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Removing unnecessary stuff from engine bay


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Fitting another engine in my 620 so might as well clean engine bay a bit. According to my shop manual there are a few relais that i don't think i need anymore.

Car was automatic now manual, car had anL20B with carb now an EFI setup.


So can i remove the inhibitor and auto-choke relais and wiring? Anything special about it or just follow the wires and remove?

Edited by Eric
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3 hours ago, 5t341tH said:

i removed all of mine besides the horn and the ignition switch relay


yes thats what i was thinking but what to do with the wiring, pretty sure i just can't cut it all and that is?

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The wiring is going to be difficult to deal with, if you want to remove unnecessary wires. 

Wiring for the starter has to stay.  The alternator wiring can stay the same, or the alternator may be changed to an internally regulated alternator, if your truck had an external regulated alternator, or you can keep the old alternator, and external regulator, if you want. 

The EFI engine is going to need wiring added.  The EFI engine may have an electric fuel pump, that wiring will have to be added.


The problem is the wires for the engine ignition, charging, starting, some emission controls, carb choke heater are all buried in the engine bay wiring harness with lights, the horn, possibly wind shield wipers, and washer and other accessories.  


The wires in the harness may be wrapped up with a sticky tape, and to remove the wires you do not need you have to unwrap the tape, remove those wires, then add wires you do need for the new EFI engine, and wrap the harness up again.

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i planned on removing all the no longer needed wiring and relais, everything is old and crumbled and potentially a problem in the future. the new engine comes with its own engine loom and needs to be connected to the car.


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19 hours ago, Eric said:


yes thats what i was thinking but what to do with the wiring, pretty sure i just can't cut it all and that is?

i did an engine swap and used a standalone wiring loom as well. I just kept all the wiring needed for the starter relay and horn. I cut open the original loom and removed all the old wiring i did not need

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  • 1 month later...

Since my 620 was born with an automatic transmission its seems to have a lot of no longer needed stuff.

The inhibitor relay has wires going to a 'check connector'  what does that do? or doesn't it do anything and its there to check if other stuff works?

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It's a very primitive way to plug into the harness by Nissan dealerships to diagnose engine electrical problems.


Be sure to use the wire diagram for your year truck. There is a vast difference between the up to '77 and the '78 and on trucks. Every year is at least slightly different.

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Well most of the unused stuff form the engine bay loom is gone now.

Found a few surprises, 




melted from firewall to front combination lamp..






this should be the ignition relay. What does it do? Do i need it after sr20de swap and if i still need it can i replace it with a modern one that does the same?






this should be horn relay, can i change that for a more modern one and if it is possible how do i know what sort i have to use? 

Edited by Eric
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