1SLwLS1

iTrader: (6)

When I first bought the car, the previous owner said if I go over 90 MPH, those (3) warning lights would kick on. He said it was not really an issue as when you would re-start the car, the lights would stay off until 90+ MPH was achieved again. He contributed this to some kind of error in the 12 bolt swap. Well sure enough, the conditions presented themselves just as he described. A few months later, I swapped rear end lube. I put on a new Fel-pro gasket, (2) quarts of regular 80w-90, and 4 oz of limited slip. I did this due to the low speed turn popping sound that is oh so familiar with the limited clutches.

That problem went away after that. Those lights would NEVER come on. Fast forward to a month ago. The engine flooded and hydrolocked, but no water got on the inside and the water wasn't deep when the back of the car went through, the nose cleared quite a path . Now it seems that those lights will come on in the afternoon. I swapped fluid again, using Castrol Hypo C 80w-90 and 4oz of GM limited slip additive. I drive to work in the morning, ambient temps of around 80F, then I drive for lunch, ambient temps of 95-100F, still no lights, and then I head home around 4PM with ambient temps of 100+F. The lights will then kick on, either when I start the car in the afternoon or after a mile or two of driving towards home. I added about 1/4-3/8 of a quart more fluid thinking maybe all of the (2) quarts didn't make it in.

Last night I pulled the rear ABS sensors thinking maybe they are fouled. They sure had quite a bit of metal on the magnetic tips! I will know today when i leave work if the problem still arises, but back to the original topic, what are the conditions for "ABS INOP" & "TCS OFF" & "BRAKE"? Now, just to remove the obvious, I checked the brake fluid reservoir, it is about 1/8" below MAX.

1SLwLS1

iTrader: (6)

Just went to get something from the corner store. Went WOT through 1st and 2nd due to the driver in front of me driving 30MPH in a 40MPH zone. After that, the lights came on. Weird...

bigboykilroy

iTrader: (48)

Wheel Speed Sensors possibly, what size front and rear tires are you running? If they are missmatched height sizes they can throw those codes.

1SLwLS1

iTrader: (6)

BFG 275/40/17 and Nitto 315/35/17 out back. Both on 9.5" wheels. I just finished reading a 10 page thread that started 3 years ago. What a mess these car's ABS systems are.

bigboykilroy

iTrader: (48)

BFG = 25.7
Nitto = 25.7
You have matching Heights so that is not the problem.
I would now look at the wheel sensors, it may be as simple as taking them out and cleaning the road grim off of them, my tahoe did the same thing and that is all it was. Yes these fbody ABS systems can be a pain in the *** when they malfunction.

1SLwLS1

iTrader: (6)

Yea, I did the rears on Wednesday night. They were filthy, but I haven't done the front yet. I am thinking it is heat related, particularly the control module under the hood. It seems it only acts up after a hard run or in the afternoon after my car has been driven a while. Thats what makes me think it is heat related. I am not worried though, as ABS still works as well as cruise control. Just a nuisance.