Electrical Mystery!!

[Dylanb23]

So its night time

 

I have my lights on and im about to turn.

First... I hit the brakes... ---> The brake lights go on in back.

But as the brake lights go on something in the circuit cuts out making the head lights go out for a second.

I hit the turning signal.. and it does the same thing. all lights will cut out when one relays.

I have a stereo set up and i have a feeling my buddy who put it in just hooked it up to the old cigarette lighter leeds.

When music is going on i sometime turns off it self. but will for sure do it when you do anything that has to do with lights.

Its hard to rock out when your song cuts out when you hit the brake...

 

 

Does any of this make sense?

Any ideas?

 

All the fuses are good.

And there was a time when it worked. with in the last month this has happened and confused me greatly

 

anything helps

 

Thanks

[Jayden71]

Stock Alternator??

 

My brother in law had this happen all the time. Too much draw for that lil 35 amp alt.

 

Thats my .02 cents

[ggzilla]

Your battery holds enough current even if the alternator stops working temporarily! 35A is enough to keep it charged with headlights, running light and everything.

 

This is a problem, not just a design issue. If you replace the 35A with 50A or 60A, and it solved it, so would have a new 35A.

 

Sounds to me like a loose connection somewhere, maybe a bad ground wire, or a bad relay.

[metalmonkey47]

Sounds to me like a loose connection somewhere, maybe a bad ground wire, or a bad relay.

 

X2

 

 

 

Also check for corrosion on terminals in the fuse box. I had a problem for some time where my turn signals and headlights wouldn't both work at the same time. Solved it by cleaning up some unseen corrosion on the fuse box.

[Dylanb23]

I was considering the alt, but I was thinking the same thing as jayden, it should hold up.

 

Is there a wiring diagram?

 

 

 

And i guess a side note..

Where could i find a new wiring harness.

A restoration is in the near future.

[Laecaon]

If I had the stereo up too loud at idle in my Thunderbird the car died. Did it even sooner with the headlights on. On my mercedes the headlights would dim on every bass note.

[elmerfudpucker]

Sounds like bad ground, could be the stereo or install.Cleanin the fuse box would be good idea as suggested,also clean the battery connections and grounds under the hood.

[Iowa Mark]

I'll pile on too! Battery or chassis ground. The new electrical draw is hunting for a place to complete the connection.

[defdes]

Douche the box.

[INDY510]

It sounds like your stereo is running off the same fuse or the same ground as your brake lights

 

 

 

Parking lights are the same fuse as dash lights.....

 

 

 

I would try dissconnecting the "Stop Lamp" fuse ........... then drive around and see if it still does it.....

 

 

 

Either way I would run a new in-line fuse to the red wire on your stereo.......... and the yellow wire is normally triggered by the ACC ignition switch............ which gets tricky when just picking a random wire to use for your stereo.......... I like having the stereo on a toggle switch (so NO datsun wiring is involved)

 

And run a NEW ground wire for the stereo........ there is no reason to use a 40 yr old ground wire

[datzenmike]

The battery will hold lots of extra power for times when the draw is more than the output of your alt. But if running a big amp you will exhaust this and the voltage at the battery will drop lower and lower. When it dips into the tens the transistors will crap out and the stereo will act up. If you are already at 11-12 volts while driving, simply applying the brakes will be enough draw to dip into the 10s and the stereo will crap. Even a depleted battery with only 10-11 volts will start and act normal.

 

You can clean and tighten all connections but in the long run you need a higher output alt. The early 620s are 28 amp I believe, barely enough for lights, heater and wipers. A 510 alt is 50 amp as is the 610/710. All Nissan alts after '78 are internally regulated. Late S10 (200sx) and S110 and A10s are 50 amp . The 720 trucks are 50/60 amp and I am running an '89 240sx alt with 80 amp output but mods are needed.

 

Also the 50 amp alts are much larger that the stock 620 alt and will hit the top of the idler arm grease nipple.

[ggzilla]

Early 510s have a 35A alternator.

Some 720s do too, they are internally regulated and I'll trade a 35A 720 alternator for a 50A one. I want the small one.

[datzenmike]

So they do! But only the '80. Did not know this. The only '80 720 I stripped had the larger 60 amp, so either it was swapped or a Canadian option for the colder weather. :lol: This would be the same one as on the 620.

[moparvwfreak]

sounds like a bad ground. i gotta go through my truck because of the same thing. i hit the turns and my lights will step out fo r a moment than back on.

[INDY510]

Also the 50 amp alts are much larger that the stock 620 alt and will hit the top of the idler arm grease nipple.

 

He has a 521.......... .. will a 510 alt work?.................. I've got one that probably works for free

 

 

 

And I'm local....... ;) ................ .... it's externally regulated,,,,,, but will the 521 regulator work?......... I might have the 510 regulator too....

[datzenmike]

It probably will. The regulator senses the voltage and mechanically adds more field current to increase output when there is a sudden load. Plus both alts are virch the same anyway.

[Dylanb23]

You guy are rad! thanks for all the help.

My truck has accumulated a hand full of problems in the last month. otherwise its a rock.

 

 

What would a 50a do compared to the 35a?

[datzenmike]

Well as long as your total in use load (head lights, heater, wipers, stereo) does not exceed the 50 amps output from the alt. you won't notice anything. Just remember, you can't take more out of the system than is in it. If it's a cold wet night and you have the heater/wiper/headlights on you may have to turn the stereo down.

[hang_510]

along with the grounds, check the wiring around the relays.

 

my 510 HL relay was hanging on with a total of 5 strands.

all electrical gremlin problems went away after i repaired it.

 

My truck has accumulated a hand full of problems in the last month. otherwise its a rock.

sounds like a chevy...

[Dylanb23]

along with the grounds, check the wiring around the relays.

 

my 510 HL relay was hanging on with a total of 5 strands.

all electrical gremlin problems went away after i repaired it.

 

 

 

 

I checked all of the relays.. they look clean. surprisingly clean.

I havent seen anything that is out of the ordinary.

 

I might have found some loose ones. ill post some pics up soon.

What doesnt make sense is that everything has worked before.

 

Is it possible that a 50a alt would help and/or fix it?

[ggzilla]

Anything is possible.

[datzenmike]

Is it possible that a 50a alt would help and/or fix it?

 

Asked and answered...

 

Well as long as your total in use load (head lights, heater, wipers, stereo) does not exceed the 50 amps output from the alt. you won't notice anything. Just remember, you can't take more out of the system than is in it. If it's a cold wet night and you have the heater/wiper/headlights on you may have to turn the stereo down.

 

The 35 amp on it should just barely run everything at once. A 50 amp alt. will improve the heater and wiper speeds at idle and the headlights won't dim when the turn signal is used. But if your stereo is drawing 50 amps you can see that you are going to have problems running everything at once. Admittedly, it's not often that everything is running at once so a 50 amp might be enough for you.

 

Try a search on here for a GM 90 alt swap. They are cheap and plentiful in the wrecking yards.

[hang_510]

I havent seen anything that is out of the ordinary.

 

I might have found some loose ones. ill post some pics up soon.

What doesnt make sense is that everything has worked before.

when you think its electrical, its fuel...

 

 

mine did as well, in fact i had just moved them around and then they started intermittantly acting up.

wasnt until i removed it and had in my hand that i discovered the wires...