Okay.. somebody please help this fool!

I don't know if it is because of the copious amounts of brew consumed shortly before doing this job, but I am stumped

Removed my calipers for a good cleaning whilst doing a routine brake job. Put everything back and bled the calipers using my NEW Motive bleeder.

Fired her up and found my "Brake Pressure" light flashing angrily at me.

Searched these fantastic threads and read speak of bleeding master cylinder. Ran back to my baby, but found no sign of bleeder valve on my 1983 US Spec. I found a port that has a regular screw in it.. that cannot be it - surely? It would make an awful mess.

Question.. do I bleed the MC. If so, where is the valve? If it is this screw - what is the best was to do it without shooting fluid all over the engine bay?

Help me guys..

 

Isn't that light a brake fluid level warning?

If so, did you drain the master cylinder when removing the calipers and perhaps the switch is stuck?

 

Not fluid level, I'm afraid... definitely "Brake Pressure". The MC did run very low. The plug that I used when I removed tthe calipers did not work too well on the first and I had quiet a puddle when I got back there.

 

Do you have any brake pressure?

You bled all 4 calipers correct?

 

The M/C is typically "bench bled" off of the car. There are kits with fittings to get hoses to transfer fluid into the M/C while it's held in a vice, but I've always added fluid into the ports while pumping. Crude, but it's worked for me enough to get things going. What you're trying to do is get fluid primed into the M/C as it is hard or impossible to get all of the air out when it's not primed. I've always been lucky in getting it bled enough to where any remaining air gets pushed out into the system at which time you can bleed at the wheels. Do a Google search on "bench bleed" and I'm sure you'll find something.

 

Also, for future reference, when removing calipers.....take a piece of wood and block the pedal slightly against the seat to put a slight amount of pressure on the brake pedal. It sounds contrary to logic, but it keeps mass quantitied of fluid running out of the lines when they are unhooked from the calipers. Just a dribble or two...

 

I have pressure and the pedal pumps up hard when the ignition is off.

 

Brake pressure warning is triggered by imbalance between the two switches on the master cylinder, the ones with three wires connected to each switch. Those switches also operate the brake lights. The warning light is cross-wired through the two switches so that it will light whenever one switch but not the other has pressure on it. If the light came on after you finished bleeding but before you pushed on the pedal, it's quite possible that some dirt was pushed into one switch by the bleeder. If it came on after you pushed on the pedal, it's likely that you genuinely do have a failure of one circuit. It's also possible that you have one switch stuck for some reason, and a new pair of switches is needed.

During the bleeding process, did you remove or rearrange any of the wires on the brake pressure switches? If so, it may just be a mix-up when replacing the wires on there.

 

That happened to me when I dealth with replacing the brake master, clutch master and slave. I bled the entire system and went for a drive. Got out of the drive and the same warning light went on. I disconnected the battery and the warning went away. I am not sure of the final cause but I took the connectors off and found a great deal of fluid. I cleaned the contacts and the light has never come back. The only other thing I can think of is that during the power bleeding I had to refill the master a couple of times which may have caused the pressure switch to trigger.

 

When you bled the system, did you bleed one caliper at time, or a front and a rear together?
If you did them one at a time, it is possible that the unequal pressure triggered the warning.

Try disconnecting the battery, if that does not remove the warning, try bleeding a front and a rear simultaneously.

 

I believe the warning gets triggered by the change in position inside the MC between the two circuits as outlined by drbob. Unhooking the battery resets the baseline, and you're good to go.

 

Gentlemen... you are geniuses!!! Apparently when I replaced calipers, etc and allowed the MC brake fluid to drop too low the switches on circuit identified trouble.

The bleed etc was successful, but all that she needed was to reset the baseline. I disconnected the battery and everything if fine.

Thanks for all the input fellows and TG for Rennlist!!