Brake Press light flashing

[StangGuy67]

Replaced my bad brake master cylinder yesterday with a brand new ATE OEM part. Part came with new O ring. Also came with both brand new switches. Cleaned out reservoir, and added clean brake fluid. Bled all 4 corners, starting with the rear. Brakes work great, but can't get rid of the dreaded flashing brake light, along with the more irritating (!) in two places on the dash. Car is a 1980 928. What am I missing?

Thanks...

[MPDano]

Are your new switches actually working? Also, are all your brake sensors (4) intact? Wiring to brake fluid level sensor may also need to be checked. Is this an 80 US?

[Mrmerlin]

Make sure the connectors on the switches are clear of corrosion,
if thats not working try swapping the connectors to the other switch

[StangGuy67]

I have to assume that the new switches on the new master are working. Fluid level sensor was stuck, and "Brake Fluid Level" light was also flashing, but a few taps on the reservoir solved that problem.

One of the rear sensors is not working, and has been like that for the two years I've owned the car. Did not seem to affect the "Brake Press" light prior to the new master cylinder.

Wires and plugs leading to the switches are tight, and reversing them does not seem to be an option. I did notice, however, that the connector for the plugs are facing in the opposite direction from the old master cylinder, though that shouldn't have anything to do with my problem.

Car is an '80 US.

thanks!

[nosnow4pc]

Disconnect the battery for a few minutes to reset the light.

If the light comes back on you may have a bad master or poor bleed.

[Normy]

You changed the brake fluid; Did you bleed the slave...

WHOOPS! You own an automatic. Sorrry, disregard-

N

[Normy]

Are you 100% certain that you've got all of the air out of the system? Brakes can be a pain in the ass with regard to bubbles!

N!

[StangGuy67]

Car is a 5-speed, but I was under the assumption that the clutch slave did not have to be bled, as no air was introduced into that part of the system.

I'll disconnect the battery, and see if that works. Bled system until all air was out, saw quite a few "lumps" come out of the lines.

Thanks!

[Mrmerlin]

did you pre bleed the MC before installing it??
Does the MC have a bleeder at the tip of it??
How many hose connections are coming out of the MC??
Try cracking each line and letting it gravity bleed at the MC, you may find some air bubbles out of the fittings, about 2 to 3 turns from each fitting should be good , dont mess with the switches

[StangGuy67]

Update on flashing light:

I started with the easiest fix first (disconnect battery) and that was the cure!


Thank you to everyone that offered a solution. I hope to be able to repay that favor in the future.

[Fredfox]

Always good to see closure.

[MPDano]

Yes, thanks for posting your fix.