Thoughts on how to wire up a TEMP warning light?

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mtmtntop
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Joined: Sun Dec 28, 2008 10:41 am
My tercel:: 85 4wd wagon

Re: Thoughts on how to wire up a TEMP warning light?

Post by mtmtntop » Sat Apr 28, 2018 4:18 pm

these are great ideas. i'm looking into one of those digital sensors. But... what happens when you experience this.. on vacation, middle of nowhere, car starts overheating. You stop and figure out its probably the fan. I usually have a bunch of spare things with me. I had enough wire to hotwire that fan directly to the battery , and presto, continue on vacation. You do have to disconnect it at the battery when you stop, and connect it to go on your way. So what i have on all my cars now are 2 wires spliced into the fan wires that are long enough to reach the battery + and - negative terminals. If the switch goes out, you are still mobile with minimal energy. Just tuck those wires away (ends taped of course) near the radiator bottle and you are good to go.

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rer233
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My tercel:: Multiple

Re: Thoughts on how to wire up a TEMP warning light?

Post by rer233 » Sat Apr 28, 2018 7:18 pm

Our cars are real easy- if you want the cooling fan to run whenever the ignition is on, all you gotta do is pull the plug off the temp switch in the bottom of the radiator. God I LOVE simple!
if it aint there, there's a good chance it won't break!
83 SR5 Silver/Blue (Snowmobile/work beater)-totaled but drivable
85 SR5 Blue
88 SR5 White (the 'good' one)-not anymore-totaled
87 fwd silver wagon a/t
87 4wd dx Cream (a/t- not anymore- now m/t)

tercle
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My tercel:: 1985 SR5
Location: Seattle

Re: Thoughts on how to wire up a TEMP warning light?

Post by tercle » Sun Apr 29, 2018 9:18 am

tercle wrote:
Sat Apr 28, 2018 11:22 am
This is a Comparator Module that I bought on ebay.
It is available from many sources, with a few types of connectors.
I got this one with terminal blocks (which barely accept 18ga wire).
The circuit board should say DT-110.

I already had a wiring harness hooked up for the one I made, and I connected this module up and tested it on my car.
note: if you are connecting a LED between the white wire and ground, add a current-limiting resistor.

It works if you hook it up this way:

Image

I have ordered a different type of module that is smaller, and I will test that when it arrives.
When I said the pcb should say DT-110, I meant that the DT-110 type was the only one I tested.
There are other comparator modules that will work, but you have to figure out how to hook them up.
These modules are used in robotics and with microcontrollers like Arduino, but some descriptions also say they are for modifying automotive electronics.

Negatives:
There is a strong likelihood that some components are counterfeit, but they work.
The directions are inscrutable. (see below)

1. Enter a voltage and the reference voltage contrast on the module (The reference voltage can be set by an adjustable electrical overcast), When the input voltage is greater than the reference voltage, Relay closed. When the input voltage is less than the reference voltage, Relay does not operate
2. Respectively inputted two special Compare Voltage signal 10 and 12, When the voltage signal 12 is greater than voltage signal 10, Relay closed. When the voltage signal 12 is less than voltage signal 10, Relay does not operate
3. Enter a voltage and the reference voltage contrast on the module (The reference voltage can be set by an adjustable electrical overcast),When the input voltage is less than the reference voltage, Relay closed. When the input voltage is greater than the reference voltage, Relay does not operate (opposite with function 1)
The reference voltage: The reference voltage of the module is the input voltage obtained through precision resistor divider, It determines the range of input voltage reference voltage, For example, the input voltage is 12V, then the reference voltage can be set in the range of 0-12V.

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