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521 temp sender.... Common Datsun problem??


Jocucumber

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Hello fellas... First Post!

 

I recently bought a nice little 71' 521 and the temperature gauge doesn't work. So I replaced the temperature sensor and it wouldn't start, so i think i maybe i broke a wire at the dizzy with my dumb hands or something. Everything looked fine, so I checked for fire at the coil. no spark. I look at the points, trace every wire i can, even replaced the coil with a spare i had just in case the coil randomly went bad. Still no spark. 

 

I never in a million years thought replacing the sensor would make a difference, but I pulled the temperature sensor wire and it cranked right up! Plug it back in, No Start.  I cant see in any diagram where a short in the temperature sensor wiring would affect spark, but who knows

 

Ive lurked on this thread for years and I searched all through alot of posts and never heard anyone having a similar problem, so I registered just to ask if this is something you guys have seen before. 

 

Thanks

          

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Did you test the wire from the sensor to the gauge to make sure it's the correct one? Sounds like you may have an ignition wire shorted to the temp sending wire. 

 

Also, you'd probably get more response if you posted this in a truck or electrical thread rather than starting a thread for one question.

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Did you test the wire from the sensor to the gauge to make sure it's the correct one? Sounds like you may have an ignition wire shorted to the temp sending wire.

 

Also, you'd probably get more response if you posted this in a truck or electrical thread rather than starting a thread for one question.

 

Yes it's temperature sensor wire, but my voltmeter is broken so my testing ability is limited.

 

And I thought I was posting in the 521 thread... I didn't know if posting there would get more eyes... thanks for the advice

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Modified the title so the search engine will find this for future 521 owners with similar problem.

 

 

 

 

Yeah it's the yellow wire

 

No.... has to be Yellow with White stripe for the water temp sender. Yellow/Black (stripe) is the oil pressure sender.

 

521wires.jpg

 

 

The temp and fuel gauges share a common power supply and have nothing to do with the ignition.

 

Does your fuel gauge work properly?????

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later 521s have a dual point system so you sure you got the correct wire on there?  the 2nd set points I think is blk/ yellow. this is the side with the smaller capicitor on side of the distributor. the drawing shows a blk yellow wire but I cant remeber As I run a Pertronix ignition unit now

 

 

sender wire is a solid yellow if i remeber right  on this drawing posted shows it yellow /white. Maybe the white turns more solid yellow over time as it get dirty

 

 

 

so what I can remeber the blk yell by the distributor is the 2nd set of points

yellow is the temp sender.

 

yes thre is a yell/blk on the oil sender but this is obvious thats not it

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ok give me minute to send pics... first time remember.

 

second... Im pretty excited I got responses from Wayno and Datzen... im a little honored

 

totally solid yellow wire. and i now im a newbie to the forum and this particular Datsun, but im a long time mechanic that possibly thought this might stump you guys. 

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That looks like the correct wire, I don't believe anything is mixed up, if you ground that wire out and nothing happens, meaning the gauge doesn't go to full hot, then something is wrong, either the wire/wire end is bad, or the gauge is bad as you said the fuel gauge works, so it is not the power regulator in the instrument cluster.

You will have to find another way to test the gauge.

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Put the old sender back in it?

 

 

https://goo.gl/images/49EMO7

did that too... it runs and starts fine with the old one.

 

also i started it with new one unplugged and then connected it in while it was running. it stayed running and now starts and runs with it connected, but of course the gauge still doesnt work which makes me feel like connecting while running killed the new sensor idk..

 

so somewhere between the sensor an

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