questions about relays and rewiring

[the nice machine]

i got about half way through restoring all of the wiring clusters on my 1979 620 kc when i realized i would probably be better off starting fresh with a wiring kit ( most likely ez wiring). i just have a little bit more to find out before i order the kit... SO, i've read a few articles in magazines and on websites about using these kits to wire hot rods, starting just from a hollow truck with nothing in it but the engine. so they never say anything about relays other than the flasher unit. but my truck is FULL of relays, right? what about the programmed control unit? the ignition relay? the inhibitor relay? the compressor relay? i swear i have searched the shit out of the forums here on ratsun and everywhere else but i haven't found an answer. i feel pretty stupid for having to ask, but i am pretty new at this stuff so... am i going to be able to just gut ALL of the electronics and start fresh with a kit? or do i have to save all of the relays and use them? i have a bunch of extra relays and stuff from my spare dash, so i have everything i need if that is the case.

please awesome smart ratsun dudes help me out here!!!

 

oh and duh it's not a topic without at least a couple of OICS

\

[Laecaon]

Ok, go through and make a list of all things that can be switch on.

 

Now mark which of these should have its own power (not shared) when turned on due to possibly being too much draw on the wire.

 

These will be relayed. So relay them.

 

The thing is, you will have to figure out where to grab the power leads.

 

You will probably need to incorporate you stock headlight relay, or figure out how to use another.

 

I am trying to think what relays my goon has...

headlight/horn/flasher... I think that might be all.

 

Relays can help make things safer by isolating a circuit. But it is not always necessary.

 

I want to rewire my car. I would use a newer Nissan headlight relay (I think), and newer flasher relays and horn (for an updated look, and reliability?). I also want to change the plugs on my car, as I dislike the stock plugs.

[the nice machine]

hmmm.... starting to make sense thanks.

[the nice machine]

okay a few hours of research later, it seems like i could (in theory) replace all of the relays with the "bosch type" auto relays from radio shack, but every forum i find people say that they short out and only work sometimes, which doesn't sound like fun to me. so maybe i'm stuck using old relays from the jy? my little brain is starting to hurt.

[thisismatt]

okay a few hours of research later, it seems like i could (in theory) replace all of the relays with the "bosch type" auto relays from radio shack, but every forum i find people say that they short out and only work sometimes, which doesn't sound like fun to me. so maybe i'm stuck using old relays from the jy? my little brain is starting to hurt.

The point of relays is to avoid running high current wiring all the way up into your dash/etc and through your switches or low current devices/switches (like the ECU) when really the power only needs to be within a small circuit, but switched on from your dash/etc, or is too high current for a device to control (ECU). Yes, you can change out the relays for the Bosch style relays, but depending on the brand they can be total crap or high quality, so that part is up to you. Also, the normal Bosch relays top out at around 30amps if I recall correctly and sometimes you need higher amperage relays and you'll have to use something different (there are Bosch style relays of higher amperage, but they have larger connectors and/or are physically larger overall).

 

 

The Datsun relays are there for a reason and you should continue to use relays on the circuits they originally came on.

[DanielC]

This is what I would do. Find an accurate electrical schematic of your truck. A factory service manual is your best bet on this one. Get any other electrical diagrams you may be aware of. This may be a Haynes or other manual. If you can get access to Mitchell, or AllData on line data sources, that may help also. There may also be some diagrams somebody else had made, or enhanced. I have found a big PFD file of a 521 electrical diagram from the Factory service manual that somebody broke down into eight separate diagrams with different systems colored, so they stand out. One of the online sources has electrical diagrams for newer cars that when you "mouseover" a wire in the diagram, it highlights the entire circuit in the diagram. Sometimes, the Factory service manual also has separate diagrams or different circuits. I have seen diagrams for the 521 that just shoe the lighting circuit, just the heater motor circuit, just the wiper and washer circuit, just the ignition circuit, just the charging circuit, just the starting circuit. You may not need all the information sources, but it could help.

 

If you break each circuit down to its basic level, it is easy to understand.

 

You may need to make a diagram like this.

This shows the pin connections to the combination meter on a 521.

 

The starting circuit for example, has three main parts. The battery, the starter motor, with solenoid attached, and a key switch. Battery positive connects to the solenoid on the starter. Battery negative connects to the engine, probably the cylinder head, if like my 521. The key switch connects another fused wire, from battery positive, to the small terminal on the starter solenoid, and it grounds back through the starter motor, back to the battery. There may be a neutral safety switch in the key circuit. Especially if the truck has an automatic transmission.

 

Before you decide to "gut" the entire system, find out what each part does. Why is it there? Decide if you need it. I am not sure if you live in an area where they do emissions checks, but if they do, you may have to retain the stock functioning of the truck, and possibly be able to prove it. That is why pre 1975 cars are popular, they are not inspected on a state level. Technically, according to Federal laws, it still has to be there, but so far, there is no Federal inspections.

 

Be aware of different electrical systems interacting with each other. On a 521 for example, when the key is in "start", there is also a second wire that goes to the ignition coil bypassing the ballast resistor.

A similar action happens on a 521 with the four way flashers. The power for the turn signals actually goes through the four way switch, and when the four way flasher is off, the turn signal power is on. So, if you unplug the four way flasher switch, the turn signals will not work. The turn signal switch does not get power. I tell you this because the part you "gut" may be interacting with some other circuit you need.

[erichwaslike]

wat is wrong with ur factory harness? id never use an ezwire on something like a datsun where ur not gutting all the factory circuts. if ur looking for it to function just like b4 and ur new at wiring just get the factory schematic and make sure ur harness is how it shood be. i combined 3 factory harnesses on my 411 and it was way easier than the multiple ez wiring harness's ive done in resto projects(48 fleetline, 50 ford busines coupe, mustangs, and the multiple offroad cars too)

 

the easy wiring is good for hot rods but ur 260 has too many creature comfort and other circuts that arent on an ez wiring

[the nice machine]

The point of relays is to avoid running high current wiring all the way up into your dash/etc and through your switches or low current devices/switches (like the ECU) when really the power only needs to be within a small circuit, but switched on from your dash/etc, or is too high current for a device to control (ECU). Yes, you can change out the relays for the Bosch style relays, but depending on the brand they can be total crap or high quality, so that part is up to you. Also, the normal Bosch relays top out at around 30amps if I recall correctly and sometimes you need higher amperage relays and you'll have to use something different (there are Bosch style relays of higher amperage, but they have larger connectors and/or are physically larger overall).

 

 

The Datsun relays are there for a reason and you should continue to use relays on the circuits they originally came on.

 

 

 

 

This is what I would do. Find an accurate electrical schematic of your truck. A factory service manual is your best bet on this one. Get any other electrical diagrams you may be aware of. This may be a Haynes or other manual. If you can get access to Mitchell, or AllData on line data sources, that may help also. There may also be some diagrams somebody else had made, or enhanced. I have found a big PFD file of a 521 electrical diagram from the Factory service manual that somebody broke down into eight separate diagrams with different systems colored, so they stand out. One of the online sources has electrical diagrams for newer cars that when you "mouseover" a wire in the diagram, it highlights the entire circuit in the diagram. Sometimes, the Factory service manual also has separate diagrams or different circuits. I have seen diagrams for the 521 that just shoe the lighting circuit, just the heater motor circuit, just the wiper and washer circuit, just the ignition circuit, just the charging circuit, just the starting circuit. You may not need all the information sources, but it could help. If you break each circuit down to its basic level, it is easy to understand.

 

The starting circuit for example, has three main parts. The battery, the starter motor, with solenoid attached, and a key switch. Battery positive connects to the solenoid on the starter. Battery negative connects to the engine, probably the cylinder head, if like my 521. The key switch connects another fused wire, from battery positive, to the small terminal on the starter solenoid, and it grounds back through the starter motor, back to the battery. There may be a neutral safety switch in the key circuit. Especially if the truck has an automatic transmission.

 

Before you decide to "gut" the entire system, find out what each part does. Why is it there? decide if you need it. I am not sure if you live in an area where they do emissions checks, but if they do, you may have to retain the stock functioning of the truck, and possibly be able to prove it. That is why pre 1975 cars are popular, they are not inspected on a state level. Technically, according to Federal laws, it still has to be there, but so far, there is no Federal inspections.

 

 

wat is wrong with ur factory harness? id never use an ezwire on something like a datsun where ur not gutting all the factory circuts. if ur looking for it to function just like b4 and ur new at wiring just get the factory schematic and make sure ur harness is how it shood be. i combined 3 factory harnesses on my 411 and it was way easier than the multiple ez wiring harness's ive done in resto projects(48 fleetline, 50 ford busines coupe, mustangs, and the multiple offroad cars too)

 

the easy wiring is good for hot rods but ur 260 has too many creature comfort and other circuts that arent on an ez wiring

 

okay, guys. the reason i am considering "gutting" my electrical system is because i have already redone most of the wiring, shit was all mismatched and hacked up from a previous owner. it still develops new glitches on an almost daily basis. and i do have at least one correct wiring diagram for my truck, and i have traced every line. i've tested every terminal, everything works, but everything likes to stop working on occasion, and i'm not into that. FRANKLY I AM TIRED OF DEALING WITH STIFF OLD ROTTEN FUCKING WIRES.

i just bought a 1980 720 (been studying the wiring diagram on that too), i am planning to put my 620 body on it, and trying to combine the two systems adds to the headache. and yes i am trying to keep it functioning the same, it passed california emissions two years ago. i don't want to leave out a relay that i need, i'm just trying to figure out good replacement relays without having to do the normal "rare datsun part ebay craigslist pay too much" hustle. i have some old ones but they are 30 years old so i don't really have much faith in them. anyways, i am tired, i've been up all night drinking too much coffee trying to learn stuff, i don't think i have the energy to learn this multi quote shit today. i already did what you guys said.

[the nice machine]

also i scan the diagrams from books into a pdf, so i can zoom in super close, it's pretty handy.

[ggzilla]

The 620 harness I got fromt eh wrecking yard was perfect, like brand new almost, no corrosion, certianly not brittle

 

There are few relays on a 620. None of the ones you mentioned. NO programmed control relay. No inhibitor relay, etc.

 

Adding MORE relays will decrease relibility. As Matt said, keep the relays that already exist, they are there for a reason. Keep your wiring simple for more reliability.

[the nice machine]

The 620 harness I got fromt eh wrecking yard was perfect, like brand new almost, no corrosion, certianly not brittle

 

There are few relays on a 620. None of the ones you mentioned. NO programmed control relay. No inhibitor relay, etc.

 

Adding MORE relays will decrease relibility. As Matt said, keep the relays that already exist, they are there for a reason. Keep your wiring simple for more reliability.

 

actually, the 1979 does have an inhibitor relay ( it's useless though because all it does is keep you from being able to start your engine if you don't have the clutch pressed in). and the 79's with air conditioning did have a programmed control unit, i believe it was to control the fuel pump, which also only came on air conditioned models. also the wiring diagrams for 1977-1979 of 620's varies greatly. so if you want a harness for a '79 a '77 isnt even close to the same thing. and there aren't many 79's out there to choose from.

[the nice machine]

 

and yes ggzilla i would like a system much simpler than this.i actually get jealous when i look at wiring diagrams for early 70's 620's.