'96 OBS, 170k

Due to operator error I got air in the master cylinder, don't make my mistake.

After bench bleeding the master cylinder in-car I still can't get the dash brake warning light to go out. I presume this means that the dash light switch in the master cyl is closed due to an air bubble. I followed morgans bench bleed method (plumb two male fittings with hoses from the MS back into its reservior and pump the pedal). If I pump hard, I see tiny bubbles maybe from cavitation?, if I pump slow, no bubbles. How long does it take to get the air out?

 

The problem is complicated by a short in the dash somewhere. If I unplug the master cylinder connector, the light is still there (dim). If I pull the parking brake or plug in the master cylinder connector, the dash light goes bright.

 

+1 for the motive power bleeder, great product for bleeding the brake slave cylinders. use the universal adapter for 2.6" yellow topped master cylinders.

The little float in the tank of cyclinder may be stuck down. Use small screwdriver and get it to raise back up.

Thanks, so that is what that float is for! I can't see under the float. I'm assuming there is a switch contact under the float that is somehow stuck...the float is free...

ahhh, I see the magnetic reed switch insert under the reservior...problem solved. Thanks again for the help.