Electrical Help

[BaKed]

hey guys i just recently have had some problems with the electrical in my 79 Datsun 620 King Cab.....to start my battery will not hold a charge but after i jump the car it runs ok....so first i thought it was the alternator and come to find out if my truck is running with a dead battery my alternator is doing something right.....now the second problem i am having is right next to my battery is a little black box with 2 gold relays(i think).....wehn i have the engine running they are making a BUZZING sound....its almost sounds like a really faint horn.....idk what is going on and figured i would resort to this site for some guidance.....BaKed

[banzai510(hainz)]

have you put a VOLT METER to it to get some volt readings first.

 

Battery could be shot cause the alternator wasnt charging it anymore or runs good during the day and at night is using more current cause of you using the lights ect.....

Give us more info.

 

 

Blk box???????Is that the volt regulator??????

 

 

maybe no water in battery?

[Skib]

pics of the black box?

[datzenmike]

That's likely the auto choke heater relay. It requires battery and alternator output in order to provide power to the auto choke. Get a cheap multi meter and check a few things.

[hvyd]

i have this same buzzing in my 79 620 kc. my buzzing seems to be coming from under dash. think its a bad relay but dont know for sure. has new battery and new saturn alternator.

[Cuts metal like mad]

Id guess your alternator is putting out enough power to run the truck but not enough to charge the battery. Or youj have a loose or bad ground on the battery. Both situations COULD cause the relays to act a littled wacky.

[hvyd]

when running with every light on alternator is still putting out 13.5 to 14 v to battery. on my truck under dash there is a black box about 1.5 in by 2.5 in mounted just above right kick panel i believe this is the culprit. the other thing is the switched wire to alternator stays hot with key off. idk. have to do some investigation.

[banzai510(hainz)]

the red/wht is usaully HOT all the time as it goes to the battery. fusable link ect.....

 

if it is swithced I would suspect maybe the volt reg but if a newer rig it will have a internal VR built in.

[hvyd]

i figured it out. its amazing what starts to work when you change some fuses. the buzzing turns out was the seatbelt warning buzzer. my dome light started working buzzer now goes off and cig lighter now works!!!!

[rAudiOne]

Thanks for all the tidbits in this thread. Was going nuts trying to figure out why cig quit working suddenly and all the fuses in the block were fine.