Need Help here

[Montzzz]

i have a 1971 datsun 521 I notice that my brake lights were staying on all the time. The problem was at the brake pedal switch, it became loose so i unplugged one terminal and tight the switch. when i connect†ed back the terminal I accidentally touch the other terminal and I could see a tiny spark. After that my truck wouldnt start. Since is stickshift, i pushed it and started on second gear. Drove it for 20 minutes, ran fine then turned it back off and turn it back on and nothing, no juice whatsoever so ipushed it againg and started like that. While driving home i turn on the lights and the truck lost power, turned lights off and gain power. Got home and while the truck was on i took the negative terminal off the battery and truck died.
So my question is what did I burned? I check the fuses and they are all good.
thanx in advance

[flatcat19]

Are you any good with wiring? 

There should be a 521 wiring diagram pinned here somewhere. 

 

I assume you still have the glass fuses? 

I have never trusted glass fuses. Replace each fuse with the correct, corresponding fuse and go from there. 

 

Do you know that you have a good battery? Good alternator? Do you have an inline fusible link from the battery to the fuse block? Is that good?

Edited May 1 by flatcat19

[datzenmike]

That shouldn't do anything as you are only doing what the switch does when you step on the brakes. Send power to the rear lights to turn them on. If you touched it to ground the fuse would blow.

 

Clean your battery terminals and cable clamps. See if this helps and we'll go from there.

 

[Montzzz]

1 hour ago, flatcat19 said:

Are you any good with wiring? 

There should be a 521 wiring diagram pinned here somewhere. 

 

I assume you still have the glass fuses? 

I have never trusted glass fuses. Replace each fuse with the correct, corresponding fuse and go from there. 

 

Do you know that you have a good battery? Good alternator? Do you have an inline fusible link from the battery to the fuse block? Is that good?

electrical is something i dont really know. I still have glass fuses, i have a good battery, dont know if my alternator is good. How you test it?

 

[Montzzz]

1 hour ago, datzenmike said:

That shouldn't do anything as you are only doing what the switch does when you step on the brakes. Send power to the rear lights to turn them on. If you touched it to ground the fuse would blow.

 

Clean your battery terminals and cable clamps. See if this helps and we'll go from there.

 

Cleaned them, still doing the same

 

[datzenmike]

Clean the screw contacts on the fuse box. There are 4 that are tied together on the side with the Black (from battery), White (to ignition switch) and Red/Green (to headlights) All 15 amp fuses. Probably corroded.

 

As described this should not be happening. Your ignition switch is allowing the ignition to work but not the starter. This would not happen from the tail light switch being properly connected to the switch. There is a power wire from the battery to the fuse box, the ignition and the headlights. Turning the headlights on would draw a lot of power possibly dropping the power (voltage) to the ignition and why the ignition quits when they are turned on. It shouldn't. Do you have a test lamp or volt meter?   

 

Try pulling the small Black/Yellow wire off the starter solenoid and make sure it's got good contact.

[Rustbin]

If it died when you disconnected the battery it's the alternator. I had a similar situation on my first car, a 73 610. I took the alternator to my fathers friend who took it apart and he showed me how to test the continuity, bearings, brushes and the diode plate. I had fried some diodes and the brushes were worn out, the new diode plate and brushes cost me $25 in the '80's but that's all there is to them. For all the other electrical gremlins heed Datzenmikes advice.

[Montzzz]

On 5/1/2024 at 6:31 AM, datzenmike said:

Clean the screw contacts on the fuse box. There are 4 that are tied together on the side with the Black (from battery), White (to ignition switch) and Red/Green (to headlights) All 15 amp fuses. Probably corroded.

 

As described this should not be happening. Your ignition switch is allowing the ignition to work but not the starter. This would not happen from the tail light switch being properly connected to the switch. There is a power wire from the battery to the fuse box, the ignition and the headlights. Turning the headlights on would draw a lot of power possibly dropping the power (voltage) to the ignition and why the ignition quits when they are turned on. It shouldn't. Do you have a test lamp or volt meter?   

 

Try pulling the small Black/Yellow wire off the starter solenoid and make sure it's got good contact.

I do have a volt meter, got a new altenator, start the vehilce, plug the meter and voltage drops number by number

 

[datzenmike]

New.... is no guarantee that something works. In fact it something is just replaced without proof that it needs replacing, you just might put a bad one in, increasing the confusion.

[fiveoneO]

Sounds like your alternator isn't charging. Is it internally regulated or externally regulated? You should be able to take the alternator to any parts store and get it tested. Start ruling things out one by one. Eventually you'll find your problem. 

[Stoffregen Motorsports]

Do 521s have fusible links?

Edited May 4 by Stoffregen Motorsports

[datzenmike]

That's a good question. I assume so, just like the 510 it's on the power lead to the fuse box. Unlike the 510, which is wired to the starter lug, diagrammatically it's shown as a power wire from the battery post.

[henry]

1971 Datsun 510 SW 1.6L

 

         I'm more or less having the issue with alternator. Somehow I fried the fusible link wire from the starter lug.

     If I wanted to replace the fusible link with an in-line fuse what amperage should the fuse be?  I'm thinking that would be

    alright to do??  Thank you   Henry

[datzenmike]

Yes you could do that. What color was the original fusible link wire? From this we can get the current rating.

[Stoffregen Motorsports]

I use a circuit breaker instead of a fuse. Fuses pop in an instant while fusible links take some heat before they fry, so replacing it with a fuse gives you no wiggle room. Circuit breakers pop, but can be reset, or will reset by themselves.

 

[datzenmike]

Myself I would replace the link rather than a fuse. If you go with a fuse keep plenty of spares.

 

What color was the wire???

[henry]

Red.  thanks

[datzenmike]

 

50 amp then.

[banzai510(hainz)]

521s are nototrious for fuse issues.

I CLEAN ALL THE FUSE CONTACKS AND WIGGLE THE WIRE CONNECTIONS.

 

MOST TIMES THIS FIXES IT.

 

just had a issue and fuse popped and no recharge.( i use a cig lighter alternator volt meter with LEDs)  the igition light dont come on either before start  but truck runs. But not charging!!!  fuse was poppped put new fuse in still the same. Wiggled wire in back of that fuse and started chargin again an IGN light back on before start

[henry]

Thanks for all the responses.  Decided to stick with the fusible link arrangement. Went with the green color ( 40 amps ) as that was slight smaller than the rest of the wire.

  I did like the idea of the circuit breaker. ( ..got one of those in my '55 truck ). Another question: When that red charging light comes on in the dash can one assume that it's usually the alt. gone bad?  Henry