Softail Deluxe Temperature sensor? - Harley Davidson Forums: Harley Davidson Motorcycle Forum
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post #1 of 2 (permalink) Old 11-21-2012, 11:41 PM Thread Starter
Proud South African
Join Date: Jul 2012
Location: Centurion, South Africa
Posts: 52
Softail Deluxe Temperature sensor?

I did an interesting thing to my speedominator... I added a line that reads and decodes the diagnostic data transmitted by the ECU. One of the things I obtained this way was the engine temperature. I compared this temperature to the one I measure from the cylinder head (my sensor is like a washer that sits between the sparkplug and the head).

I notice that the ECU reports the temperature about 18F colder than what my sensor measures. And that is while the engine is still cold. After riding to work my sensor measured 300F while the ECU said 233F.

Now I rather trust the ECU's temperature, but I'm wondering why the big difference. Just to validate the accuracy of my temperature sensor I connected another one, and it read the same. So, I know I am measuring the CHT correctly.

The question now... where does the ECU measure the temperature from? And, does it measure oil temperature? Or Cylinder temperature? It's a 2006 Softail Deluxe.
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post #2 of 2 (permalink) Old 11-22-2012, 05:57 AM
Retired citizen
Join Date: Jun 2009
Location: Pt. Wash.,WI
Posts: 17,233
The oem temp sensor measures the actual front head temp. Remove it for inspection and you'll see. It screws into a dead end hole, it doesn't protrude into the combustion chamber. It's located behind the horn in the front head, pull the rubber boot back, unplug the electrical connector and screw it out. I think the temp sensor is a thermister.

Disclaimer : Don't believe anything I say unless you are absolutely sure that I know what I'm talking about .
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