Birty Dastards Jeep Club

Tech Forum => Workshop => Topic started by: Paulie on August 04, 2013, 08:21:47 PM

Title: Brake warning light
Post by: Paulie on August 04, 2013, 08:21:47 PM
I had a brake pipe pop on the TJ last week whilst braking hard to avoid a stray dog. Obviously the light came on and I limped home. I've changed the pipe and bled the system and everything is working fine, in fact better than before with a bleed and some fresh fluid. Only trouble is that the warning light will not extinguish. Will it go out on it's own or do I have some more work to do?
Title: Re: Brake warning light
Post by: MOCAJ on August 04, 2013, 08:29:00 PM
try disconnecting the battery, make sure you have radio code if needed
Title: Re: Brake warning light
Post by: isle of man on August 04, 2013, 08:35:24 PM
Sensor by the master cylinder FUBAR...
Title: Re: Brake warning light
Post by: Jonny Jeep on August 05, 2013, 06:24:18 PM
I've sure I've seen mrblaine post on jeepforum about this happening and telling people to stomp hard on the brake pedal several times to get the valve to reset.
Title: Re: Brake warning light
Post by: Paulie on August 11, 2013, 11:31:23 AM
Thanks for the replies guys.For some reason I'm no longer getting notifications of responses on my subscribed threads and I didn't realise any one had answered this query.
The warning light seemed to be working fine until the brake fluid level dropped significantly in the master cylinder at which point it stayed on, so I think all the component parts are in good working order. I'll give it the stomp test later, then try the battery fix. Hopefully I wont have to spring for a new switch assembly. According to the Haynes book of lies it is part of the combination valve and sounds jolly expensive.
Title: Re: Brake warning light
Post by: Mike Pavelin on August 11, 2013, 01:56:55 PM
The light is operated by a shuttle in the dual circuit master cylinder. Pressure from each hydraulic circuit is applied to either end of this, so it will not move unless there is a significant drop in pressure on one or the other, like when your hose failed. To reset it, crack off a bleed nipple in the circuit that didn't fail and press the brake to move the shuttle back and put out the light.
Title: Re: Brake warning light
Post by: Paulie on August 11, 2013, 07:34:51 PM
That sounds feasible. I've tried stomping the pedal, Haynes says you have to surpass 450psi. How you are supposed to know when that is God only knows. If it's just a switch then I don't suppose disconnecting the battery will help.
Title: Re: Brake warning light
Post by: bgbazz on August 11, 2013, 09:06:26 PM
Strange beasts, these Jeeps..I've cleared quite a few warning lights (never to re-appear) with the battery trick.
It's worth a try.
Title: Re: Brake warning light
Post by: Paulie on August 19, 2013, 08:22:47 AM
 Well, I got a chance yesterday to have a look at this little issue. It would seem that nipple cracking is where it's at. Opened a front brake, gave it a few pumps and hey presto, light goes out. Thanks for all the suggestions chaps.