That silly, Brake light is stuck on or flashing.                    

This one problem that  will drive some people, very crazy, because the lamp is really has 4 different functions!

If the lamp sticks on , follow my list below  to discover the reason.  (easy to hard).

This is a giant 4 level LOGICAL "OR" gate.   (also called wired "OR" by technicians)

A or B or C or D = Lamp.

First chock the front and rear of one back wheel.  Be parked on flat ground. (Safety).

The first check, is to turn off the parking brake,  release it and see if the lamp goes out.
Leaving the parking brake released , we then , pop the hood and remove cap to the brake master cylinder, is it full to the line?
No, then fill it.
Is brake fluid level full now ? and is the lamp still stuck on? 
Yes,  then ,  then unplug the wire plug at the Mastercylinder level gauge switch.
Did the lamp go out, yes, then the switch is bad.
Still on  that Brake lamp, if switch was good, then proceed to next line.  ( proceed if unplugging this switch does not make lamp go out)
See the pressure differential valve , and the plug wire to it.  PART 30 is the switch sensor. see red marks below?
See yellowish plug in center , here?

Remove it ,this Diff. plug ,does the lamp go out, yes, then you must follow the shop manual procedure to adjust it or to find the reason that your brakes are unbalanced.  This switch will glow the Dash lamp regardless of the RWAL computer (controller) . Just about every car has this switch.
After servicing brakes, STOMPing, the brake pedal REALLY HARD, can in fact re-center this switch and make the sensor happy.  100lbs of force or more!

The lamp stays on , yes! with this plug unplugged and all the others stated above , this means the RWAL controller is reporting a fault.

See my next link for how to trouble shoot the RWAL.


unplug  the RWAL controller plug , the lamp must go out ( see back large box mounted to fire wall just above left toes.)

if the lamp does not go out , you must remove the center console and unplug the hand brake connector.
If the hand brake connector does not clear the fault, then the cars wiring harness is bad or the dash lamp input wire is shorted to the body.
If this action does clear the fault then the hand brake switch is bad.


Removing the RWAL CONNECTOR caused the brake lamp to go out. ( oops, RWAL is unhappy)

You must download this manual link I found , to place a jumper and get the RWAL Puter to flash out the codes.
These codes will tell you, what it thinks is wrong.  This RWAL unit has  a tiny microprocessor brain and ROM code.  Just like the ECU but vastly dumber.

Suzuki RWAL  flow charts.  

In the Factory manuals the flow cart B , is faulty. This B page is for a loss of power or a bad RWAL controller.

There are 11 codes.
code  what the RWAL puter thinks is wrong. (it's usually right)
Open Isolation Solenoid
Open Dump vlave solenoid circuit.  coil open ,wires cut.
Valve reset switch closed and shouldnt be.
System dumps too many times. Occurs while braking, only.
Rear wheel speed sensor changed too rapidly , only driving.
Shorted Isolation sokenoid circuit.
Shorted Dump Solenoid circuit.
Open rear wheel sensor circuit. 
Stop light switch remains on.  Stuck !
Shorted rear wheel sensor circuit.
RWAL control module malfunction.  " I am crazy  RWAL puter" crash !

Notice missing code 12?  This code was forgotten during Japanese coffee break.  LOL !
It has no code for OK, it simply turns out the Brake lamp, if RWAL puter, is ok and happy.

The jumper wire is placed between pins 3 to 5 the RWAL DLC  diag. connector mounted to the steering shaft.
Key on, and jumper or just 2 seconds and the codes will flash out.

I have no troubleshooting here, just how to get to the fault codes.
See the above DOWNLOAD link for the flow charts.

FYI: Diagnostic Jumper, 5 to 10 for TCM  automatic transmission 4speed, error  codes.  (not related to RWAL , this is just hint)

ver4 added  flow charts