Calgary Jeep Association

Author Topic: JK Brake Warning Light  (Read 84 times)

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Offline Rubi55

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JK Brake Warning Light
« on: August 15, 2020, 10:44:38 AM »
Looking for some advice on this as it has hit the point now where the dash boards an xmas tree.  About 2 years ago, started to notice when the jeep was cold (and when the weather was cold) i could push the brake pedal down to a point and get a very loud whistle noise from the master cylinder brake booster area.  Nothing to do with the physical brakes themselves as this would be at a stand still.  Thought nothing really of it as my brakes were working just fine.  Pedal would eventually get squishy, bleed the brakes and I'd always have a fair amount of air in the lines.  No leaks though and the master was never low. Now 3 weeks ago, brake light comes on the dash, brake performance hasnt changed and I haven't had the whistle because it's not cold out.  I'm thinking it has to be related to that whistle though... vacuum line or the booster is shot??  Stuck on this one as I haven't had a chance to scan it.

On top of this, abs and traction control lights have been on (got tired of it going on and off so just pulled that fuse over a year ago), but when the brake light came on I put the fuse back in and the lights stayed on.  Abs doesnt work, cruise control doesnt work so Im thinking this is a wheel speed sensor issue and not the abs module.  Will be swapping out the front hubs anyways as they are due, and the rear sensors I replaced last year. 

Is the brake light being on tied to my abs system not functioning due to speed sensors not working or is this an issue with air trapped in the abs manifold or the abs module being toast, mc/booster gone bad, or something else all together?

Any help would be great.
'11 JKU Rubicon

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Re: JK Brake Warning Light
« Reply #1 on: August 15, 2020, 11:18:28 AM »
It always seemed like JK’s have a soft or spongey brake pedal feel.
If you have a brake light on first check and make sure your fluid level is ok.
After that it needs a scan to confirm what is causing each light to be on. Could be a wheel sensor or even a clock spring issue.
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Offline MattMan

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Re: JK Brake Warning Light
« Reply #2 on: August 15, 2020, 07:08:06 PM »
As far as the brake light coming on sporadically it has happened to me on occasion and each time it’s been a matter of cleaning the brakes of debris and getting them lubed back up and the light went out afterwards.
I just resolved the stabili-track and ABS light being on on my jeep and it was a result of the wheel speed sensor being faulty. I just replace the hubs in January and one of the sensors failed so luckily I was able to have it warranted. It’s nice not to have the dash it up like a Christmas tree anymore.  ;)


I just purchased a FIXD Bluetooth diagnostic tester ($75) that was able to tell me exactly which wheel speed sensor was faulty. If you want to get together and test out yours PM me.
MattMan

'12 JK Sport, 5spd ATS auto, P285/70r17 Duratracs on 17x9 Trailmaster steelies, 3" coil-lifted, "DV8" bumpers, Smitty rock rails, K&N w/Magna-flow exh, TrailDash 2’ner, CB, no lockers, Warn VR10, carbon fibre cowl hood, MOAB rating: “billygoat”

Offline Rubi55

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Re: JK Brake Warning Light
« Reply #3 on: August 20, 2020, 10:47:49 AM »
Quick update, should anyone else have this happen.  My airbag light came on as well.  Had read a lot about the clock spring failing, so I bought a proper scanner to get all the codes.  Codes just read bad wheel speed sensors at both fronts and an error with the clock spring.  Looks like bad wheel speed sensors and a clock spring will throw on the check brake system light?  According to one of the guyss at Varsity chrysler it does happen.   Have new hubs landing this week and picking up a new clock spring tonight.  After everything is replaced we'll see if the xmas tree is no more!
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Re: JK Brake Warning Light
« Reply #4 on: August 20, 2020, 04:58:16 PM »
Quick update, should anyone else have this happen.  My airbag light came on as well.  Had read a lot about the clock spring failing, so I bought a proper scanner to get all the codes.  Codes just read bad wheel speed sensors at both fronts and an error with the clock spring.  Looks like bad wheel speed sensors and a clock spring will throw on the check brake system light?  According to one of the guyss at Varsity chrysler it does happen.   Have new hubs landing this week and picking up a new clock spring tonight.  After everything is replaced we'll see if the xmas tree is no more!
Might want to confirm with your dealer but I believe some JK’s had extended warranty on clock springs.
YJ=Y’all Jealous