Brake warning light

[Tom Thomson]

How come the brake warning light came on in my 90 pickup?
Plenty of nice clean fluid. Is there a differential pressure switch that I can't find?
tommyt

 

[KLF]

Only 2 things will turn on that light: low fluid in the brake MC reservoir, or the e-brake is on.

Check the switches, I've seen them both fail after 20+ years.

A failing alternator will also cause it to flash sometimes, but also the Charge light will be on.

 

[toydude13]

My truck is a bit older but it had a sticky e-brake switch. It must have been dry after so many years 'cause lubrication fixed it.

 

[rocktoy74]

My truck is a bit older but it had a sticky e-brake switch. It must have been dry after so many years 'cause lubrication fixed it.

I agree especially with these older rigs, just spray or lube the switch Itself with something and then use a light coat of general purpose grease and coat the while rod and the teeth of the shaft