Another Thermotime/Cold Start Valve Issue...Please help

[RPM Resto & Custom]

Now you're past solving the problem and in to trying to figure out what Nissan or a PO did to the car. Like trying to figure out what Pin 21 does. You have a solution for the problem, you can call it solved. Then spend your extra time on exactly how those wires got crossed. Maybe it's a Monday car.

Hahah but did I really fix it or is it somehow bypassing something that shouldn't be bypassed? I suppose it won't hurt anything if it's only active during Start but rather be certain. I'm a stickler for details and doing things the right way whenever possible.

[Captain Obvious]

The CSV should be polarity and connection independent. I haven't taken one apart, but I expect it doesn't matter which connection goes to which prong. You could probably swap the two wires right there at the CSV and I don't think the system would care.

The thermotime on the other hand is most definitely connection specific.

I clipped the 1978 cold start stuff out of the wiring diagram and added a few notes:

The connector pin on the tt which gets 12V on START should be 45

The connector pin on the tt which is connected to ground when the tt is cold should be 46.

I'm not sure what you mean when you say "loss of ground at both 45 and 46". Without more specific measurement definitions... Are you measuring voltage, or resistance? The reason I ask is because you can measure 0V between two things, but that won't necessarily tell you if they are connected together or not.

[Captain Obvious]

And about that shorting to ground to get the CSV to spray with key in START... Is this where you connected to ground? Because if this is what you really did, then something should have smoked. If it didn't, I have no explanation other than someone has messed with the system somehow.

[RPM Resto & Custom]

Captain Obvious.....when I say loss of ground at 45 and 46.....I have a multi meter set to measure continuity with the audible tone on.....one side to ground and one side to whichever pin on the thermotime harness connector I'm probing. As soon as the key goes to Start the tone goes away showing the loss of continuity. Although maybe once the vehicle's voltage passes through it that throws off the meter reading?

To answer your second posts question....yes that is basically where I grounded out the system and got fuel. I didn't short it at the bullet....I did it right at the harness connector for the thermotime...with it disconnected from the thermotime switch.

[Captain Obvious]

Yeah, the vehicles voltage will mess with continuity and resistance measurements. You can not trust that tone to provide accurate results on anything that's powered. If you start adding voltage to a resistance or continuity measurement, seemingly unpredictable things can happen.

So about that short to ground... Is this what made it work? Because I still can't explain it:

Depending on the quality of the ignition switch and all the connectors between the battery and the thermotime connector, you may have gathered up enough resistance along the way such it wouldn't draw enough current to actually smoke, but there's no way putting a ground there as drawn should make the system work as intended.

I'm an hour away....

[RPM Resto & Custom]

Yeah, the vehicles voltage will mess with continuity and resistance measurements. You can not trust that tone to provide accurate results on anything that's powered. If you start adding voltage to a resistance or continuity measurement, seemingly unpredictable things can happen.

So about that short to ground... Is this what made it work? Because I still can't explain it:

Depending on the quality of the ignition switch and all the connectors between the battery and the thermotime connector, you may have gathered up enough resistance along the way such it wouldn't draw enough current to actually smoke, but there's no way putting a ground there as drawn should make the system work as intended.

I'm an hour away....

That's exactly how I grounded it. And if I momentarily ground 46 instead I get smoke. I have to have them right though as 45 gets the 12V signal on start and 46 doesn't when the harness is unplugged from the sensor right?

[Captain Obvious]

45 should be 12V to engine block when the key is in START and 0V to engine block at all other times. You should get these same readings regardless of whether the connector is clipped on the thermotime or not.

And 46?... 46 is a little more complicated, but if you have the thermotime unplugged and the CSV connected, then you should see the exact same thing on 46 as you see on 45 - 12V at START and 0V at all other times.

If you have both the thermotime and CSV unplugged at the same time, 46 should be always 0V regardless of key position.

It makes no sense to me that it would work if you ground 45 and smoke if you ground 46... Are you sure you're not mirroring the numbers when you spin the connector around?

[RPM Resto & Custom]

45 should be 12V to engine block when the key is in START and 0V to engine block at all other times. You should get these same readings regardless of whether the connector is clipped on the thermotime or not.

And 46?... 46 is a little more complicated, but if you have the thermotime unplugged and the CSV connected, then you should see the exact same thing on 46 as you see on 45 - 12V at START and 0V at all other times.

If you have both the thermotime and CSV unplugged at the same time, 46 should be always 0V regardless of key position.

It makes no sense to me that it would work if you ground 45 and smoke if you ground 46... Are you sure you're not mirroring the numbers when you spin the connector around?

I definitely had them correct as far as IDing the connector. 45 showed 58 ohms resistance on the thermotime and 46 none when cold. I then wrote the numbers right on the connector to keep them straight through all this. As stated earlier by someone I tried just swapping my wires over at the csv and it actually didn't make the system operate properly. Only when I swapped them at the bullet connectors did it work right still. I ended up just clipping the bullets and putting new connectors on today and leaving them crossed. It all seems to be working right despite making no real sense and the car starts up like a dream now after being out in the cold for hours. First start today in 45* weather was less than 2 seconds of cranking before it caught.

Thanks for all of the help guys....I can't believe we haven't been able to identify the actual issue or understand why it works the way it works in my case. One of those great mysteries I suppose.

[Captain Obvious]

The 58 Ohms makes perfect sense. Thats the resistance of the heating element in the thermotime. In fact, pretty much everything you have tested and posted makes sense with the exception of the grounding 45 thing, and the swapping the wires thing.

One last thing before I throw in the towel and just revel in your success... Do the pins on your thermotime line up like the picture on EF-32 in the 78 manual?

[RPM Resto & Custom]

The 58 Ohms makes perfect sense. Thats the resistance of the heating element in the thermotime. In fact, pretty much everything you have tested and posted makes sense with the exception of the grounding 45 thing, and the swapping the wires thing.

One last thing before I throw in the towel and just revel in your success... Do the pins on your thermotime line up like the picture on EF-32 in the 78 manual?

Yes....that is how my pins line up...same as the diagram in the manual.