Figuring out calibration values for oil temp sensor / sender (MS3/MSPnPPro)
 

EDIT: added the resistance readings I took to the end of this post if you happen to have the same temp sensor. Scroll down.

Adding for search/SEO: temperature sender / temp sensor I'm working with is the VEI Systems SEN-T320D "Oil, water/coolant, or transmission temperature sensor"

Hey y'all,

Sorry for what is probably a newb electrical question, but I'm wondering how to calibrate my MSPnPPro with some new sensors I picked up. One of them has specs for voltage ranges and corresponding sensor readings, but the other one (fluid temp sender) does not. What's the best way to figure out calibration settings for this temp sender?

My best idea so far is to hook it up to a multimeter and put it in water at three known temperatures and just use those values in calibration, but I figure there might be a better way.

Some extra details just in case it helps:

• I bought this temp sender: Oil, Water/Coolant, Transmission-Fluid Temperature Sensor - VEI Systems
• I have an MSPnP3 / MSPnP Pro for a '93 1.6 miata.

Thanks in advance!

Update: If you happen to have the same sensor, here are the values I came up with. USE AT YOUR OWN RISK. Values may be incorrect as a result of poor equipment or poor methodology. I dunked the sensor in ice water, boiling water, and ambient temp water and waited for resistance readings to normalize. I also took the temp of the water for each.

• 32F (ice water): 5,680 ohms
• 66.9F: 2,310 ohms
• 211F (boiling): 103.1 ohms

Do you have a multimeter?

Measure the resistance across the sensor under the following three conditions:

1: At room temperature
2: Immersed in a glass of ice water. (The sensor should be near the bottom of the glass, and not in physical contact with the ice.)
3: Immersed in a pan of boiling water (The sensor must not be touching the bottom of the pan.)

Cool, thanks Joe. Sounds like I was mostly on-track.

One other newb electrical question for anybody seeing this...how does this sensor work with only one wire? When I'm trying to get a reading from the multimeter, am I just assuming that I'm grounding off of the threads of the sensor or something?

Yup. Pretty common for temperature sensors (both OEM and aftermarket) to be grounded through the housing. This is why you can't mount one in a remote-thermostat housing, for instance, without running a ground wire to it.

Makes testing annoying unless you have hippo-clips or similar. I do not recommend using your fingers to hold the ground wire to the body of the sensor while it is immersed in boiling water, unless you are an arm amputee and use a hook-type prosthetic.

Awesome, thanks for the help! I also added an update to my original post for anybody hunting for these values down the line.