Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
This Jeep arrived with no rear brakes. The "BRAKE" light was illuminated on the dash triggered by the combination valve sensor. The front brake circuit seems to be functioning normally. Front Disks, Rear Drums on this one.
As a quick first step we attempted to bleed the right rear using the manual brake pedal method. No fluid was pushed through and we saw no obvious leaks. Quick check of left rear, side thing. At this point we started working our way forward. At the connector about half way forward, no fluid moving when slowly working the brake pedal. Next we removed the rear brake line at the combination valve and slowly moved the pedal. It spit out a combination of fluid and air. Pressure between the MC and the combination valve seems good on both circuits. In hindsight, at this point I should have bled the MC and combination valve and then starting working back down the system towards the rear brakes. What we did was replace the combination valve (parts changer, ugh!). We bled the MC and then attempted to bleed again at the rear wheels. Nothing. If fact, when bleeding at the rear wheels the fluid level in the MC reservoir does not change. If I remove the connector at the combination valve and depress the brake, fluid does shoot out. If I then reconnect the line and attempt to bleed, absolutely nothing moving thru the system. the fluid is the reservoir does not move down.
I'm open to ideas. Today I plan to start by bleeding the MC again, then bleed the combination valve and start working back toward the rear wheels. Am I missing something. I can see where a leak in the brake system would trigger the sensor in the combination valve or a bad combination valve could restrict fluid to the rear circuit, but I'm not seeing that.
Found the issue. The combination valve piston closed the rear brake circuit since there was no pressure. I manually centered the piston in the valve and we were able to add fluid in the rear and then found the problem that started the whole sequence of issues.
