No Power!

1980-1986 Datsun 720 forums. All 720-specific topics and discussion can be found here.
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brianzero
Posts: 53
Joined: Wed Feb 03, 2010 6:43 am
Car: 1986 Nissan 720 4x4 Regular Cab 265,000 mi! (Gasser unfortunately)

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Im having a little problem here, which is I have NO power. I try to start the truck, and nothing happens. This is what checks out OK:

New Alternator.
Getting power to the alternator.
Battery has full power.
All wiring from the positive side of the battery are good.
Fusable links are good.
My fuses at the fuse box are good.

Is there a relay or something else that could cause a total power blackout?


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breadbox
Posts: 8549
Joined: Tue Oct 17, 2006 4:09 pm
Car: 89 Nissan 240SX
89 Koop
84 720 4x4KC
Location: Va Bch

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Starter?
Distributor?
Plugs?

Ignition?

Could be alot of stuff preventing or just not sparking.

synack7350
Posts: 364
Joined: Sun Jan 09, 2011 3:08 pm
Car: nissan '83 720 king cab pickup 2wd 2.4L Z24
Location: Boaz, AL

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your headlights and other gizmos work? if so then it sounds like either your starter solenoid isn't getting juice or its bad. If nothing is working no lights nothin, then its between batt / alternator, and fuse box. oh one more thing if you are not getting lights or nothin check your main ground from the batt. that'd cause it

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brianzero
Posts: 53
Joined: Wed Feb 03, 2010 6:43 am
Car: 1986 Nissan 720 4x4 Regular Cab 265,000 mi! (Gasser unfortunately)

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Nothing works, like there is no battery! My multimeter is telling me that the ground from the battery is 13v. Im getting 13v to the alternator and 13v to the starter.

Is there a relay that controls the starter circuit?

synack7350
Posts: 364
Joined: Sun Jan 09, 2011 3:08 pm
Car: nissan '83 720 king cab pickup 2wd 2.4L Z24
Location: Boaz, AL

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no its pretty much has to be the ground. remove ground wire from battery and where it connects to the frame and check continuity through the wire. if its good reinstall and make sure it is making good metal on metal contact to the frame. thats the best place to start. just cause there's power at the battery doesn't mean its getting everywhere else. ground affects every component so it makes sense that is where your issue would be.

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brianzero
Posts: 53
Joined: Wed Feb 03, 2010 6:43 am
Car: 1986 Nissan 720 4x4 Regular Cab 265,000 mi! (Gasser unfortunately)

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Im going to yank off the negative cable from the battery to the body and make sure its clean and conductive. Ill let you know if that solves the problem...

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brianzero
Posts: 53
Joined: Wed Feb 03, 2010 6:43 am
Car: 1986 Nissan 720 4x4 Regular Cab 265,000 mi! (Gasser unfortunately)

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synack7350 WINS the diagnosis prize! The truck runs!!!

The negative engine side of the 'battery to engine' wire where the negative connects to the engine looks like it had arc welded its self into destruction. I had to sand and reshape it all to get it all repaired. I also resoldered all of the positive connections near the fusable links for good measure.

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breadbox
Posts: 8549
Joined: Tue Oct 17, 2006 4:09 pm
Car: 89 Nissan 240SX
89 Koop
84 720 4x4KC
Location: Va Bch

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Nice. Good job Synack.

synack7350
Posts: 364
Joined: Sun Jan 09, 2011 3:08 pm
Car: nissan '83 720 king cab pickup 2wd 2.4L Z24
Location: Boaz, AL

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thanks I was actually an industrial electrician for 5 years before I joined the army. Now I'm studying to be a physicist there's not much electrical I can't finger out. printed circuit boards are beyond me but anything else I can trouble shoot pretty quick.

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brianzero
Posts: 53
Joined: Wed Feb 03, 2010 6:43 am
Car: 1986 Nissan 720 4x4 Regular Cab 265,000 mi! (Gasser unfortunately)

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Dude, youre like the psychic electrician. That problem was so obvious that I didnt see it. I didnt think that it would be an issue, the ground, but it was. Too bad youre in Boaz, I'd buy you as many beers as it would take to get you drunk as a reward.

synack7350
Posts: 364
Joined: Sun Jan 09, 2011 3:08 pm
Car: nissan '83 720 king cab pickup 2wd 2.4L Z24
Location: Boaz, AL

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haha thanks man.


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