What is wrong when the brake warning lite is on when the key is in run an nothing is hooked up.the switch in the pro. valve is disc. an parking brake switch is to why is the lite on could someone please tell me Thanks.

 

If the switch is disconnected from the prop valve and parking brake, it's gonna be illuminated, showing you a fault. Hook them up and the light should go off. Unless your PB or Prop valve switch is bad.

Do you have service manual?

 

Bob I did that also an it still stays on I even took the switch out on the pro. valve an tested it an it seems to work. is their any other way to test it Thank you .

 

Did you test the e brake switch? Are the brakes bled and work?

 

yes I did check the ebrake switch and also bled all the brakes.

 

let me check sumtin...

 

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OPERATION OF COMBINATIONVALVE
The metering or hold-off section of the
combination valve limits pressure to the front disc
brakes until a pre-determined front input pressure is
reached, and until the rear drum brakes are activated
(rear line pressure must overcome the rear brake shoe
return spring tension and clearance between linings
and drums before the rear brakes actuate). There is no
restriction at inlet pressures below 3 psi to allow for
pressure equalization during nonapply periods.
The proportioning section of the combination
valve proportions outlet pressure to the rear brakes
after a pre-determined rear input pressure has been
reached. This is done to prevent early rear wheel
lock-up under heavy braking loads.
the valve is designed to have a "by-pass" feature
which assures full system pressure to the rear brakes
in the event of a front brake system failure. Similarly,
full front pressure is retained in the event of a rear
brake pressure failure.
The pressure differential warning switch is
designed to constantly compare front and rear brake
pressures Jrorri the master cylinder and energize the
warning light on the dash in the event of a front or rear
system failure. The valve and switch are so designed
that the switch will latch in the "warning" position
once a failure has occurred. The only way the light can
be turned off is to repair the failure and apply a pedal
force to develop approximately 450 psi line pressure
PARKING BRAKE LAMP SWITCH
The parking brake lamp switch assembly is bolted .
to the hand brake mounting bracket and. is actuated by
the parking brake hand lever.
This switch is nonadjustable.
COMBINATION VALVE
Testing Electrical Circuit of Combination. Valve
, When removing the electrical wire connector
from. . the pressure differential switch, it ·is
recommended that you squeeze the eliptical shaped.
plastic locking ring and then pull up. This will move
BRAKES 5-15
the locking tangs away from the switch. A pair of pliers
can be used to aid in the removal of the connector.
TO REMOVE FROM SWITCH:
DEPRESS SIDES OF CONNECTOR (A) A
TO RELEASE TABS (B).
520209·5
Fig. 13 Removing Brake Switch Connector
1. Disconnect wire from switch terminal and use a
jumper to connect wire to a good ground.
2. Turn ignition key to "On" - warning lamp should
light. If lamp does not light, bulb is burned out
or electrical circuit is defective. Replace bulb or
repair electrical circuit as necessary.
3. Turn ignition switch off and reconnect wire to
switch terminal.
1++1 Remove or Disconnect
The combination valve is not repairable and must
be serviced as a complete assembly.
On some cars, hoisting may be necessary.
When removing the electrical wire connector
from the pressure differential switch, it is
recommended that you squeeze the eliptical-shaped
plastic locking ring and then pull. This will move the
locking tangs away from the switch. A pair of pliers
can be used to aid in the removal of the connector.
1. Hydraulic lines at combination valve. Plug lines
to prevent loss of fluid and entrance of dirt.
Warning switch wiring harness from valve switch
terminal.
2. Combination valve.
l++llnstall or Connect
1. Combination valve.
2. Warning switch wiring harness to valve switch
terminal. Hydraulig)ines to combination valve.
3. Bleed entire brake system. Do not move car until
a firm, brake pedal is obtained ... ·.·.
Testing Warning Light Switch Portion of
Combination. Valve
1. Attacha bleeder hose to a rear brake bleed screw
and immerse the other end of the hose in a
container partially filled with clean brake fluid.
Be sure master cylinder reservoirs are full.
5-16 BRAKES
1-MASTER CYLINDER
2-BOOSTER
3-DASH PANEL
OJ
I VIEW
Fig. 14 Combination Vaive to Master Cylinder Mounting
2. Turn ignition switch to "On" - open bleeder
screw while a helper applies moderate pressure to
the brake pedal. Warning lamp should light.
Close bleeder screw before helper releases brake
pedal.· Reapply brake pedal with
moderate-to-heavy pressure. Light should go out.
3. Conventional System:
a. If the front brakes were used in Step 1, then
attach bleeder hose to the front brakes and
repeat test.
b. If the rear brakes were used in Step 1, then
attach bleeder hose to the rear brakes and
repeat test.
4. Diagonal - Split System:
a. If a caliper was used in Step 1, then use
caliper on opposite side and repeat test.
b. If a wheel cylinder was used in Step 1, then
use wheel cylinder on opposite side and
repeat test.
5. If warning lamp does not light during Steps 2 and
3 but does light when a jumper is connected to
ground, the warning light switch portion of the
combination valve is defective. Do not attempt to
disassemble the combination valve. If any portion
of the combination valve is defective, it must be
replaced with a new combination valve.
Testing Warning Light Switch {Vacuum)
1. Rev engine in park to charge booster.
NOTICE: Do not overspeed as serious engine
damage may result.
2. Turn off engine. Turn ignition switch to "ON"
position.
3. Depress brake pedal fully. Release and wait 60
seconds. Repeat if light does not come on.
4. Light should come on after 1-3 brake
applications.
5. If warning lamp does not light during step 3 but
does when a jumper connects the two switch
leads, the vacuum warning light switch is
inoperative. Replace vacuum warning light
switch.

 

Most of them things I been doing I forgot to say these are manuals brakes.

 

OH, you shoulda mentioned that.
Do a search on here in the brake section and see what comes up. I'm not sure now.