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Well, after much deliberation I finally broke down and took the Z to Darrell's Datsuns in San Jose. I had done all the FSM tests and just wasn't convinced it was one particular part. I suppose I'd rather have a second opinion than buy an expensive part I don't need! As I thought the AFM was bad at certain spots, which he confirmed. He also was not impressed with the fuel pump so we replaced both. The NEW AFM was hard to swallow, but whatever it needs I guess. He also replaced the plugs and adjusted the valves. So now it will pass smog and drives fine....but it all comes at a price. Curious thing now though...before all this the temp gauge hovered a little below half. Now it barely gets past the T into the normal range. Its either running way cooler or the sender/gauge are off. Any ideas? He put in non-resistor plugs, but I don't know if they are a diff. heat range than the ones removed. Will heat range affect engine coolant temp? I don't think so.

Kevin
 

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The "Thermal Transmitter" is connected to the Temperature Gauge in the Dash. It has a single "male" bullet connector built into the end of the sensor.

To test the circuit in the car wiring, disconnect the wire at the sending unit (it is at the 10:00 position looking at the front of the motor in a 79 280 n/a) and ground it. The dash meter should go all the way to "Hot".

With the bullet connector completely disconnected the gauge should read "Cold".

To test the "Thermal Transmitter" hook an ohm meter between the terminal on the transmitter and battery ground and start the engine.

You should see the following:

23 C = 400 ohms
25 C = 386 - 365 ohms
30 C = 302 - 290
35 C = 238 - 228
40 C = 190 - 183
45 C = 153 - 149
50 C = 123 - 118
55 C = 98 - 95
60 C = 84.1 - 80.3
65 C = 69.0 - 67.2
70 C = 56.5 - 56.0

So as the temperature increases the resistance decreases and you can use the above to test the functionality of your sending unit.

Wayne Monteath
Masham, Quebec.
 

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Hi.
Good Post 79-280-ZX.
 
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