Update: Diag code 25 91 LS400

That was me....unless you have been spraying silicon under the hood (or had the car detailed)...the O2 sensors lasts forever.

The single most profitable job on a Lexus (using mitchel man hours) is the O2 sensor....so (for the dealer) it is always the problem.

I have "fixed" several trac light problems (I offer to do it for 50% of dealer cost....but always give in for a $20) in less than 10 minutes ---6

10mm bolts and a bottle of dot 4.

If you want to really do prevent:

1). the Dot3 brake fluid was not made for abs and traction...it needs to be flushed often (every 2-3 years). (DOT4 is good but not 5 or 5.1) 2). the "red" antifreeze is 5 year stuff (you can now find it everywhere since Chrysler and GM calls for it) replace it and dump a can of water pump lube into the screw above the thermostat and water pump. This is an item that tend to go at >100k if not looked after. 3). the O-ring on the hose to the steering rack tends to go. It is located above the alternator....the main problem is that the leak kills the alternator and the pump is so quiet that it can run the rack dry without noise. Many have replaced the rack only to have it also go bad because of the leaking O-ring. Note: it is a pain to get to, but is a standard O-ring. The alternator is a very nice denso which is used on the very big John Deer's (cheap parts). 4). If you like to be OCB, the ford size ph8a oil filter fits. So a mobile1 which is syntetic fiber like the denso (lexus) not paper (toyota) and is 3X the size.

It is the best toyota ever built...

cheers,

rd

Hi, nospam, I am apparently missing something here. Can you please explain the above in detail. I am have a trac light "on" problem right now. Been driving it though without noticible fault.

If the Trac light is on (comes on after driving) without a check engine light.

1). Can be caused by a number of faults (which you can blink out on the dash). None of which has anything to do with O2 sensors (yet the dealer tends to claim it does). 2). The most common trac-light fault is a code 19 -- pump has run more than expected. 3). Regardless ... the trac unit is automatically switched off on any fault (not a good thing if you deal with snow or wet). 4). DOT3 and DOT4 are only different in their boiling point ... DOT5 is very different ...DOT5.1 is very thin. 5). When the fluid absorbs moisture (normal over time) the boiling point drops. The Trac pump is strong enough to cause boiling in very "wet" fluid. So on startup when it tries to bring the system up to pressure it gets some steam (stops -- thinking pressure has been reached) then the steam dissipates and the pressure drops....you end up with more than expected pump cycles. The actual traction function is also adversely effected. 6). There is a bleed screw on the traction actuator...using a hose and the car idling (so the pump will run) you can flush the ABS and Trac unit in just a few minutes. 7). Normally (and by a good mechanic) the brake lines are flushed during brake pad replacement, but that is not enough fluid to clear the abs and trac unit. (On a '90 ls400 the trac unit and the abs unit are the size of a toaster -- each ---with a separate trac pump as well) later models like the gs400 have a smaller combined unit). 8). The manual does call for the fluid to be replaced every 3 years, but it does not really spell out the need to flush the abs and trac units (it is assumed that it will occur during the bleed process) hence the issue.

Hope this helps,

rd

Hi, nospam/rd, your explanation regarding this issue is the best I have read, ever. As you know of, the trac light problem almost universally affecting every early LS400. I don't know how many LS400 out there suffer from this and its consequence-- dealership/ wrong diagnosis/ useless spending on expensive parts, and it's the reason I have been continuing to observe the light/ looking for something making sense.

I am a weekend DIYer, or always trying to be. If you can, please illustrate a little more on the procedures to bleed through "bleed screw on the traction actuator" as you mentioned.

I have a power bleeder and a couple of wrenches. Thank you very much!

On the older LS400 the actuator is under the air cleaner...on a gs400 it is right next to the master cylinder.

This is very simple, just complicated by the location.

1). remove air cleaner 2).then remove the air intake (with throttle body) which is about 2 10mm bolts and 2 10mm hose clamps. 3). the trac actuator is the one by the wheel well -- it has a bleed screw on the wheel well side (the abs is lower and forward). 4). attach a hose to the bleeder (brake fluid does eat paint) and direct it into a jar.(I used a fish tank hose) 5). the tricky part is to reattach the air intake (rotated at the clamp about 45 degrees about as far as the wire will let it turn) so that you can reach the bleed screw yet still start the car (without the air cleaner). I like to put the jar down where the air cleaner normally sits. (this IS from the manual) 6). Now you are ready..open the bleed screw (it may be 10mm as well)... some fluid should start to flow. 7). Start the car and let it idle. The trac pump will run (it is next to the master cylinder under a cover and you can hear it run) until the fluid level drops to the low warning point --this will make it stop. 8). Now you can add new fluid...the trac pump will kick in as you get above the low point and cut out if you don't pour fast enough. a) if you are slow and careful then the pump may cycle enough to set off the trac light (the original problem) in which case you need to restart the car. b)I like to run 1 whole regular sized bottle of DOT4 through the tank down to the low level point....close the bleeder.....fill the fluid tank (which is almost a whole second bottle) as the pump brings the system up to pressure...then bleed just a little more. 9). put everything back together 10). restart the car and top off the brake fluid tank.

Sometimes you will get the return of the light the first few times the trac or abs unit goes off, but that tends to dilute out.

We had a very damp year here (NE USA) and everyone I know with a series I had the trac light on. I fixed mine in May and theirs in June/July and none of us have had the light back on since. With the wet leaves and some snow I have had the Trac unit go off often and it is working much better than last year (less noise and better response).

If you go look at your car...I think you will see that this is easy to do. I think you can do it without moving the air intake, but it is so easy to move and makes it less likely that you will spill brake fluid.

If you do spill fluid just flush it with water (but not into the open air intake).

cheers,

rd

rd, thank you for the instruction. I do see the nipple with the red cover. Will do it tomorrow after picking up some DOT 4. I am sure many people will benefit from your post. In the future, just a simple Google search will find your post regarding " LS400 trac light on ". Thanks again.