aaddpp

So I hooked up a Scan Gauge II to measure the ATF temp in my 2009 ES 350. After going through the programming motions I was able to get the unit to show ATF temp, but the reading is bouncing around all over the place..from 17F to 82F to 23F etc. etc. etc. I'm wondering whats causing the jumpy readings: bad ATF sensor? fluid level? bad scan tool? Should note, that I did an ATF service - flushed fluid with new Toyota brand WS, and measured temp / set level using the pin jumper method, and the "D" light. Post service, the car runs smother, but I feel a few subtle slips, and clunks in the trans that weren't there before. The reading from the scan tool is making me question the temp when the "D" was illuminated. What do you guys think?

ESh

Bad scan tool

aaddpp

Yeah, I'm thinking that it could be. What's making me think twice about the scan tool though is that other "gauges" the tool is showing - like the coolant temp - are steady, and rise / fall as you would expect. I'll probably order another scan tool, and test it to see - probably the easiest question mark to eliminate.

Thanks - Dave

aaddpp

Might not be the scan gauge after all. I just hooked up a KOBRA WiFi OBD reader, and using the OBD Fusion App, got similar jumpy readings - see screen shot below. Might try an IR thermometer and see what it yields.

Anyone ever have a bad ATF sensor? How much of a deal to change? Log below shows two sensors, but I doubt that two sensors could fail at the same time..so I'm thinking something else is going on here...

One last observation. Being in P or N vs R or D makes a difference in making the gauge go nuts. Tends to be more steady in D/R, but reading seems to low in general.

Thanks - Dave

jagtoes

Most likely there is no damper in the system and you are getting raw data. Same with water temp and voltage , etc. Depending on what you select on the scan gauge to read you will get some variation . Things like voltage (CM) controlled mode and Voltage (AD) adjusted . One reads variation and one reads steady.

aaddpp

For sure its the sensor in the car. I hooked the scan gauge up to my wife's 2014 Camry tonight (same-ish engine), and it worked perfectly...though I ran through every freaking ATF code on the sheet before I found the right one. In the end, I poured about half a quart in the ES350 trans, and then measured with an IR thermometer. The pan is not evenly heated, so I waited until I got readings above 104 but below 110 in various spots around the bottom of the pan, and then pulled the drain plug. Car seems ok after a short test drive this evening.

Strange the sensor is not throwing a code in the OBD...but I think thats probably a good thing after reading about changing this particular sensor.

Oh-well, good enough, I hope...

igzy

It is possibly the sensor, but I would also confirm the wiring at the connector. In the last year, I've had to repair 3 connectors (ig coil, camshaft sensor, engine temp sensor) in the engine bay because the wire going into the connector was either broken or intermittent...

aaddpp

Thanks, didn't think about the sensor connector, but that could make a lot of sense. I wonder where this sensor hooks up? Probably buried under the ATF pan somewhere...just to make things easy.

igzy

The connector to AT ECU is on the top of the transmission case, under the intake. The sensor itself is inside the oil pan under the strainer. When the flush was done, was the pan removed and strainer replaced/cleaned as well? It is right behind the strainer, so it could have been affected by any work inside.

aaddpp

Thanks! I'll see if I can have a look at the connector. As far as the pan goes, I didn't open / remove it...it was just a flush of the old fluid, so none of the internals were messed with.

Thanks - Dave

gemigniani

I verify the transmission fluid temp is in the specified 104-113 degree range the old fashion way: directly with thermometer (let some fluid drip into a styrofoam plate or cup and immediately insert the thermometer probe into the fluid)