Dash lights

[Sparky]

What is the purpose of the brake check light switch in the dash. I push it and does not light up. is there a replacable bulb? Also is there a replaceable bulb in the rocker switches, such as hazard sw. in radio console. This is in a 74 gt.

Thank you /ubbthreads/images/graemlins/driving.gif

 

[NC Mike]

[ QUOTE ]
What is the purpose of the brake check light switch in the dash. I push it and does not light up. is there a replacable bulb? Also is there a replaceable bulb in the rocker switches, such as hazard sw. in radio console. This is in a 74 gt.

[/ QUOTE ]

Hi Sparky,

Having recently rebuilt a 74.5 dash, I'm fairly confident with my info, hope it helps.

Easy question first - Yes, there are replacable lights for the rocker switches. The "retaining clip" behind each switch is a plastic frame with two small pieces on each long side that fit in corresponding openings on the switch body and hold the switch in place. The top part of the retaining clip is a circular opening that holds the light bulb used to illuminate the switch.

A slight twisting motion while holding the metal base of the bulb socket is usually sufficient for the socket and bulb to come free from the retaining clip. Push the bulb in and twist about one-half turn to remove it from the base. The light sockets are wired with either a white with red trace or red with white trace positive wire ( I don't remember which), and a black ground wire.


The light in the brake check light switch, if memory serves correctly, will light up when pushed if the lights in the brake circuit are good (assuming the bulb in that switch is good) /ubbthreads/images/graemlins/smile.gif Sort of works as a test light for the brake light system.

That bulb is also replaceable. Carefully removing the red lens should give access to the screw-in type bulb. Unscrew in the anti or counter-clockwise direction.

The lens is U-shaped, so to speak, with slight projections on the outside, bottom edges providing a friction fit of sorts and tend to break easily (at least with me), so a gentle touch may be in order.


Take your time,

Mike /ubbthreads/images/graemlins/patriot.gif

 

[Bugeye58]

The brake test switch tests whether both front and rear brake hydraulic circuits are operating. If one of the circuits fail, the differential pressure in the brake system will trigger the brake pressure failure switch, and illuminate the red light in the dash . The switch is built with a "press to test" function so you know the bulb is good to avoid sudden surprises. If the light comes on while driving, you'd better be stopping somewhere soon, because chances are you have just developed a major leak, causing one side of the brake reservoir to empty.
Jeff

 

[Bruce74B]

I think this is one of those good ideas that went bad and has never really worked on most cars, but got the Government off the backs of BLC. The test light should work (and usually does) when pressed on, but I have yet to see the light actually come on when the hydraulics are unbalanced in any of the MGBs I have driven. I recently changed the front brake hoses and bled the system and at NO time did that light come on. I didn't get the one hose tight enough and had a major leak and drove the car for a few miles,including some hard brakings (enough to lock up the rear wheel once) and that silly light never did come on.

I say replace the bulb and let it go, but inspect your resevoir and lines frequently. I may have a spare bulb for you if you can't find one...if I ever get around to swapping my switch with a broken cover with one I bought last year...hard to get my big hands back there in that corner /ubbthreads/images/graemlins/frown.gif

Bruce /ubbthreads/images/graemlins/cheers.gif

 

[Sparky]

Thanks guys! Great answers. Will work on tonight

/ubbthreads/images/graemlins/cheers.gif

 

[Bugeye58]

Bruce, kind of like the light on the dash with some of the cannister oil filters to let you know it was bypassing!
I just took the '72 out today, and pressed the test funtion on the brake switch, and the light didn't work! So, it looks as though I need to change the bulb. Mine did work when I flushed and bled the brakes last year.
Jeff
Just went to change the bulb, and when I wiggled the old bulb in the socket, it started working again. Hmmm. Lucas and a bad contact? How strange is that ?
J