Oil Temp sensor wiring harness issues

SonicVQ · 04-18-2020, 08:34 AM

Quote:

Originally Posted by OilLeaks

**UPDATE**
So I figured out the problem. I swapped the ECU & still got the same high oil temp reading even though I got the proper readings of 5v on the green wire and 0v on the black wire. I decided to do a little more investigation. As it turns out, there was no continuity in the black wire. I replaced that wire and everything started working again. I guess when the previous owner did a repair he didn't do it properly. Apparently, the ECU will default to a high temp reading if the sensor isn't working. I doubt anyone else will have the same problem, but if they do, hope this helps!!

Good news!

However, the reason the ECM showed a high temp, was because of bad wiring.

The engine oil temperature sensor (and the coolant temp sensor) decrease in resistance as warms up, and increases in temperature as it cools. This is known as a negative temperature co-efficient sensor (NTC)

Since the ECM reported a very hot temp, the resistance it saw was very LOW, like a partial short to ground.

When the sensor is cold, the resistance is very high. If the sensor is disconnected, it will show as -40, because with the sensor being removed is a (very) high resistance.

Anyway, I'm glad you got it all sorted out!
Thanks for the update.

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