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IdahoKidd

water temp sensor/thermotime switch ID

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I finally have this car up and running but the cold start injector doesn't fire when hooked up. It does fire when triggered when tested. The engine temp doesn't seem to come up above 120 according to the gauge. I noticed this evening that the wiring connectors are interchangeable on the two. It is possible that the wiring connector for the thermotime is connected to the water temp sensor and vice versa. Can anybody tell me how to tell by the wiring, where it goes or colors or any other identifier to see if I have them crossed.

Also, the tach doesn't work nor does the clock. Coincidence or related?

By the way, the z car will not run when the wires to the ignition module are hooked up backwards............. Gotta love those PO's.

Thanks,

Leonard

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From the AWFUL 1977 280Z wiring schematic in my Haynes Manual: -

Water Temperature Sensor, Black & Black wires.

Thermo Time Switch, Green & Green wires, both of which go to the Cold Start Valve terminals 45 & 46.

That's all folks, I went crossed eyed at that point:cross-eye:cross-eye

Edited by Nissanman

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The tach and clock problem wouldn't be related to the thermotime/water temp senor wires being switched. Nor would the temperature gauge reading as it has it's own sensor, the one with the single bullet connector. Which ignition module do you have? If it's the matchbox on the side of the dist., then it also came from a ZX because a 77 wouldn't have had that type of dist. from the factory.

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I figured out the connectors. All of the confusion comes from the fact that both connectors had black wires. At some point in the cars life, the connector to the thermotime switch had been replaced/spliced with a new one with black legs. The harness was then rewound/taped up (good looking repair). A bulge 10 inches up the loom gave suspect and sure enough, opened it up and green wires.

Thanks for the help!

PS-sblake01; took the car an auto electrical shop and found the ignition module wiring was reversed as well as the fuel injection harness. Took the e12 distributor out and put in the correct one. The tech there was the one that thought the motor was not correct for the year but thought it would be just fine. It actually runs really well, just hard to start. Thank you for your time and information.

Leonard

Moscow, Idaho

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Keep us posted. How did you get around the three row pulley problem? Nissan did it by moving the fan on the ZX forward which is not an option on the 280Z.

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I removed the center bolt from the cranshaft, took out the six little bolts that held the 3rd pully onto the crankshaft and the pulley easily separated from the rest. I then put the center bolt back into place, torqued it to the best of my ability and away I went. I wasn't nearly as complicated as it seems to have been in a different post. Again, I am not sure specifically what motor is in this car but believe more and more that it is 82-83 zx. I do know that putting in ac or anything requiring the use of that 3rd pulley is going to cause grief.

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AC and power steering made three row pulley necessary on the all the 810s and all the ZXs. Since the S30 didn't have power steering a two row pulley was all that was needed even with AC.

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Well it all makes since, the replaced engine was from a zx. I am tickled to know I can still put the ac in. I have a donor car that has the completed stock set up, so someday...... BTW, the car starts and runs incredibly well. I am tickled! A few little bugs, the tach and the clock mostly. When I get more time I'll fool with them.

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Okay all you forum Nazis, I know that I'm bring up a thread from the dead but it pertains to my question. (And yes, I've searched.)

I've recently had to replace my thermostat housing on my '75 280z. I didn't mark which connector goes to the thermotime switch and which goes to the water temp sensor. I've tried the '75 & '76 wiring diagrams, but it's no help because the wires for both years are white/white to the thermotime and white/white to the water temp.

One of the sets of wires has a 1 inch wide strip of red tape wrapped around it near the bullet connectors. Can anyone tell me which sensor the marked set of wires should connect to?

Thank you,

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The thermotime switch wires run to the cold start valve. You should be able to see the wires without tearing too much apart.

Edited by Zed Head

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... or more easily, unplug the cold-start valve, and test for continuity between that connector and the one you think is the thermotime switch connector. They should both be wired in parallel, so wire A on the thermotime should connect to wire X on the cold start, and wire B on the thermotime should connect to wire Y on the cold start. If you don't get zero-ohmish readings, then you've probably got the temp sensor plug instead -- or corroded connections! (Note here: I've just been into my harness, and I had corroded connections. ;))

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Sarah,

Thanks for the advise. I tried following the wires, but it's a pretty tight mess and I didn't want to have to cut into a good harness. Testing the wires for continuity just didn't occur to me...I guess that I couldn't see the forrest for the trees.

Thanks again,

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Actually, I haven't gotten to that point yet. I was intending to start her up this evening - after checking for continuity on the thermotime and water temp sensor harness, rebuilding the fan clutch, remounting the fan/fan clutch and radiator fan shroud, and filling/burping the new aluminum radiator. Now I won't have to check the continuity - one less thing to do tonight. Thank you.

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On 9/15/2008 at 9:30 AM, sblake01 said:

Keep us posted. How did you get around the three row pulley problem? Nissan did it by moving the fan on the ZX forward which is not an option on the 280Z.

Doing some late night (early morning) research, and saw this.  I just got done putting a ZX engine with the 3 row pulleys in my 76 Z.  Didn't notice the 3 row pulley and it's clearance problem til it was installed...   I could have tried to remove it by removing the crank etc...  Didn't want to do that.

I ended up making a "spacer" with longer bolts (with a short hex cap) installed from the back, then added 2 nuts from the front, moving the fan about 1" forward.  This cleared the pulley, and didn't touch the radiator.  Yes, it sticks out about 1/2' from the shroud, which isn't ideal, but it works for now.  Made sure everything was tight and lined up good.  Engine has run and does not loosen the connections.  While testing the timing, the strobing of the timing light showed that all the nuts/fan connection line up almost perfectly, so it is balanced.

HTH those who need some improv ideas.  

Also I believe the 3 row pulley is needed for power steering only.  I can get an AC belt on mine now, but it goes on the 2nd pulley.  

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Wow!  A quote from almost 8 years ago.  Back when I was still active and still had my Datsuns. 

  • Like 2

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5 minutes ago, sblake01 said:

Wow!  A quote from almost 8 years ago.  Back when I was still active and still had my Datsuns. 

I wish you were still active, Mr Britannica. LOL

You don't know how much information you've provided for me. Thank you!

  • Like 1

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On 6/7/2016 at 6:47 PM, sblake01 said:

Wow!  A quote from almost 8 years ago.  Back when I was still active and still had my Datsuns. 

Haha I remember when I first got the Z 6 years ago sblake provided me with lots and lots of help!     I never forget those sort of things!     Also, since I assume the internet isn't going anywhere anytime soon, it's worth my time to contribute where I can, so the info will be there for others in the future.  Time sure does fly by though...

It feels good to finally be able to give back some information to help others.

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