Amskeptic

This was an unusual one.

Ever since I have owned this '92 LS400, the "Trac" light has leered from the instrument cluster.

At the same time, I have heard weird noises most noticeably after start-up when putting the car in gear and trolling slowly out of parking lots. It was a rythmical sshhhhuuuuunk sound coming from somewhere in the dashboard region, and I chalked it up to "very important things the car does automatically".

At the Starbucks in Erie Pennsylvania, I finally got around to reading the Trac codes. There was a 19 "- TRAC motor ON and OFF operation is higher than a predetermined number of times (accumulator pressure leakage)!"

Accumulator pressure leakage . . . that sounds bad. OK, no external leakage of anything having to do with brake fluid, look at the level in the reservoir, it is most certainly not low, as a matter of fact, it is looking sort of over-full. And the cap on the brake fluid reservoir even says "do not over-fill" and it says (did you know this?) "check only with the engine running".

So, I wicked the brake fluid level down to the upper mark on the reservoir with a series of carefully inserted and disposed-of paper towels. The Trac light came on when I pulled back on the interstate and I thought, well, at least the reservoir is not too full.

Aha, but the next day . . . the Trac light stayed off AND I got only one sshhhuuuuuunk sound from beyond the dash.

I think what was happening was foaming of the brake fluid, and that made the accumulator pressure build-up go right back down when the pump shut off as you would expect if you had compressible air in the brake lines, so it did a series of pump-ups that triggered the Trac code. After I re-adjusted the reservoir level, it took a little time for the bubbles and what-not to clear from the lines. Now the accumulator just primes right up.

I like this car. It is getting better and better.
Colin

Bali26

You mean the brake fluid was foaming because of overfill?

Or you took off the bubbles from top?

lexondubs

Wow mine was real high 2 after doin my rear pads i took most of it out but its still a little high and my trac light is on im gonna try this!!

Amskeptic

Oh yesyesyes, look at that, right here folks.

I'll bet the reason my Trac light was on was because the last brake pad replacement before I bought the car, the technician did not check to see if the reservoir level was too high.

If your brake reservoir level is down, you do not necessarily top it off. You might want to check to see if your pads are getting worn. When you push the pistons back in to fit the new pads, the level in the reservoir is going to go up. Had you topped it off before pad replacement, you will need to re-adjust the level back down.
Colin
(p.s. no bubbles were present in the reservoir when the level was high. I am purely speculating about why the accumulator pump was cycling)

lexondubs

tried this and my trac light is still on lol

Amskeptic

Get thee a code number off the trac warning light.
Colin

Boyscout

iTrader: (3)

my trac light comes on about a minute after i start driving and stays on.

i first started noticing this after i had my rotors replaced and my fluids changed (including brake fluid).


gonna check the level this week.


thanks for the tip!

lexondubs

Well since nobody ever tells how they fix things ill add my fix it there was no fuse in the trac space under the dash :S so I put the required fuse in and works mint and no more light !