'90 Ls400 Trac/abs Don't Work When Its Cold, No Codes

[fopedush]

Hi everyone. I've got a '90 LS400 that I recently picked up at police auction for close to nothing. I've made a ton of repairs myself and it is now in nearly pristine condition, but one problem continues to elude me.

Whenever it is cold outside, say between 15-30F, the traction control and ABS don't work. When I start the car, the 'TRAC OFF', 'ANTILOCK', and 'TRAC' lights come on and stay on for the duration that the car is running. During this period, of course, the trac and ABS are totally nonfunctional. Sometimes, after running the engine for 15-20 minutes and getting everything warmed up, I can kill the ignition and restart the car, and the two systems will work just fine, with none of the lights on the dash coming on.

Here is an image of the dash while the problem is occurring

:

I've checked for diagnostic codes for both TRAC and ABS (as well as all the other systems), and there are none whatsoever. This car is a deathtrap in the snow without traction control and ABS, so I'm pretty desperate to figure out what the problem is here and fix it.

Any idea where I should start? Any suggestions are welcome.

[fopedush]

Bump?

I had searched the forums before posting this and found nothing, but I just searched again using some different keywords and found this thread: http://us.lexusownersclub.com/forums/index...d&pid=25193 . From the looks of it this guy was having the exact same problem I am now having, but the replies are a little cryptic. Should I be looking into diagnosing the accumulator?

[90LS400Lexus]

Not sure... sounds like an unusual problem. I have never heard of temperature effecting ABS or traction control. Do you have alot of ice or cold temps in your area? Sounds almost as if something may be getting wet and its icing up and causing it, but this is a guess.

There are alot of knowledgable folks on here and I am sure someone will have more info.

[dpellet]

Not sure... sounds like an unusual problem. I have never heard of temperature effecting ABS or traction control. Do you have alot of ice or cold temps in your area? Sounds almost as if something may be getting wet and its icing up and causing it, but this is a guess.

There are alot of knowledgable folks on here and I am sure someone will have more info.

Cold weather has everything to do with it as I have a 91 and live just north of Calgary and have the same occasional problem.. I found a quick bleed of the TRAC System should help out as I did it and have not had it re-occur yet. The bleed plug is on the accumulator just under the intake system. Lots of pressure there so make sure your bleed line is secure. Search out bleeding brake system and you should find more details.

[steve2006]

Check the wiring to the trac pump relay and trac pump, check the high pressure pipe from the pump is secure.

To bleed the accumulator.

Connect a vinyl hose to the accumulator bleed plug and loosen the bleed plug,start the engine and operate the traction pump motor ( no info as to how but removing the pump relay and shorting out the relay contact connections, pins 1 and 2 should power up the pump motor manually), until all the air bubbles have been bled out.

Retighten the plug to 74"LBS ( inch/pounds) or 8.3n.m..

With engine still running top up brake fluid reservoir.

[dpellet]

Check the wiring to the trac pump relay and trac pump, check the high pressure pipe from the pump is secure.

To bleed the accumulator.

Connect a vinyl hose to the accumulator bleed plug and loosen the bleed plug,start the engine and operate the traction pump motor ( no info as to how but removing the pump relay and shorting out the relay contact connections, pins 1 and 2 should power up the pump motor manually), until all the air bubbles have been bled out.

Retighten the plug to 74"LBS ( inch/pounds) or 8.3n.m..

With engine still running top up brake fluid reservoir.

Not to discount procedure above but as soon as you start the motor the accumulator is checked for pressure and at that moment the pump motor is running and the bleeder will pump out at high pressure (make sure you don't let it pop off.) I simply started the car briefly letting the fluid spurt out, tighten bleeder, turn off car, top up master cylinder then do it again until no bubbles are viewed.

I'm willing to bet it's the same problem. Mine used to do this all the time in the winter when the temp goes below -20 and high wind chill values & or high humidity. On first start of the day the trac lights would come on and stay on, system down. I would just let the car warm up for 10 minutes and re-start when ready to go and it never failed the trac would work thru system check and lights would go off after that for good for the day. When the weather finally warmed up I did the bleed and no prob's since.

Cheers!

[fopedush]

Thanks for all the replies. I will definitely try to bleed the system as soon as I get a chance. Temperatures have been around 5-10F during the day and -5F at night though, so it might be a bit before I have a chance to try it. I'll be sure to let everyone know whether or not it worked.

[platoribs]

Thanks for all the replies. I will definitely try to bleed the system as soon as I get a chance. Temperatures have been around 5-10F during the day and -5F at night though, so it might be a bit before I have a chance to try it. I'll be sure to let everyone know whether or not it worked.

Any follow up report on this?

Having just bought a 91 that's demonstrating the same issues, in Chicago, in the winter...

...recon I'll be doing the same thing.

[dpellet]

Thanks for all the replies. I will definitely try to bleed the system as soon as I get a chance. Temperatures have been around 5-10F during the day and -5F at night though, so it might be a bit before I have a chance to try it. I'll be sure to let everyone know whether or not it worked.

Any follow up report on this?

Having just bought a 91 that's demonstrating the same issues, in Chicago, in the winter...

...recon I'll be doing the same thing.

Try to have the system bled, this part of the braking system is not usually bled when standard break work is done especially if done by a non-lexus mechanic. I think it's just neglect over the years that allows a little moisture to get into that part of the system and when it's cold the intitial test does not pass due to lower than required pressure.

As you mention as soon as temps moderate you will not have that issue. I'm near calgary so when temps dip below -10C I always had this issue. I used to put a hairdryer in the engine compartment right over the trac pump and let it run on high for a couple of minutes and presto, no problems! Since I bled it seems to be ok.

Hope this will help!

[Brash001]

This is going to sound crazy but this is a true story, corroborated twice on my 2007 GS450h...

The problem is that my brake level went out of range. I swear that this is what was determined to be the problem and it may be your problem too. I had the exact same problem as you. In cold temps the brakes and all the lights were an issue. Once the car warmed up everything would become operational and all the lights would reset. You see, my brake pads were worn and this caused my brake fluid to drop below a certain range in the master cylinder. I took it to the dealer and they reset the computer and added just a little fluid.

Light problem solved....for now.....

So I bought new pads and did the pad change. Great right? Nope, now the fluid had risen ltoo high since and I did not suck out enough fluid and/or it was just too sensitive to the fluctuation in the master cylinder fluid. I called the dealer again, took it in and they reset the computer....no proble going om 9 months.

It has everything to do with the brake fluid level in the master cylinder and resetting the computer. No kidding.

I feel really confident since I had all the lights shown above and my brake power assist would cut out till the car got sufficiently warmed...or the brakes got sufficiently warm. Absolutely nuts but what a gem to know that this is nothing that requires anything in the way of surgery to resolve.