04 Scion XA, blue light on dash on ?

[Lager]

Ok ,highly knowledgeable Toyota guys ? Ive got a question.
There is a blue light that comes on my dash panel and will not go off until the engine reaches a certain temperature. Until that time, the transmission will not shift into 4th gear and its been like this every since I bought the car brand new in 2004..Back then the light would go off quite quickly, but now ? 15 years later and 394,000 miles later its taking longer and longer to turn off.When its cold now,, it will take about 15 minutes of idle before I can even leave the driveway.. What is the logic that concerns that light? I thought that maybe the thermostat was staying open a bit, making the engine take to long to get to temp. But checking the radiator hoses with my infrared temp sensor shows that not the case. Is logic program tied into the O2 sensors and decided when it goes into closed loop ?
Im a very long time mechanic, 40 years now at dealership level with Honda. I cant find any information on what the PCM's logic on the blue light and its control over the transmission. Any ideas??

 

[Majicmike]

I have a 15 XB and my warm up light is orange,, that's all I got

 

[Mike Overlay]

If memory serves me right. Staying out of 4 gear is to get the engine up to operating remp quicker.

Older Toyota versions, early 90's were monitored thru coolant temp sensor for the ECM.

Scan tool data should be able to see the temp data even in generic OBD2 info.

 

[Short Fuse]

What Mike said plus your owners manual will probably explain the light.

 

[FarpinDar]

If it is a warm up light it sounds like your thermostat is stuck open.

 

[Lager]

If memory serves me right. Staying out of 4 gear is to get the engine up to operating remp quicker.

Older Toyota versions, early 90's were monitored thru coolant temp sensor for the ECM.

Scan tool data should be able to see the temp data even in generic OBD2 info.

Yep, exactly right.. But, it wasn't like that when it was new.. Now , even when its 90 degrees outside, it takes quite a while before it will shift to high gear.. I hade the chance tonight to use the scanner on it,, it when into closed loop at about 100 ECT, but the blue light was still on so its not controlled by that..It wasn't until it hit 140 on the ECT and that's when the blue light went off.. Im going to beat some more bushes out there, but you are correct..

 

[Lager]

If it is a warm up light it sounds like your thermostat is stuck open.

yeah, that's what I was figuring?? But the hand held temp gauge clearly showed that the thermostat wasn't allowing any coolant to get passed and sent thru the radiator prematurely.. Still sitting here scratching me old bald head over this one..Thanks for your reply, you are correct in your suggestion.. Thinking I just might throw one in there anyways ?? At this mileage, nothing lasts forever..

 

[NCLivingBrit]

It lets you know when the hamster needs a new belt on it's wheel

 

[Lager]

Im really hating to have to go to a Toyota Forum and start asking questions there.. Like all car Forums,, every one is an expert and just because their cousin saw it on the internet somewhere ? It HAS to be true...Even tech only forums can be mis leading, seems like everyone there pounds their chest and claims they know everything... I might have to visit my local Toyota dealer and sneak into the back door and find a kindly master tech.

 

[Lager]

It lets you know when the hamster needs a new belt on it's wheel

You Think that's Funny ???? LOL yeah it was funny ….Its gets down the road pretty good for its 60 HP that It has left in it... Whats even more funny, I work for Dodge,, the starter motor has more HP that fires up the Demon, then what this engine produces..Well,,, not really, but you know what I mean..

 

[NCLivingBrit]

You Think that's Funny ???? LOL yeah it was funny ….Its gets down the road pretty good for its 60 HP that It has left in it... Whats even more funny, I work for Dodge,, the starter motor has more HP that fires up the Demon, then what this engine produces..Well,,, not really, but you know what I mean..

What's funny is I drive a tylenol on wheels even more sedate than the Scion, the Mazda 5

 

[noway2]

394,000 miles? Hmm. My commute vehicle is an xD with going on 283,000.

Thermostats are generally cheap and easy to change. They’ve been the go to for slow to warm up cars for decades. Might be worth trying.

 

[Mike Overlay]

NAPA part number TS5601, coolant temp sensor.

Wiring diagram shows that the yellow wire from the sensor is the side that does the Cold warm up info to the dash indicator and the ECM. Yellow/red tracer does the Hot indicator on the dash.

Then the last wire is used for Radiator fan control.

 

[Lager]

View attachment 100742

View attachment 100743

NAPA part number TS5601, coolant temp sensor.

Wiring diagram shows that the yellow wire from the sensor is the side that does the Cold warm up info to the dash indicator and the ECM. Yellow/red tracer does the Hot indicator on the dash.

Then the last wire is used for Radiator fan control.

Thanks for the info Mike,, I thought you were onto something when I saw the 60 degree cel. Then did a conversion into F and its right at the 140 degree F when my light goes off and the trans is allowed to shift.. Im starting to think, " It is what it is" or just throw a throw a themo in it and call it a day..