Raino

After successfully changing my water pump, timing belt, distributor caps, rotor, etc. I found out that I now have (what would, on the surface, appear to be....) the completely unrelated problem with my transmission:

When engaged in:

Park - car goes in gear, but parking pawl holds the car

Reverse - car goes in forward gear, then reverse engages, locking it up.

Neutral - car goes into low range, but coasts when you let off the gas, as opposed to giving engine braking while in "L"

Drive - works perfectly

Second - works perfectly

Low - works perfectly


Discussion:

After buttoning the engine up when I was done with the water pump job (orginal pump, 180k miles) I started up the engine, which fired right up, no leaks, noises or anything unusual. I let it warm up while I was checking for leaks, etc. then got in the car and proceeded to back up. When I put the car in gear, and it didn't go, I have worked on cars enough to know when the AT is low on fluid. I did lose some ATF from the ATF cooler lines when I removed the radiator as part of the water pump job. No problem, I just went to my convenient Lexus dealer and bought the right stuff (T-IV, which replaces T-2, not to be confused with Dexron -2). Anyway, that is when I noticed the problems I am describing.

I have the factory service manuals, but the transmission troubleshooting matrix does not cover my problems. I talked to my Lexus dealers in the area, and none of them have EVER had to do any repairs on ANY LS 400 transmission, even ones that were driven with low fluid levels for relatively long periods of time, so I am ruliing out any catastrophic damage at this point.

I checked the linkage, and it is fine, and adjusted properly.

Because the car behaves perfectly in "Drive" "S" and "L", I don't see how it could be any locked up clutches or bands, and because reverse does seem to engage and disengage (a split second after the car starts to creep forward when putting the car in reverse). Anyway, I am fairly convinced there is no catastrophic damage.

What seems more likely to me is that somehow one of the valves that controls the low range is sticking, and probably the one that works the low range while in "D" mode. If it were always locked into low, though, it would probably lock the transmission when it tried to shift into second or third.

I haven't looked at the valve body schematics in detail yet because I was hoping it was something silly or very easy to fix that someone has had happen to them before, or just knows the LS 400 Transmission internals very well.

I would appreciate any help.

Thanks,