JEL

Hello,

I have a nice, recently acquired 2000 LS400 that's in great shape and been well-cared-for all its life at the dealer. It has about 100k currently. Anyway, the auto headlamps have been working fine (as well as the mirrors tilting when going into reverse) up until today. Now today we had to get a new key at the dealer and apparently they did mess with the ECU at some point? I'm not 100% on that one, but as of tonight those two features are no longer working, the DRL still come on, and the lights work fine manually, but it would be nice to have the auto lamp feature for those long road trips and whatnot, and also the fact it's a Lexus of course.

It's a nice smooth car, I went through and replaced all the fluids from stem to stern, diff to coolant and everything in between. Do you guys think disconnecting the battery for 30-40min would do the trick, or would that set off some goofy immobilizer like it did in my Mercedes (two day nightmare to remedy). The "function" key on the wheel also appears to do nothing, I was attempting to use that to see if some things had been disabled but nothing happens when pressed, but I haven't had this thing long enough to know for sure what that key does/did.

Thanks for reading my long post.

Kansas

The mirrors auto tilt only if the mirror switch is in the Left or Right position - not if it is the center. That's the first thing to check.

Is the headlight switch in the AUTO position? Make sure nothing is blocking the sensor on the left side of the dash top.

JEL

Thanks for the reply, that did indeed take care of the tilting mirrors, I guess I missed that in the booklet. The headlamps are still not functioning on auto mode, the switch is definitely in the 'auto' position. This car has the same auto lamps as my '03 IS300, but tons of other electrical gadgets that aren't on that car so I am getting used to all that stuff.

I was thinking about doing the battery pull, this would give me a chance to clean the MAF, but I'm concerned it will immobilie like my Mercedes did.

Lavrishevo

iTrader: (1)

You don't need 30-40 min on our cars to reset the ECM. It only takes about 10-20 seconds. Try it. Just disconnect the negative for 20 seconds and put back on. On the restart you A/C system will blink and do it's thing in self test mode and my VSC system light stays on for about a min. I assume it is also doing a test as well.

Fluid wise, it does not hurt to do everything. Power-steering, trans drain and refill (not flush), differential, etc. You should definitely clean your throttle body. MAF cleaning is really not something that would benefit you unless yours is particularly dirty. In general, the MAF's don't dirty unless something is contaminating it. Just be extra careful when cleaning it with MAF / contact cleaner. Optical AFM's should never be cleaned as duly noted by PD.

With the auto lamp feature, are the lights not tuning on when it is dark? Are they not going through their leveling when the vehicle is turned on? Please be more specific.

Kansas

The function button on the steering wheel only returns the trip computer display to its normal mode after a problem message is displayed. I've had to press it only once or twice in the last nine years to clear a message.

It's possible I suppose that the dealer somehow decreased the sensitivity of the automatic headlights. I've attached the list of all customizable features on the 98-00 LS400. Do the lights turn on automatically if the car is in a totally dark garage?

I would caution against performing non-standard maintenance like cleaning the throttle body and MAF unless there are clear indications there is a need to do so. Just follow the maintenance schedule in the maintenance booklet that came with the car.

JEL

Thanks for all the info so far.

The auto lamps never turn on now, even in pitch dark conditions. Of course everything is still working fine manually, including the fog lights. I think I'll try pulling the battery cable and seeing if that resets everything, I just find this odd to come on all of a sudden.

PureDrifter

iTrader: (10)

If it was an ECU CBET (sp) change then the battery pull won't fix it as those settings are stored in non-volatile RAM. The light sensor CAN go out,though it's relatively rare. Testing it is somewhat simple and involves pulling the sensor out through the top of the dash and ohming it out with a multimeter.