Mn06gs300

I bought a used 2006 gs300 awd, I noticed that when driving occasionally it takes awhile to shift up to 6th gear both in the automatic and the sport mode. It’s not every time and it’s only when I’m just trying to cruise. So I’m wondering what the problem is and how I would fix it

ibidu1

iTrader: (1)

Common issue is for 2006 GS300 (only that year) to have ecu issues for the transmission. Thankfully SIA electronics are able to test and repair the ecu for a pretty good price. Many members have used them with positive results. Its also possible the transmission fluid needs to be replaced. But I would do the ecu first.

https://siaelec.com/product/15410/

ibidu1

iTrader: (1)

Another issue with these 2006's sometimes solenoid goes bad, but majority its the ecu

Mn06gs300

I do actually need to change the transmission fluid soon, so if I change it and it still is a problem I’ll look into fixing ecu.
thank you

ibidu1

iTrader: (1)

I would only do a drain and fill, open the transmission drain pour it into a measuring cup. Replace with new toyota wts fluid, but add just a touch extra to compensate for the loss, but do not overfill. Do this 2 times with 3,000 miles in between then a 3rd drop the transmission pan and replace the transmission filter with oem.

The dealership or even toyota dealerships can do this. Just ask for drain and fill