Vehicle is a 2003 Lexus GX470 with 309000 miles on it. While driving to the mountains it was fine on the highways I used the lower gears to slow myself down a bit as well as using the brakes going down the mountain then proceeded to use transmission normally in drive. Then going up through a town with slight sloping about 8,500 FT elevation car started to have issues or loss of power and although the speed limit was only 25 there it even struggled to do that I decided to turn back around. There was definitely a loss of power or something happening not being transmitted to the wheels. I will add there was no check engine light no oil temperature light no at temp light or any warning light at all. I also pulled over on level ground with the car heated up but the transmission oil dipstick and it was at the level it should be for hot operating temperatures.I was barely able to make it back down from the mountains home but I did. The next day when it was warmer outside and in town I drove it just a few miles and it seemed to drive normally like it had before the issue I even got on the highway and was able to get it up to 80 miles an hour. I didn't go far I just went a few miles and then came back. Anyone have any idea what the issue could be and potential things I should know? Thanks in advance.
Gx470 Drivetrain Issue ? Any help (1 Viewer)
- Thread starter MountainMan1776
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im no expert but could transmision of overheated or is fluid old?
I didn't know it had a tranny dipstick in the '03.
Only year that does.
What was the weather that day? Did you check the air intake and filter?
I think auto transmission had dipstick up to 2003 then 5 speed box sealed for life. I may be a year out as in uk we got new model earlier than usa
- Thread starter
- #6
Thank you for the reply.
There was no A/T Temp light ,the fluid is old but not milky. Has a light brown color so I know it does need to be changed. What's weird is it seemed to drive fine a few days after the issue. Im still wanting to get it checked out to see how much $$$ this will be .
- Thread starter
- #7
The weather was cold and we had gotten snow the night before as well as light-mediun snow during that day I didn't check the intake and filter closely ,Im going to remove the cover and take a look. You think built up snow or ice could have caused the engine to not be getting enough air ? I honestly didn't think of this, so thank you for being it up.
Just checked my records and the engine air filter was replaced in August of 2019.
Change atf anyway its seriously 30min fot first drain ( circa 4liters) to setup drop cloths prepare tools etc. start engine after each fill to mix old and new then drain it again. Do it 3-4 times
After 1fill next will take u i dobt know but max 15mins .. drain fill drain fill
Use original toyota atf type 4 its cheap whole process will cost You less 200$
16quarts atf
Oil change pan
If i remember right drain plug is socket 24mm
Dont forget about new crash washer.
Oil should be red even if worn. Not brown
Btw if you dont know much about condition of the car due to previous owner/s you better change cabin filter.if you didnt do it you might be surprised.. i found tons of tree nuts...🐿
After 1fill next will take u i dobt know but max 15mins .. drain fill drain fill
Use original toyota atf type 4 its cheap whole process will cost You less 200$
16quarts atf
Oil change pan
If i remember right drain plug is socket 24mm
Dont forget about new crash washer.
Oil should be red even if worn. Not brown
Btw if you dont know much about condition of the car due to previous owner/s you better change cabin filter.if you didnt do it you might be surprised.. i found tons of tree nuts...🐿
When was the last time you bought fuel before it happened, then after ?
- Thread starter
- #10
I haven't put any fuel in it since the issue occurred. It doesn't get driven much ,especially now. Couldn't say when it was filled before that maybe 2-3 weeks prior was last fill up.
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- Thread starter
- #11
great thank you so much for the info. I am aware the atf is suppose to be red and have been meaning to get to it. This this issue that occurred I will expediting that now , but question is should I replace the metal filter/screen in the transmission while I'm in there seeing as the gx470 is @ 309k miles. I would hate to start the process and end up needing a new transmission because I ended up clogging the filter in the transmission .Just trying to figure out what the best option is. Cabin air filter was also replaced in august 2019 along with engine air filter.Change atf anyway its seriously 30min fot first drain ( circa 4liters) to setup drop cloths prepare tools etc. start engine after each fill to mix old and new then drain it again. Do it 3-4 times
After 1fill next will take u i dobt know but max 15mins .. drain fill drain fill
Use original toyota atf type 4 its cheap whole process will cost You less 200$
16quarts atf
Oil change pan
If i remember right drain plug is socket 24mm
Dont forget about new crash washer.
Oil should be red even if worn. Not brown
Btw if you dont know much about condition of the car due to previous owner/s you better change cabin filter.if you didnt do it you might be surprised.. i found tons of tree nuts...🐿
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Anyone else concerned about changing ATF, for presumably the first time, at 300,000+ miles? There may not be an alternative, but I've always been advised to "just leave it alone with that many miles......."
Does the 2003 have SAIS? I thought it was 05+
Limp mode usually throws lights or codes (do you have any codes?) but then it could be this gem:
@Vlad might have some thoughts as he's well-versed in his 03...
Limp mode usually throws lights or codes (do you have any codes?) but then it could be this gem:
@Vlad might have some thoughts as he's well-versed in his 03...
- Thread starter
- #15
No CEL but I did scan for pending codes which showed one code
P0430 - Catalyst System Efficiency Below Threshold Bank 2
P0430 - Catalyst System Efficiency Below Threshold Bank 2
P430 shouldn't be the cause. P430 is either your O2 sensor or an exhaust leak on passenger side. P420 is driver's side.
Good point and easily checked with a vacuum gauge. Your symptoms actually mimic an exhaust restriction and with the amount of miles on the truck, this isn’t out of the question.
There is no limp mode, no SAIS in an 03. It is more basic (and I love it). Sounds to me like you had a viscous failure of the fluid from heat. If it is not bright red it is likely burnt and slipping with engine braking down hill then losing power up hill. You can't engine brake without heating up the ATF unless you have a manual torque lock up (which I do). I wager you can swap ATF and go on your merry way.
- Thread starter
- #20
This is what a local shop thought could be the issue as well. I hear that the manifold /catalytic convertor are together and can be a PITA to remove/install. I think ill be doing a drain and fill on the ATF as it needed it anyways.Any advice on that with 309k ,should the metal screen filter be replaced. Im going to have to drop the pan as the gasket was leaking. Im also somewhat considering the idea of selling and getting into a newer gx like a gx460 but haven't looked into those much yet. Really appreciate all the help everyone has given.
