75 280Z Water Temp Sensors Wiring - Nissan : Datsun ZCar forum :Nissan Z Forum: 240Z to 370Z
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post #1 of 8 (permalink) Old 07-24-2019, 07:49 PM Thread Starter
CWL
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75 280Z Water Temp Sensors Wiring

I have searched the forum but haven't found the information I am hoping to find. Maybe I missed it.

Can someone please direct me to a comprehensible source detailing the wiring for the 280Z water temp sensors as depicted in the image below.

Although I have owned my 75 280Z for 20 years, it has been in storage for the past ten years. Before storage, the car quickly developed issues of running lean and smoking. Work was started but stopped suddenly, and memory faded. Now I am resuming the work, and I want to check all of the water sensors, wiring, and related components. Currently, it is dumping too much fuel in the injectors. Injectors are good, and fuel pressure is good. Any guidance would be appreciated.






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post #2 of 8 (permalink) Old 07-24-2019, 10:54 PM
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download the '75 factory service manual (FSM) to get all the wiring diagrams and troubleshooting procedures for your car. you can get it here:
www.xenonzcar.com

Bon

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post #3 of 8 (permalink) Old 07-24-2019, 11:30 PM
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Check the thermotime switch for proper operation, and the connectors to it. If it is not working, the cold start valve stays on longer than it should, causing a very rich mixture.

Larry


1976 280Z - Street

1973 240Z - SCCA Autocross F Prepared
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post #4 of 8 (permalink) Old 07-24-2019, 11:33 PM
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Originally Posted by CWL View Post
I have searched the forum but haven't found the information I am hoping to find. Maybe I missed it.

Can someone please direct me to a comprehensible source detailing the wiring for the 280Z water temp sensors as depicted in the image below.

Although I have owned my 75 280Z for 20 years, it has been in storage for the past ten years. Before storage, the car quickly developed issues of running lean and smoking. Work was started but stopped suddenly, and memory faded. Now I am resuming the work, and I want to check all of the water sensors, wiring, and related components. Currently, it is dumping too much fuel in the injectors. Injectors are good, and fuel pressure is good. Any guidance would be appreciated.





There are a variety of reasons for the car to run rich. Right out of the gate, check all of your connectors for corrosion - these cars run like utter ass with poor conductivity. Break out the sandpaper and hit all the spots shown here: http://www.atlanticz.ca/zclub/techti...ons/index.html

You will most likely find that one (or more) of those sensors/their connectors are corroded - causing the problem. My car was running very rich and it ended up being a dying AFM.

1978 280z - stock L28 engine - Dallas, TX
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post #5 of 8 (permalink) Old 07-30-2019, 02:55 PM Thread Starter
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I downloaded the FSM - Great source! Thank you Bonfire79.

Also, thank you Crayzlair and Chaseincats for the information you have provided.

I need some clarification concerning the wiring and connections, and I am not getting it from the FSM. I am a newbie in some regards. I will check and replace the sensors after I understand the wiring and connections. I am unclear as to the wire ends that are circled in yellow, orange, and red in the picture below. Any input would be appreciated. I am in a rural area, so I don't have easy access to take a look under the hood of a nearby Z.
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File Type: png Wiring for senors -.png (614.2 KB, 14 views)

75 280Z
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post #6 of 8 (permalink) Old 07-31-2019, 11:47 AM
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I downloaded the FSM - Great source! Thank you Bonfire79.

Also, thank you Crayzlair and Chaseincats for the information you have provided.

I need some clarification concerning the wiring and connections, and I am not getting it from the FSM. I am a newbie in some regards. I will check and replace the sensors after I understand the wiring and connections. I am unclear as to the wire ends that are circled in yellow, orange, and red in the picture below. Any input would be appreciated. I am in a rural area, so I don't have easy access to take a look under the hood of a nearby Z.
I don't understand your question. This are the bullet connectors for the water temp sensors i believe. Break out some sandpaper and sand down the male ends then pull the connectors in/out/twist in the female to clean the female connector.

That said, they don't look especially corroded...

1978 280z - stock L28 engine - Dallas, TX
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post #7 of 8 (permalink) Old 07-31-2019, 12:00 PM
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The red and blue wires connect.
The black wire and the white wire are for the vacuum switch solenoid (Federal models).
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File Type: png Wiring for Temp Sensors and Switches.png (288.7 KB, 10 views)


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post #8 of 8 (permalink) Old 08-02-2019, 05:08 PM Thread Starter
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Steve240Z73 - Thank you for the wiring information. I will double check this soon.

As for now, I have cleaned connections and the car is starting and running. The connection to the cold start valve was apparently an issue that was preventing the car from starting. Also, cleaning a sensor connection revived the temp gauage.

When in nuetral, the car idles proper; however, when in park, it idles around 1800 rpm. I am thinking vaccum leak and will start checking for leaks to possibly correct the high idle when in park.

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