Proportioning brake valve problems?

Sphinx

Sphinx

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Joined
Jan 31, 2022
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24
Location
Qc, Canada
Hello guys, I have a problem with the brake light switch in my dash...I replace all my bake system except master and proportioning valve. All line, flexible hoses , caliber and rear cylinder are new. I bleed all the system, but the brake light still on. I re-bleeding the system and this time, (with my brother in the jeep) we are listening a strange toc toc coming from the master/proportioning valve...but only when we are bleeding the front passenger side. The light goes out and coming when we press the pedal without bleeding.

I remove the sensor from the proportioning valve and when my brother have pressed the brake the first time, I see the "rack" inside move backward. And he don't move forward after...

I'm confused with this...an idea?
 
Sphinx said:
Hello guys, I have a problem with the brake light switch in my dash...I replace all my bake system except master and proportioning valve. All line, flexible hoses , caliber and rear cylinder are new. I bleed all the system, but the brake light still on. I re-bleeding the system and this time, (with my brother in the jeep) we are listening a strange toc toc coming from the master/proportioning valve...but only when we are bleeding the front passenger side. The light goes out and coming when we press the pedal without bleeding.

I remove the sensor from the proportioning valve and when my brother have pressed the brake the first time, I see the "rack" inside move backward. And he don't move forward after...

I'm confused with this...an idea?
Click to expand...

The shuttle valve shifts when the differential pressure is too high on one side of it as a way to slow down the loss of brake fluid if a leak happens.

The system should be bled with the key on. If you push the pedal down and the light turns on, close the bleeder and stomp on the pedal a few times and that should turn it back off. Do another bleed stroke after it does, repeat the stomping each time it turns on. Alternately, there are lock out tools you can use in place of the sensor (switch) to lock the shuttle valve in place.

You should also check that all the bleed screws are on top since air in one or more of the wheel cylinders will let this happen.

Explain how you are bleeding, clearly please.
 
I open the bleeder, my brother press the pedal to the floor, i close the bleeder and he release the pedal. I start from the back passenger and i finish with the front driver side. But the only place that the light is blinking is on the passenger front caliper
 
Sphinx said:
I open the bleeder, my broyher press the pedal to the floor, i close the bleeder and he release the pedal. I start from the back passenger and i finish with the front driver side
Click to expand...

Good, as long as he does it with enthusiasm, you'll be fine. Check the bleeders, key on while bleeding, stomp the pedal if the light comes on until it goes off. If that doesn't do it, get it centered so the light goes off with the key on, parking brake off and use a lock out tool to hold the shuttle in place.
 
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mrblaine said:
Good, as long as he does it with enthusiasm, you'll be fine. Check the bleeders, key on while bleeding, stomp the pedal if the light comes on until it goes off. If that doesn't do it, get it centered so the light goes off with the key on, parking brake off and use a lock out tool to hold the shuttle in place.
Click to expand...

FYI. When he says “with enthusiasm “ he means it. Fixed my issues , a little enthusiasm and a lock out tool
 
mrblaine said:
The shuttle valve shifts when the differential pressure is too high on one side of it as a way to slow down the loss of brake fluid if a leak happens.

The system should be bled with the key on. If you push the pedal down and the light turns on, close the bleeder and stomp on the pedal a few times and that should turn it back off. Do another bleed stroke after it does, repeat the stomping each time it turns on. Alternately, there are lock out tools you can use in place of the sensor (switch) to lock the shuttle valve in place.

You should also check that all the bleed screws are on top since air in one or more of the wheel cylinders will let this happen.

Explain how you are bleeding, clearly please.
Click to expand...
Where can one find such a lockout tool?
 
mrblaine said:
The shuttle valve shifts when the differential pressure is too high on one side of it as a way to slow down the loss of brake fluid if a leak happens.

The system should be bled with the key on. If you push the pedal down and the light turns on, close the bleeder and stomp on the pedal a few times and that should turn it back off. Do another bleed stroke after it does, repeat the stomping each time it turns on. Alternately, there are lock out tools you can use in place of the sensor (switch) to lock the shuttle valve in place.

You should also check that all the bleed screws are on top since air in one or more of the wheel cylinders will let this happen.

Explain how you are bleeding, clearly please.
Click to expand...

mrblaine said:
The shuttle valve shifts when the differential pressure is too high on one side of it as a way to slow down the loss of brake fluid if a leak happens.

The system should be bled with the key on. If you push the pedal down and the light turns on, close the bleeder and stomp on the pedal a few times and that should turn it back off. Do another bleed stroke after it does, repeat the stomping each time it turns on. Alternately, there are lock out tools you can use in place of the sensor (switch) to lock the shuttle valve in place.

You should also check that all the bleed screws are on top since air in one or more of the wheel cylinders will let this happen.

Explain how you are bleeding, clearly please.
Click to expand...

Where can one find such a shuttle lock tool?

The rear line rusted out on my 99 two years ago and I replaced everything but the master and combo block (just learned it isn't just a prop valve!). I've had an intermittent brake light ever since.

I'd like to lock the shuttle and bleed the brakes again since the pedal isn't as firm as it should be.
 
Weasellee said:
Please explain
Click to expand...

The shuttle valve moves back and forth. It needs to be centered for the system to bleed properly. If the switch plunger isn't in the detent, then it needs to be.

If it won't center and turn the dash light off, then it needs to be removed, rear port pull and then the end of the valve can be pushed or pulled carefully to center the detent on the plunger or lock out tool. The lock out tool is useless unless it screws into the detent to hold the shuttle from moving.

1704510620826.png
 
mrblaine said:
The shuttle valve moves back and forth. It needs to be centered for the system to bleed properly. If the switch plunger isn't in the detent, then it needs to be.

If it won't center and turn the dash light off, then it needs to be removed, rear port pull and then the end of the valve can be pushed or pulled carefully to center the detent on the plunger or lock out tool. The lock out tool is useless unless it screws into the detent to hold the shuttle from moving.

View attachment 488762
Click to expand...

Ahhh. Very nice explanation. Thank you
 
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