2nd Starter Wire in Nissans Does What?

Kidding aside..it would have nothing to do with sending more juice to the starter. The starter is connected to the battery. The "crank" wire from the ignition switch goes to the starter relay or solinoid if you prefer.

That 2nd starter wire must have some function. I have heard from others also that it is for cold start but knowing that in itself does not really answer the question of "why???"

Anyone actually know since I am also curious now. Thanks. If it is for a flux capacitor perhaps the Delorians also used a second starter wire but it also ran on garbage.

Here's how the cold start valve/thermo time switch works:

The thermo-time switch has a metal contact arm inside which is wrapped with a heating element. When it's cold, the arm contacts a ground connection. When you turn the key to start (the cold start valve ALWAYS receives power when the key is in start, and ONLY when the key is in the start position -- temperature is irrelevant as far as the cold start valve itself is concerned) 12v is sent to the cold start valve. If the thermo-time switch is cold, then the thermo-time switch grounds the cold start valve, allowing it to inject fuel. When the key is "on" the heating element in the thermo-time switch is warming up and slowly bending the contact arm, and so once it gets warm enough, it breaks contact and no longer grounds the cold start valve, shutting it off.

However, this applies only when cranking. The cold start valve never receives 12v when the engine is running, i.e. when the key is in the "on" position, only when the key is in the "start" position. So, to answer your question, no, the cold start valve is probably not staying on, unless you've got some weird wiring.

And the thermo-time switch does not supply 12v to the cold start valve, it merely supplies a ground for the cold start valve.

I looked through several Nissan/Infiniti service manuals and couldn't find any reference to the 2nd starter wire.  It isn't listed in the power/ground diagram of the car that has all the other ignition/accessory/starter wires on it.

However, I did notice that the DRL system found on Canadian Nissan's is reset by the 2nd starter every time the car is started.  This circuit is left off of UDM vehicles though.

Interesting.....

I'm not sure the cold start valve is totally accurate.  Where is it injecting this extra fuel?  During cranking, modern day Nissans batch inject/fire during cranking, so I don't think extra fuel would be beneficial when its cold.

I'll look through the manual for a cold start valve though and see if I can find out anything else about it.

With copper prices soaring perhaps they will get rid of the 2nd starter and use one starter wire like almost everyone else.

But anyhow still seems to be some mystery to this.

If there was a 'cold start injector' on a newer Nissan vehicle I'm 99% positive it would have made it in to the service manual.  The only year listed on that page is somthing about a '77 Westy. 

I don't doubt that this technology was used on cars, I just have a hard time believing Nissan is using it today, without documenting it in their service manuals!

I'm going to make some posts on some Nissan specific forums and see if I can get any answer.

It's interesting .. clearly it does something, b/c people have reported on this forum that their Nissan will not remote start appropriately in the cold  -- some investigation is done... and they discover the 2nd start wire has not been supplied +12volts.

I'll be VERY interested to know what it actually does, thanks for these replies and the "investigation effort."

<if the Delorian DID in fact have a 3rd starter wire.. it must have been for the flux capacitor... w/o a doubt -- I'll email Delorian (if he's still alive) and see what the verdict on that is...>