speedy1234

Hi everybody, I just bought this used 2000 rx300 from an auction through a dealer friend of mine with 109k miles on it, after like 10 miles the check engin light came on. I checked the fuse box and noticed AF heater fuse missing, so I replaced it,. That took care of the check engin light after i reset the ecm, but now the transmission is acting realy crazy. My first hunch was the throttle position sensor and engin temp sensor so i had them replaced as well, but no luck> Can anybody help.-Thanks

Lexmex

Oh, the tranny does give fits after that. When I do exhaust mods, pull the batter cables off or pulling the EFI fuse, the ECM does not like that and the tranny will act up for a bit. Basically, non-responsive when you hit the gas. Give it a bit.

I am surprised it is not throwing another light.

Let me know.

speedy1234

Thanks for the info. I have reset the ecm. Weird thing is the tranny works fine without the Af fuse, but then the ecm light comes on.

Lexmex

Well, what the ECM is probably doing there is going to a default mode so that the vehicle could still run (as in being able to pull off the road in case the fuse dies).

speedy1234

Question is why is it that I do not get any codes when the af fuse is connected and how come the tranny acts up in that condition. Obviously there is some kind of miscommunication between the ecu and tranny.

Lexmex

At that point after you put in the new fuse, the ECU does not have enough information on the air/fuel from your driving habits. It is more or less in a default mode for a moment and then as it gets more information it will be more stable.

I can tell you with my exhaust modifications over the years, sometimes that means 1 week of driving to the office and back. That is not the case with a stock system and usually after a day or so it shoud be fully functioning.

The RX300 sports an adaptive transmission that goes hand in hand with your driving habits. Basically, if you drive it up 1/4 mile tracks all the time, it will get comfortable with that. If you do city driving, it will do that. Either way, you either gain or lose MPG through those driving habits.

The light comes on when something is out of its paremeters, particularly emissions and will throw a light.

The other thing to do, to really clear out the system is to pull off both (I found out just pulling the negative is not enough) battery cables off for about 30 minutes (you will have to reset seat settings, radio presets, the clock), but it is more effective in my view that pulling the EFI fuse for a moment.

When I pull the EFI fuse at the track, my first two runs are pure crap, and then things slowly, but not absolutely, kick into gear.