Hey everyone, I have a 2006 Ls 430 with about 170,000k miles on it. I plan to fix it up over time. The only real issue is the transmission which i plan to replace soon, but the thing is i previously had a radiator issue which was causing the coolant in my car to leak. I brought it to my guy and he replaced it, but then for some reason the transmission was acting as if it was fixed. My rpms weren’t skyrocketing and it was shifting gears smoothly. After about a week the warning indicator randomly turned back on again and the transmission went back to how it was before. I really just want to know how the transmission was just randomly and temporarily fixed? Anyone have an idea?

 

Yup, that is a very common issue with the 2001-2006 LS430 (and probably other model years too).

That is caused by the ECM (engine computer) that gets intermittent. Since the transmission is controlled by solenoids, those solenoids in turn are controlled by the ECM and when the ECM gets erratic, the solenoids do the same, making it feel like the transmission is falling apart and sometimes even banging when put in reverse. The ECM controls both, the engine and the automatic transmission.

When the transmission is damaged, the problem will stay and it will not feel like the problem is gone suddenly and then come back to the problem.

The thing is that if you continue using the vehicle like this, the transmission will be damaged too if it has not already.

I can tell because I have been in the business of fixing those ECMs since 2008. I won't give the business information to avoid spamming this forum. Instead, you may look in Google or other search engines for shops offering the repair service for your specific ECM.

I hope this helps.

Richard

 

Hello Richard, thank you for responding! I'm sort of a novice when it comes to mechanics but I'm trying to learn as much as I can. I bought the car around the start of January and then a month later, I located the issue with the coolant and then the transmission started "working." That lasted about a week and since then I've been trying to drive the car as little as possible but sometimes it's inevitable for work, school, etc. My rpms go up to 5000 when going 70-80 mph and when I shift into drive/reverse from park, I have to wait a bit until I feel the shift. I also hear a grinding when I let go of the brake and start moving after I shift from park. If I've used the car for most of the day, the shifts from park are smoother and faster but the acceleration is still off. Idk if you can tell from this information whether or not the transmission is damaged but I'm assuming it is. I'm guessing this means I have to replace the ECM and the transmission. I appreciate the response it was very helpful

 

jmend350:

What I said about the ECM still stands, but now that I know more about the case,

#1 The grinding noise is the fact that worries me about the health of the transmission.

#2 Going to 5000 RPMs at 70-80 MPH might be that it is not shifting to the 4th gear.

#3 Waiting a bit until you feel the shift could be low fluid pressure. That happens many times when the filter is clogged or it has an issue with the torque converter.

I have seen clogged transmissions that when it is critical, the car shifts well until it does not. Then you put it off for some time and when you start the engine again, all the sediments already went off the filter and all will work until it is clogged again. The period of working/not working varies depending on how critical the situation is.

The oil pan of the transmission has a magnet, but if the filter is clogged, it means that the magnet is already saturated with debris.

When the ECM is the problem, it is intermittent but when it works, it usually lasts the day. No grinding noise.

Again, the grinding noise is a bad indicator.

All this is theoretical until a good diagnosis is made by an expert in a transmission shop.