
 

http://datsun1200.com/modules/mediawiki/index.php?title=Fuse_Box

 

[datzenmike]

Can't be all the lights. Be specific. Headlights and running/dash lights are on different fuses. Did you mean charge and oil lights in the dash go out?

[thisismatt]

If that page is accurate to the 620, that fuse is for the following:

 

[datzenmike]

Look at last thing changed as the cause of any new problem. Your battery is charged up so unplug the voltage regulator and drive it around on the charge in the battery. If the problem stops then it's the regulator. With headlights and heater off you can drive around all day on the battery, hopefully that won't be necessary.

 

Take the regulator back and get a new one. It's probably over charging. (not good for your battery) Think of voltage as pressure behind current flow. 18v is going to push 50% more current through any fuse than 12v and may blow it.

 

Over charging will slowly cook your battery. It may even boil over.

 

Borrow a volt meter and check.

[Davidm]

Yes sorry

The charge and oil lights go out. Everything in the dash goes out. My headlights still work but the green arrows don’t turn on. When the fuse isn’t blown my headlights go out when I push the turn signal forward to use my brights.

[Davidm]

Also when the fuse goes out I have to disconnect my battery otherwise it will die. Could that be an exposed wire?

[datzenmike]

 Headlights should not be affected by that fuse. The high beam filaments may be burned out. (again perhaps from an over charging regulator)

[Davidm]

Got it

That explains why I went through two batteries in a few months.

[thisismatt]

Anyone doing work on their own vehicles should at least have a cheap multimeter.  I was going to suggest a specific Craftsman model but ffs they are now ridiculously priced.

[banzai510(hainz)]

I had a bad alternator once on my 521 that would pop fusesnand pop the solid state volt regs I had