total sudden electrical failure

[kenward1000]

71 240z owned for 5 months.  Been on two 900 mile rallies, driven daily, been running great.  Decided to re-check vacuum pressure, after replacing two leaking hoses (block to intake manifold, intake manifold to brake booster).  Started car, let it warm up.  Shut it off, plugged in vacuum gauge hose.  Car won't start.  Won't crank, no turn signals, no horn, no nothing.  Even though I thought that plugging in the vacuum gauge couldn't possibly cause the problem, removed it and still no electrical power.

Battery is 2 years old, measures 12.75vdc.  Searched all forums for similar issues.  Charged overnight, still no electrics.  Jumped from a known good battery, still no electrics.

No voltage detected at any fuse in the panel, all fuses good.  I'm electrically competent.  Would appreciate any tips on where I can look for potential failures.

[siteunseen]

My alternator killed my '72. No gauges moved when the ignition switch was in ON position.

Edited November 1, 2019 by siteunseen

[kenward1000]

Where is this alternator fuse located?  Thanks

 

[siteunseen]

Just now, kenward1000 said:

Where is this alternator fuse located?  Thanks

 

It was actually my alternator. Popped the IGN fuse killing everything else.

[kenward1000]

Where is the IGN fuse located?  Thanks

[kenward1000]

Wait, do you mean the 20A IGN fuse in the fuse panel?  Already checked and known good.

 

[SteveJ]

Check your fusible link. I will post a photo later. It's suppertime. 

[siteunseen]

On my car the alternator went out. It killed everything but it did burn that fuse you're talking about, in front of the shifter. 

Have you checked the spade plug on the starter?

When suppertimes over Steve will figure out you problem. 

Edited November 1, 2019 by siteunseen

[SteveJ]

Okay, the fried egg sandwich and tater tots hit the spot. Thankfully, I found a photo on my computer so I don't have to go out to the garage. I'm getting old and lazy.

You can find it here: http://www.zzxdatsun.com/catWiring.php. It's part number WH-03.

 

[SteveJ]

@zspert Are you still just taking checks, or have you moved up to Paypal? I think @kenward1000 will probably be contacting you soon about a fusible link.

[kenward1000]

Aha!  That image led me to the problem spot.  Now I can see the "fusible link", which looks very much like a length of black wire.  The "fusible link" provides +12vdc to the wiring harness, through the plastic connectors. 

The tab of the connector on the harness side had broken off sometime in the past.  So the DPO had put a wrap of duct tape around the connectors to hold them together.  For some reason there's no slack in that wire on my car, so the connectors eventually pulled apart.  When they were no longer touching, that fact was covered up by the duct tape.  My "fusible link" shows continuity.  

Zip ties and clear heat shrink to the rescue, all electrical power restored, car starts.

Should get a spare starter "fusible link" to carry with me on rallies, where a single-point failure means an expensive flatbed home.  On the harness side, need to lengthen the wire by 2" to prevent tension strain on the connector and find a new connector end that has a functioning tab.

Are there other "fusible links" in the wiring harness?

Thanks for the replies!

[SteveJ]

That's the one and only fusible link in a 240Z. I forgot that you can get the fusible link here, too: https://www.thezstore.com/page/TZS/PROD/12-4332