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master cylinder harness
Posted: Sat Feb 21, 2015 7:58 pm
by unclebubbaSE
Hey everyone, don't like to repeat posts, but I couldn't find anything specific about my issue...I found the harness that plugs into the brake master cylinder to be disconnected, just hanging below. When I plugged the harness connector back into the master cylinder, the "brake" light on the cluster will come on and stay on solid after engine starts and while driving. It of course will usually go out when the e-brake is released, but now will not. I guess I know now why it was disconnected!. Is this the abs harness, or a level sensor harness?. Why would the light be on when plugged in as normal?.
The brake fluid is at proper level, and the light went off when I re-disconnected it.
Thanks in advance for any thoughts, info!.
Re: master cylinder harness
Posted: Sun Feb 22, 2015 7:42 pm
by SkiBonne
If that light goes on with the sensor connected, there is usually a problem. If there is no other issue with the brakes, there could be an problem with the sensor itself. How does the vehicle brake? Does it stop normally?
Re: master cylinder harness
Posted: Sun Feb 22, 2015 10:45 pm
by nos4blood70
That is a level sensor. Might be a bad sensor, hence why someone unplugged it in the past.
Re: master cylinder harness
Posted: Sun Feb 22, 2015 10:47 pm
by haro1225
That would be the fluid level sensor. Shouldn't have anything to do with the abs. Just keep an eye on the fluid to make sure there is enough in there.
EDIT: what Carl said ^^
Re: master cylinder harness
Posted: Sun Feb 22, 2015 11:41 pm
by harofreak00
There is a problem with the sensor. Someone disconnected the wiring so it doesn't display the BRAKE light all the time. The sensor itself is really cheap brand new, like $10. Try replacing it first. If that doesn't fix it, you'll need to remove the reservoir and clean it out. There is buildup inside that causes the float not to move. (The actual sensor doesn't even touch the fluid) In my experience, you'll likely run into the dirty reservoir before the bad sensor.

Re: master cylinder harness
Posted: Sun Feb 22, 2015 11:58 pm
by unclebubbaSE
Yea, the vehicle brakes perfectly, no worries there. If it is a bad level sensor itself, would I have to remove the master cyl. assy. to replace it?....if that's the case, I'll leave the sensor harness unplugged and check the fluid level regularly, rather than have to remove the freakin' master cylinder just to get things "proper"!.
Thanks for the feedback guys!
Cheers
Re: master cylinder harness
Posted: Mon Feb 23, 2015 1:03 am
by harofreak00
No, the sensor is very easy to replace, it just pulls straight out. See video:
https://www.youtube.com/watch?v=RqHETudnbNo
Re: master cylinder harness
Posted: Tue Feb 24, 2015 12:38 am
by unclebubbaSE
Great video link...I can't believe it would be that easy. I'll order mine today from rock auto for $3.48 plus shipping!.
Re: master cylinder harness
Posted: Sun Mar 01, 2015 3:49 am
by unclebubbaSE
Well...I replaced the fluid level sensor in the master cyl. today, reconnected the harness and the *dang* light is still on!.
Brake fluid was strange color, almost a dark "moss" green, as opposed the the usual darker brown color. I'm probably going to have brake flush performed just to get fresh dot 3 in there and see what happens. If the flush doesn't solve the problem, I'm just going to unplug the freakin' harness and forget about it.
The car brakes fine, that's all I'm concerned with at this point.
Cheers!.
Re: master cylinder harness
Posted: Mon Mar 02, 2015 9:53 am
by harofreak00
If you have a shop do the flush, you'll have to specifically ask for the reservoir to be cleaned out. They will need to remove it from the master cylinder (a couple pins that pull out) and then use some cleaning solvent inside the reservoir and slosh it around.