Truck drains battery

[Boom death]

So I'm having an issue with my 79 620 it seems to Drain the batteries in about a week I don't drive this truck as much as I should it sits in my garage for weeks and gets taken out on the weekends ... I've checked the voltage coming from the alternator it's about 13.8 volts so I know it is charging and yes I've replaced the battery twice and still having issues? Any help would be appreciated thanks

[Draker]

[Draker]

I didn't watch this video, but it should show you what you need to do.

[Dawa]

have any of the previous owners performed any 'electric work' that you

are aware of? (most likely they have.) trace the visible wires that you can

throughout the cabin (specifically around the stereo if it is aftermarket,) as

well as within the engine bay. you probably have a ground from bare wire/metal

contact/etc

[Boom death]

So no aftermarket radio or speakers it has original radio which still works am only ... I tried the above video and found out I have a 10am leak somewhere I also found that whenever I disconnect the negative side of the battery and plug it back in the little alarm under the dash goes off as if the key was placed in the ignition but it's not so I'm thinking it might be a ignition relay somewhere that is messed up

[Draker]

Start pulling fuses until you see that draw drop.. When it drops then you know what circuit to look at when troubleshooting.

[Boom death]

so i checked it these were my results .43amps or 430 milliamperes the video above said i should have no more than 50 miliamperes so i started to pull fuses out one at a time found out it was my upper left one a 20amp fuse is is the cause of my parasitic amperage draw i dont have the cover for my fuse box so i have no clue what it could be ?? did some searching and found a couple of different layouts some show a 20amp fuse for headlights the other a 10 amp fuse for solenoid ... does anyone have a fuse layout for a 79 datsun 620 kc?

[Boom death]

thanks draker u rock for the quick response it definately has helped me narrow down my problem :thumbup:  :thumbup:

[Draker]

No problem! I don't know the fuse diagram though.. hope someone else can come up with that piece of the puzzle.

[datsunaholic]

According to the 79 manual it's a 10A fuse for engine control, and should ONLY have power when the ignition is on.  But if the fuse box got replaced with an earlier one, that fuse was the hazard/stoplight fuse and was connected directly to the battery.  So, if the wrong fuse box was used, it'd be turning on all the engine control relays/switches ALL the time.  The wiring connectors LOOK the same year to year, but the wiring positions changed. 

 

Of course, easy way to tell- pull the fuse and see what DOESN'T work anymore.

 

Also, pull the other 3 fuses on the left side, since they are all supposed to be IGN controlled as well. 

 

Put the voltmeter on the fuses.  All 3 left-side fuses should have zero volts on them with the ignition off.  The 3 right side ones should have voltage all the time.  This ONLY applies to '75-79 trucks.

[Boom death]

Thanks guys for all the info found out it was the wrong fuse box in the truck went to the junk yard found a 79 620 and pulled the whole fuse box and a couple of relays and compared it they were way different now the alarm under the dash only turns on when the key is in the ignition on position ... Did my test for parasitic amperage draw and they were none.... Thanks again guys for all ur help

[datsunaholic]

That wrong fusebox is pretty desirable for someone with a 72-74 620.  It's rare to see one in good shape, many are melted.

[Boom death]

I got one if anyone need one