73 Plymouth Brake Fault Indicator

[A_Roldan]

Hello to all.

OK, after digging through a few pages here, digging through pages of Google search results, and doing a search in these forums I still can't find any clues.

-Please help-

I have a '73 Plymouth Satellite and the in-dash BRAKE indicator is lit. It started blinking on-and-off two days ago and now it is on steadily - didn't turn off yesterday at all.

The fluid level is full. The pedal feels good/solid. There is no noticeable change in the car's stopping abilities. I see no leaks.

I looked on the master cylinder and the proportion valve but I don't see any wire leads or sockets (thinking I'd check for loose connections...).

So what is this light indicating exactly and where is it getting the "fault" from? I'm pretty sure someone here will be familiar with the system. Otherwise, I'll start tracing the wires from the dash back until I find it...this weekend.

Thanks.
~Angel

 

[RustyRatRod]

That *usually* means there's air in the system. Do you have power or manual brakes? If you have power brakes, it's sometimes difficult to tell if the master cylinder is bad. Since the rear of the master cylinder is where it will leak and it is bolted right against the booster, you will sometimes not notice a leak there, because it leaks right into the booster. So for that, simply unbolt the master cylinder from the booster, pull it back and look at the back side to see if it's wet. For manual brakes, you need to look under the dash, where the brake pedal rod comes through the firewall. Look into the rear of the master cylinder and see if it looks wet. Also of course, check around the boots for the calipers and wheel cylinders. Pry the boots back on the wheel cylinders and if you get ANY fluid, they need replacing. Likewise for the calipers but you don't have to pry the boots back there. If there is any wetness there, they should be replaced. I say replaced....but I rebuild all my own stuff. WHeel cylinder kits are like 3 bucks, caliper kits are about 10, master cylinder kits are about 10-15. Some people are not comfortable doing that though.

 

[A_Roldan]

Nice. Thanks for the information.

They are Power Brakes so I will do all the checking and inspecting you just laid out for me. I appreciate it. I put new pads on the front this past spring and new shoes on the rear this last summer so all the parts were cleaned then. Should be an easy thing to do all the inspecting and I'll repair or replace whatever I find that is not 100%.

Thanks again for the quick reply and all the info.
~angel

 

[69Bee]

If I remember correctly, that light will come on when the E-brake is applied. Check the switch on the brake assy behind the left kick panel under the dash. You might just have a switch that is grounding out.

 

[Hemi Rebel]

If I remember correctly, that light will come on when the E-brake is applied. Check the switch on the brake assy behind the left kick panel under the dash. You might just have a switch that is grounding out.

X2. Does the e brake work? Could just be the pedal is not all the way up. Pull the release handle and lift up on the e brake pedal and see if the light goes out.

 

[RustyRatRod]

Yeah the E brake thing too. I had forgotten that. Danged if I wouldn't check that first.

 

[72RoadrunnerGTX]

There are two switches that trip the brake system indicator, as mentioned the parking brake, and the pressure differential switch in the combination valve assembly. Disconnect the leads that connect to the switches one at a time to determine which one is providing the ground activating the light. If it’s the pressure differential switch, you will need to locate and repair the hydraulic failure that tripped it, as described above, and then reset the switch. Check the FSM, details are located there to reset the switch.