Brake light on after dual diaphragm install

[Geek]

Just went through putting the dual diaphragm and 96 master cylinder on my truck, now the brake line is always in.

I did also replace the proportioning valve and some of the lines and calipers and wheel cylinders.

I had a problem bleeding the brakes and ended up replacing almost every thing.

The brake do work now and was able to bleed them.

 

It is an 88, 4.0, aw4

[Strokermjcomanche]

Did you grind/file down where the pushrod makes contact with the switch?

[Geek]

Sorry, I should have said which light, it is the brake light on the dash. I replaced the switch on the peddle with the one Cruiser suggested. It has the torque converter and the brake light switch hookup. 

[Strokermjcomanche]

It’s Probably the Switch/sensor on the proportioning valve triggering the light. I think there’s a procedure to make the light go off ( that’s if you do have enough brake pressure) . Simone else can chime in on that .. 

[jdog]

Did you bump the ebrake wiring

[gogmorgo]

When you say you replaced the proportioning valve, do you mean you eliminated the height sensing valve, or did you just swap out the distribution block?

[Geek]

It is possible i bumped the ebrake, will have to check that.

 

I replaced the proportioning valve with one from a YJ, I believe most of the earlier jeeps used the Kelsey Hayes proportioning valves.

 

This is the one I used here,

MBM, Brake Proportioning Valve Kelsey Hayes Style | Best Prices & Reviews at Morris 4x4 (morris4x4center.com)

 

The brakes work much better now, they feel more like my XJ and the peddle is firm.

 

[Geek]

Yes, I also deleted the load sensing on it as well.

[mjeff87]

To reset the switch, it needs something ridiculous like 500 lbs of pressure.  Try sitting in it (engine off) and mash down the pedal, HARD.  It will make a little "click" sound when it resets.

 

 

[AZJeff]

1 hour ago, mjeff87 said:

To reset the switch, it needs something ridiculous like 500 lbs of pressure.  Try sitting in it (engine off) and mash down the pedal, HARD.  It will make a little "click" sound when it resets.

 

 

There is another way to reset the switch, but it depends on how easily the small spool valve in the distribution block will move.  Some can be VERY difficult to get them to slide.   Here is what you do:

 

Unscrew the plastic switch body from the distribution block and look down into the hole in the block with a flashlight.  You will see the spool valve in the bottom of the hole.  This is what the plunger on the switch is in contact with.

 

CAREFULLY using a small pick, you can usually push the spool valve back to it's center position.  (The center position is where the diameter of the spool valve is smaller than the rest.)  Once the spool in centered, the switch can be reinstallated, and should remain off.