transmission or heating problems?? help!
 

hi i have a 99 es 300 auto the heat gauge needle is always reading lower than the center even when warmed up sometimes it sits below the first line, when cold it shifts all gears fine except for the fourth gear it wont even shift into until it is warmed up what could be the problem for this? could it be the thermostat causing this? what do i do i am really not wanting to have to get this thing rebuilt as i just bought it, I love this car!

I should add that its -20 were i am at the moment

Thermostat & Coolant Temp Sensor are something i would look into.

Some of the cheaper things you could replace

Hi,

I need someone to provide exact detail, but its for certain that these cars will NOT shift into overdrive (your u140 is 3 speeds plus overdrive for a total of 4) until they are a certain temperature.

http://akpp19.ru/files/toyota/U-140E,U241E.pdf that document talks about a temp sensor for a 4th gear upshift.

Also, your temp guage should always read "48%" ish, that is, just a hair below the 1/2way point. in -20 and 115f, that should be the same. If your thermostat is bad, that wont be the case. If its not bad and you temp sensor is, it will read wrong and confuse the transmission.

If your saying the car shifts totally normal once its been warmed up, that's how its supposed to be

I missed that yours is infact reading low.

just yesterday I pulled P0117 or something on a friend's 2009 camry for a bad temp sensor. My point is, that sohuld cause a check engine light. My 2009 honda Van dropped from center where it sould be to 0 when we kicked the heat on high. Pulled the thermostat and found massive abbrasions from it sticking... new one and problem solved. Not a hard job on you lexus. If it is the sensor, use a DENSO. also, use genuine toyota coolant.

See if your radiator is cool to the touch when its been running a long time and the needle is low. If its not, start with the thermostat.

I think its normal for automatic transmissions to not shift or delay shifting to next gear when the ATF is still cold. It functions at a certain temperature as far as I'm aware. You hardly notice this when the ATF is fresh or new, so I would strongly recommend to check the health of your transmission oil and change it if its dirty. I recently changed mine as the ATF was already black. I didn't have shifting problems, other than a delay in second gear when its still cool, and I always warm my engine before driving it, and after doing one flush I noticed it would shift second gear sooner than before. Before ATF change while engine was still cool, it would wait until 3k RPM before shifting to 2nd gear, after the first flush it shifts around 2500 RPM. I should do the complete flush in a few weeks, I just wanted to see first how the transmission would take one flush since the ATF was already black.

drain and fill a few more times. Don’t flush... that’s hard on an old/worn transmission.

Again, the u140 will NOT go into overdrive when below a certain temperature, weather it’s 1999 and you just bought it new or it’s 2050 and it has 991,428 miles on it. Your temp needle is another issue that needs to be addressed