Cold start valve power supply

[lmcchesney]

What is the 12V source for the cold start valve? It seems from the schematic, that the Thermo Switch functions as a ground supply to the cold start valve. When the temp increases, the thermo switch opens and interrupts the ground to the cold start valve. From the schematic, the cold start valve gets its 12V supply from pole II of the regulator plate. Is the 12V supply shut off when the temp increases or is it always on?
Thanks,
L.McC

[pbanders]

The +12V for the CSV is present only when cranking.

[lmcchesney]

Thanks Brad.
What shuts off the 12V supply? Is it keyed to the ignition switch?

[Dave at Pelican Parts]

The yellow wire that goes to the starter is the same wire that goes to the CSV. (The connection is made inside the relay board, but it's the exact same circuit.) So when you release the key from "cranking", the +12V to the CSV stops.

--DD

[lmcchesney]

Maybe that is the yellow 12ga wire I found not connected to anything and cut off on my wiring harness. So as I read the schematic, the yellow wire recieves 12v from the starter during cranking, delivered to the regulator plate. From the regulator plate it is connected to the fuel injection harness via contact 18 and feed to the cold start valve. Is this correct?

[Dave at Pelican Parts]

What year and displacement engine do you have? If it's a 1.8, then I believe the yellow wire plugs into the four-pin connector on the relay board. And it does carry the "cranking now" signal.

You've sort of got the "meaning" of the yellow wire I was talking about backwards. Power goes from the battery to the ignition switch. When you turn the key to "start", the switch connects this power supply wire to a yellow wire. That wire carries power from the switch to the starter, causing the solenoid to trip and the starter motor to crank.

There are some things that happen along the way. On a 74 (and some 75s), there is the Dreaded Seatbelt Interlock Relay, which can disconnect that yellow wire if it thinks your seatbelts are not fastened. And on all cars, the yellow wire plugs into the relay board, the signal goes through the board, and then goes from the board to the starter. There are a couple of other connections into that circuit that happen inside the board. One of those connections is used to power the CSV.

So the yellow wire doesn't carry anything "from" the starter--it carries power "to" the starter, and other things tap into that same power.

A page for you... Look through the diagrams on it.
http://www.pelicanparts.com/914/914_electrical_diagrams.htm

If that yellow wire is in the engine harness--the one with the 12-pin plug that plugs into the right-rear of the relay board--then it is the wire to the starter. That wire goes through the rear engine tin and has a female spade terminal on the end of it, and that terminal plugs onto one of the male spade terminals on the starter solenoid. (All of those terminals are the same, electrically.)

Aaaah, the joys of trying to resurrect a basket-case car.

--DD

[lmcchesney]

Thanks as usual Dave. The wiring harness is off of a 72 1.7L D-jet. At least that is what the car was identified as. I believe the wire was not connected to the selinoid and was not allowing cold start augmentation.
L. McC

[Dave at Pelican Parts]

If the wire was not connected to the solenoid, then it wasn't allowing the starter to work. That wire does not specifically carry the CSV power, it specifically carries the "make the starter crank" power. The CSV is incidental to it.

If the starter worked in the car with this wiring harness, then I believe someone did some re-wiring.

--DD