Firewall Relay Help
 

Can anyone identify what this relay is for? I notice it will randomly click off/on for no reason while the car is on or off with accesory on. Every time I connect the battery it clicks on as well.

I have looked in Haynes and FSM... I cannot find this for the life of me.

This is a '73 that came with AC... Manual trans.

Thanks!

That might be the interlock relay. Not sure if there's an interlock system on the '73 240Z but on the '74 early 260Z, that's right where it goes and what it looks like.

1. Identify the wire colors on the wiring harness side.
2. Is any part of the Nissan part number visible on the relay?

I looked at Datsun 240Z/260Z Electric Unit & Switch (1) (To Nov.-'74).
The closest part I could find in that location is part number 28820-N3300, ASSY-AMP INTERMITTEN. That would be an amplifier for the intermittent wipers. The information from 1 and 2 could confirm or disprove it.

Steve - that assembly is located inside the cabin on a bracket with the horn relay and other odds and ends.

I don't think 240Z's came with the interlock relay? Those were on 260Z from what I read.

I will have to take a look at the wires... I believe there were 3 black and 1 green. Unfortunately the numbers wore off and a are extremely hard to read. The car resides at my parents garage, so I won't get to it until this weekend.

It appears to be exactly like this, but these are under the passenger side dash as well: http://www.classiczcars.com/uploads/...5079542764.jpg

I guess I could always disconnect it and see what doesn't work? I remember when I bought the car it was disconnected, and I plugged it back in!

I only mentioned that relay because it is show apart from the kickpanel in the parts fiche.

On the other hand, let's assume that one of the wires is black/white. That would make it plausible that it is the Throttle Opener Relay. This relay would only be needed if the car has the original flat top carburetors and associated plumbing & wiring.

Be sure to get the color of the stripes, too. The wire colors on the relay are not important. The wiring harness wire colors are the ones we need.

Sounds good, I will take a close look. The flat tops have been replaced to round tops... perhaps this is why it was disconnected. I will keep you posted!

Paul, you are too funny. I decided to do a little digging and found this photo on another forum. The post was from 2005! I see you've already been digging around. At that point I stopped cuz you are already doing the same searches that I would do.

Your question definitely has my curiosity going as that relay seems to be used in a couple of places on the cars as you point out. It is a fairly general purpose relay so that makes sense.

OK, no interlock on the 240Zs. I replaced the flat-tops on my 260Z with round-tops as well. Hmmm ....

Yeah, I have been looking all over for an answer and probably scoured 100's of images/posts.

So the wires coming off the wiring harness are:

• 3 black with white stripes (maybe tan)
• 1 all green

There's a throttle opener relay referenced in the engine tune up section of the '73 FSM. Its wires are BW, BW and BY (yellow instead of tan?) plus a GB. If you missed the black stripe on the green wire, we've got a winner.

This relay is pretty specific to the flat top carbs and is used during deceleration to keep the throttle open just a tad for emission control and it's only on the manual transmission cars.

Conversion to the round tops pretty much eliminates it. That happened to me.

Section ET of the FSM, page 13 begins the discussion. You can also see it in the Body Electrical section BE on page 2.

Hey! That must be it then! The "Throttle Pener Relay." The wires are a little faded, so the coloring must have faded, hence the white/tan.

Should I leave it connected or disconnected? Obviously it has no use, but does it do any harm connected? Like I said, when the ignition is on, I will hear it randomly clicking on/off.

I attached the FSM page you referenced and highlighted it.

Thanks! :armata_PDT_37:

I'd personally remove it completely. It will just draw some current and is an unnecessary potential problem.

Kind of like a wisdom tooth. Not very useful but if it gets infected, it is very bad.

Ironically I still have all 4 of my wisdom teeth...

Yeah, me too.

It's a lot less trouble to eliminate the relay than it is to remove wisdom teeth.

Besides, you now have a spare relay for the one in the cabin. Mine went into a box labelled "Spare electrical stuff".

Not here for the relay, but hey to the wisdom tooth club, we are bringing it back!

The relay would be off topic at this point.