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Two Different Relays For Datsun 510 Headlights?

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It has been challenging to find any relays for headlights in Datsun 510's. I purchased a 25230-89905 relay and I have a 1972, I threw away my 25230-89905 because I am not smart 🙂. So I am looking for some guidance:


25230-89915 is for later 510's and 25230-89905 for early 510's is what I am seeing when I search the internet. In Dime quarterly Volume 7 Issue 3 it speaks about changing the location of the wires in the 25230-89905 in the plug to make them work properly on later 510's.  Can anyone tell me what wires need to be changed?

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I might have a USED one that you can open up & clean like Hainz suggests!  I have done that, soaked them in white vinegar, but I have never filed the points.......sounds easy enough!  PM or email me!  Maybe EMAIL a pic of the wrong one........??


There was a guy on here or the510realm that was making late model black plastic relays with the DAtsun plug on them, but I bought them 2-3 years ago!  Yes there is early & late........I think he was making the LATE one cuz I don't think it plugged into my buddies 1970 510...........??  I'm almost at a point of plugging one in on a project to try it out, almost!


We will be at Road America vintage racing at least two 240Z's again this July & maybe again in September!  You ever get over to RA near Milwaukee?



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Yes, but I don't host & post pics!!  There was a guy a couple years ago that made the later version, using a late model black plastic relay, with the correct Datsun plug, but I can't find his contact!  Same plug for early version, but wires/terminals must be different, cuz it did NOT work on an earlier car.  Without having looked at my wiring diagrams, I'm guessing that the early vs late version probably changed somewhere 1971-1972......??


I'm working on finding a USED relay for slim_jimmy7! 

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Here is a website resource for older Datsun parts - some still available. Also is an archive of nla parts.


This link is for the relay you posted - later style and is what I have in my '72 510 wagon. Lists a bunch of other numbers, none of which mean anything to me.




Here's the relay on my car:



Someone else may be able to find the schematic for the relay and the equivalent newest style. The wiring diagram i have seems like it is a very basic relay.


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1 hour ago, slim_jimmy7 said:

The way I understand it (which could easily be wrong) the insides are basically the same, but the wires don't matchup on the pinout. So if someone had an extra one lying around (I threw my 89915 away a long time ago), and opened it up, I could match it up.


So out of boredom I was looking at the 510 wiring.... seems like from 72 on shows the same wiring .... 6 wires into the relay..... the earlier ones seem to have 2 relays..... 


I could probably figure it out if i had both in my hands.... 


If your wiring is like the schematic in the picture above with the 6 wires I can give you the info to convert it to a standard 5pin bosch relay....


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25 minutes ago, slim_jimmy7 said:

Mine is a 72, so the wiring should look the same as the guide above, I am all ears and have lots of time, we got hit with snow and wind today, so it will be a while in the garage.

If it looks the same and you have all those colors then I'll try to draw a diagram for you to explain it.... give me minute....

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Ok so this a standard 5 pin relay....


85 - BR ( black red stripe) 

86 - GL ( green blue stripe)

87 - RW ( red white stripe)

87a - RB ( red black stripe)

30- B ( black) x2


The black is the ground supply... with the relay at rest this connects 30 and 87a to supply ground to the low beams.... 

When headlights are turned the GL wire supplies power to the relay... BR is the high beam switch(neg) .... when this is turned on it removes ground from the low beam and switches it to the high beam... (switches the 87a to 87) 

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I’m slightly confused as when the Highs are on the low beam is still on also but just switches to the other element in the lamp by switching the ground .I just can’t picture it yet in this diagram you show

30 and 87a would be disconnected when it switches to high so no low beam unless I’m missing something

Edited by banzai510(hainz)
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The relay can select hi or lo beams by a ground switch on the turn signal lever.

The relay is powered by the parking lights on position. No parking lights... the relay remains in the off position

High beams are wired to be ON when the relay is in the off position.

Low beams are wired to be ON only when the relay is powered by the parking lights AND the hi/low switch is in the lo beam position.



Lets say your lamps switch is on low beams.

With everything off the relay is off and the high beams are connected but can't light because the headlamp switch is off.

No matter how fast you pull the headlamp switch to on, as soon as the parking lights are powered so is the headlight relay and as the hi/low switch is set to lo and grounded the relay trips to on, disconnecting the ground to the hi beams and grounding the lo beams. It's faster that the hi beam filaments can light up.


Lets say your lamps switch is on high beams.

With everything off the relay is off and the high beams are connected but can't light because the headlamp switch is off.

You pull the headlamp switch to on, and as soon as the parking lights are powered so is the headlight relay and as the hi/low switch is set to HIGH and NOT grounded the relay remains in the OFF position connecting the ground to the hi beams and disconnecting the ground to the low beams. 


If you do NOT have parking lights you cannot select low beams.


I agree Hainz it is seemingly complicated.


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26 minutes ago, banzai510(hainz) said:


i think I figured it out the double ground is before the relay I assume in the wire harness


i drew out the stock relay from the Haynes manual and replaced the numbering from the black box relay so I think it’s pretty simple 

but like to see a plug and play set up for sale for general pippin sale or home made replacement


I think someone did once....



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Yup, that's the black box relay I bought a few years ago!  Last time that guy listed a small batch of them for sale, stating he doesn't always have them available.


crashtd420.........vintageconnections.com has all of the correct Datsun plastic plugs!  We use them now in all of our repairs & mods in our shop, especially on a restored/painted car..........NEW plugs look killer cool!  If a car is NOT restored/painted, sometimes a good USED plug just looks better to match all the other old plugs!  I spent about $150 on a bunch of NEW plugs, terminals & the two "poke" tools to easily disconnect/dislodge the terminals out of the old plugs.  Only problem with vintageconnections is that they do NOT offer applications, so you have to visually pick & choose the plugs that you want.  I think all of the Datsun's used the simple push together male-female plugs up thru at least the mid 1970's............we are stripping out a 1976 280Z right now & that series car uses the clip together male-female plugs.  You will see what I mean if you go on their website!

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