fuses on a 1980 720

1980-1986 Datsun 720 forums. All 720-specific topics and discussion can be found here.
FiveSeventyZee
Posts: 18
Joined: Tue Jun 30, 2009 8:59 pm
Car: '72 570z & '80 720

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so I'm still having troubles with my truck. the fuse closest to the driver pops instantly everytime. it's a red 10amp fuse. does that sound like the right fuse for that position on the fusebox? can anyone tell me what that fuse is for?


flinterman2000
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Joined: Mon May 04, 2009 5:32 pm
Car: 2000 Nissan Wingroad, 85 Datsun 720 Pick Up.

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Fuses are a safety for the truck. they blow instead of your truck burning. something is going to ground. get an electrician check the problem.

dogred
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Joined: Sat May 16, 2009 10:15 pm
Car: 1983 D720

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Get your hands on a multimeter and set it on ohms. Place one lead on bare metal (screw heads are very good). Place the other lead onto the connection of the fuse. (one side only first, then the other) This should tell you which side of the circuit is grounded.

Most likely it will be on the load side, since most of the power is connected at a common point.

flinterman2000
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Car: 2000 Nissan Wingroad, 85 Datsun 720 Pick Up.

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Iagree, but it dosen't identify the location of the short. several systems use a common fuse. an auto electrician through experience would be able to hi-light the location of the short.

FiveSeventyZee
Posts: 18
Joined: Tue Jun 30, 2009 8:59 pm
Car: '72 570z & '80 720

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does anyone know what that fuse is for though? my mechanic said it was the main engine fuse but 10 amps seems kinda low for that and i don't see how he would know. he isnt a datsun expert so i feel like it might not be the main engine fuse.

FiveSeventyZee
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Joined: Tue Jun 30, 2009 8:59 pm
Car: '72 570z & '80 720

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does anyone know which fuse this is and if it's supposed to be a 10 amp?

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PEZi
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for the 1980 model it is supposed to be a 10Ait is for the engine control system (auto choke heater, fuel cut solenoid, etc.)

FiveSeventyZee
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Car: '72 570z & '80 720

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thanks, do you know what the other 10a's are for?

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PEZi
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for yours... the second 10A is the horn and clock... the third is for the lamps (tail, license, clearance side markers, illumination and room)

FiveSeventyZee
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Joined: Tue Jun 30, 2009 8:59 pm
Car: '72 570z & '80 720

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okay thanks. I took out a bunch of loose wires that were an attempt at wiring in a stereo by the previous owner. they were just loose with bare leads. I'm hoping one of those wires was causing the short. I think I'm gonna use the horn fuse to test because my horns don't work anyways.

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PEZi
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lol... horns on these trucks sound gay anyway

FiveSeventyZee
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Joined: Tue Jun 30, 2009 8:59 pm
Car: '72 570z & '80 720

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lol, well mine hasn't worked since i got it and i never use my horn anyways. to me, a horn is useless unless someone's at a green and not moving. when someones coming at me its easier to me to move the car than to move my hand off the wheel to use the horn

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PEZi
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the horn is one of my deletion projects... lol

its so useless and sounds so terrible

FiveSeventyZee
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Car: '72 570z & '80 720

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i definitely agree, horns arent needed

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PEZi
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especially on a 'track car' lol

FiveSeventyZee
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Joined: Tue Jun 30, 2009 8:59 pm
Car: '72 570z & '80 720

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well i still dont know where the short is. its behind the dash somewhere. instead of trying to search some more i decided to rewire it yesterday. i put a new wire going from the back of the fusebox to the right side of the car just before the wires enter the engine bay. tested the power with a voltmeter and was getting 12 volts to the fuel cut solenoid which is the farthest item on the circuit, so i set it down and was done for the day.

last night i realized i forgot about the auto choke relay and the clutch switch (which are both on the same circuit) so today i wired those in and it seems to be working now. it seems to be idling better. before it was idling above 2k now its down to about 1.1-1.4k rpms. does that sound right? or should it be idling lower still?

flinterman2000
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Car: 2000 Nissan Wingroad, 85 Datsun 720 Pick Up.

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Z24or Ka24 usually idles at 900 to 1k, so its ok where its at.


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