Carnut, i was told that the abs computer reads the travel of the piston in the calipher and when it goes out of range the red brake light will come on.when the brakes get low you have more travel of the piston therefore "red brake light" which probably explains why it only comes on when i use the brakes.
yes low pads can send in the red brake light( as told to me by dick).the abs computer reads the travel of the piston in the calipher and when it goes out of range quess what? (i think i got the wording correct) anyway it's off to the repair shop for pads and flush.
today i think i found the answer to my brake light problem.what do you think.i took my beast to work.it is about 6 miles one way. on the way the red brake light came on 3 times ans all 3 times i pulled over and re-started the beast.on the way home it was about the same but only my radio was off and i noticed that everytime i stepped on the brakes i could hear a quiet motor cycling. it would run for 3 seconds ( i counted).qrriving at home i open the hood a had my daughter step on the brake.everytime she did i could hear a motor run,it was a smll cylindercal motor in front of the master cylinder and just unde the intake.i know it is not normal for it to cycle in that manner.i think maybe a new accumulator should be ordered.
I think i finally found the culpret to my brake light problem.today i took the beast to work.it is a one way journey of about 6 miles.during this trip to work the brake light came on 3 times and all 3 times i pulled over and restarted my beast and the brake light cleared. going home was about the same but this trip my radio was off and i heard a very quiet motor cycling. i came to realize that this motor cycled for 3 seconds everytime i stepped on the brakes.( I COUNTED THE SECONDS).when i got home i opened the hood and had my daughter step on the brake petal and everytime she did the motor would run for 3 seconds.it was the cylinercal motor in front of the master cylinder just under the intake ductwork .it has BOSCH on it's housing. i think that might be the accumulator. might it be going bad? maybe a recharged one might be in order.
Each and every time the brakes are depressed this Bosch motor runs. That is normal!!! Please understand I've owned one and was the assistant service mgr at a Cad dealer when this car was introduced in 87. You have followed Dicks diagnostics to the letter correct? (allantesource.com) I had the misfortune to have this motor fail to turn on once while leaving the dealership. I had virtually no brakes!! without this motor running you have no pedal leverage. Per Dicks diagnostics, this motor should run a certain number of seconds once the pedal has been pumped 20 to 25 times ,engine off, to deplete the accumulator. If it runs too long the accumulator is faulty. You need to purchase a factory service manual to verify what is and what is not normal.
carnut, i have ran the diagnostics from allantesource and it checked out ok.saturday i had my mechanic look at my brakes and he said the pads and rotors looked brand new. he didn't know how to flush the allante's bosch brakes so i passed on his flush until i can get to my allante tech. i also noticed than when i step lightly on the brake petal the light will come on but if i step firmly on the petal the light won't come on. is there a switch or something on the brake petal.
well now i have come to the conclusion that it's a failing accumulator that is causing the red brake light.i am going to order a recharged one and see what happens.
If it passed the allantesource diagnostics, then you dont need an accumulator. Hard to help not being there but have you again verified the float within the master cyl isn't hanging up? My 88 had the little plastic square float cover pop off the master cyl cap giving me false readings. Was necc to replace the cap to fix it.
today i messed with the cap/float assembly to no avail. i also spoke to dick today and i adjusted the brake switch to no avail so now i offically "give up" on my brake problem.next thursday off she goes to my allante tech.i hope he can bring me some good christmas news.
Re: brake light coming on! 
