Easy one?

[Cody Forbes]

Patient is my '86 5k no-T no-Q. The red triangle brake fault icon keeps poping up (with the dreaded tripple beep of course) at random times while driving down the road. Zero reproduce-ability. In my 19 mile (each way) commute it will happen two to three times one day, then the next will be non stop - no pattern.

Now AFAIK the 3 things that trigger that light are the pressure switch on the booster, the brake fluid level, and the hydraulic fluid level. Fluid levels are both ok, and the low pressure switch IME 99% of the time only trips the light when using the brakes in a car with a bad bomb, while this problem happens on flat level highway while maintaining speed. In a futile attempt to narrow it down I tried disconnecting the 3 switches one at a time, and eventually all at once, with no luck - with all 3 disconnected the light still pops up at random.

Yes, it has green stuff and only green stuff in the system. No, it actually doesn't leak much at all and I've never replaced any hoses. Yes, the bomb is mostly bad and I can't afford a new one. Yes, I normally leave the switch in the booster disconnected so the car doesn't beep at me every time I hit the brakes hard.

There simply must be another sensorw/switch that trips the diag system into throwing that light, but I wasn't aware of such an item. Please do tell!

-Cody Forbes
http://www.5000tq.com
'87 5ktq - Fast.
'86 5ktqCD
'86 5k BEEP BEEEP BEEEEP!
'86 5k