Low brake fluid message

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Jun 5, 2015 | 03:16 PM

#21

DWC4

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Joined: Mar 2006

Posts: 520

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From: Golden CO

$10, too good to be true

Quote:

Originally Posted by DWC4

Something I can fix on this car in under 10 minutes for under $10?? Hard to believe...

THANKS.

I knew it was too good to be true.. $11.19 cost. I guess I'll have to sell the car.

(thanks all!)

Advance Auto:
Brake Fluid Level Sensor
CARQUEST by BWD Brake Fluid Level Sensor
Part No: S8107
Warranty: LIMITED LIFETIME REPLACEMENT
Exact Fit for your 2003 Chevrolet Corvette

Jun 21, 2015 | 05:42 PM

#22

DWC4

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Joined: Mar 2006

Posts: 520

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From: Golden CO

Too good... a new sensor didn't fix it, next?

Put in the new sensor, still get the low fluid red light.

So there is another good thread about this I read here, and I know there's a magnet in the fluid reservoir that trips the (new) sensor. I'm hoping the problem is there. He cleaned his reservoir, removed gunk, and now it works.

https://www.corvetteforum.com/forums...d-warning.html

Do I have to bleed the brakes to pull that reservoir? Or actually, bleed them after I pull, clean and reinstall it?

If that's not it, what next? I'll see if the wiring diagram for this circuit helps me first, getting the meter out now..

.35 PPL wire, . ,BLK (ground) come to the switch. I'll see if I have power there. My hood light is also out, the bulb is good, no power at the plug... yikes could it be a fuse issue? Checking per diagram fuse block in engine bay.

Last edited by DWC4; Jun 21, 2015 at 05:52 PM. Reason: add link

Jun 22, 2015 | 07:06 AM

#23

dadaroo

Le Mans Master

Joined: Mar 2011

Posts: 6,835

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From: Columbia SC

Here is a link to the FSM info on replacing the reservoir. It says to remove the master cylinder. Not sure if you can do it on the car. My car is not here to see if there may be room. If you can do it on the car you may not need to bleed it.

https://www.dropbox.com/s/uvt1rr55j1...ement.pdf?dl=0

Jun 22, 2015 | 10:14 AM

#24

DWC4

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Joined: Mar 2006

Posts: 520

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From: Golden CO

low brake fluid sensor issue

Quote:

Originally Posted by dadaroo

Thank you! I got it and that helps some.

I think it's very possible that there is gunk keeping that reservoir magnet in a position that tells the sensor fluid is low. I drained the reservoir using a baster, sucked the fluid out; a lot of crap in there and the reservoir is lined with black goo. So, very possible also I have gunk in the lines.

I'm going to take it to a shop with Tech II and have it bled this time, since I don't know when it was done last (if ever!). Bought this '03 in 2013 with no maintenance history. Tech II works the ABS etc per another thread here and truly gets the old fluid out. After that if sensor is still bad, well, that's another day.

I did check ALL fuses and all look fine, I have no other issues except under hood light not working, oh and of course 'traction control' and 'active handling' issues I'm going to resolve 'real soon'.

Jun 22, 2015 | 11:35 AM

#25

dadaroo

Le Mans Master

Joined: Mar 2011

Posts: 6,835

Likes: 302

From: Columbia SC

Doing a Tech 2 automatic bleed is a good thing to flush out the ABS valves and fluid. I plan to do my car in the Fall since I bought a Tech 2 a while back.

Jun 24, 2015 | 09:06 AM

#26

DWC4

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Joined: Mar 2006

Posts: 520

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From: Golden CO

how to test brake fluid level sensor, make sense?

So there is a magnet in the reservoir that triggers that sensor switch - I assume the magnet is in some housing with air or something that makes it 'float' in brake fluid, and when the fluid gets low, that magnet is down low enough in the reservoir to trigger the switch and warning light.

I should remove the sensor from the reservoir and run the car with it plugged in, sitting upright away from the reservoir. In theory seems to me that would tell me if its the magnet stuck at the bottom of the reservoir OR, something else in that circuit. I put a new sensor in, that did not fix the problem. Doing this now.

RESULT: yep, the brake warning light disappears if I turn the car on with the sensor plugged in but not into the reservoir. It's that damn magnet in there, maybe not fixable??

Last edited by DWC4; Jun 24, 2015 at 10:30 AM. Reason: test worked

Jun 26, 2015 | 03:54 PM

#27

DWC4

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Joined: Mar 2006

Posts: 520

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From: Golden CO

How to fix stuck magnet in brake fluid reservoir

So I replaced the sensor, still got the warning light. If I remove sensor from the reservoir, plugged in, the warning goes away. So the problem is the sender - the magnet in the reservoir is stuck at the bottom, tripping the low brake fluid warning.

You can see that magnet with the cap and fluid removed, it rides in a vertical housing in the middle of the reservoir. With the fluid out, you might just see a 'black line' there but that's the slit where brake fluid goes in and floats that magnet away (up) from the sensor when there is adequate brake fluid. Mine was stuck in there due to really funky dirty fluid. Get a slender 6" or longer piece of metal that will reach in there and get in that vertical gap to clean it out, and then move the magnet up and down until it moves freely.

I did that, refilled brake fluid and, no more warning light.

Full flush/bleed of the system next week however, knowing how nasty that fluid has become.

Sep 25, 2018 | 08:51 AM

#28

DWC4

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Joined: Mar 2006

Posts: 520

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From: Golden CO

Quote:

Originally Posted by DWC4

So I replaced the sensor, still got the warning light. If I remove sensor from the reservoir, plugged in, the warning goes away. So the problem is the sender - the magnet in the reservoir is stuck at the bottom, tripping the low brake fluid warning.

You can see that magnet with the cap and fluid removed, it rides in a vertical housing in the middle of the reservoir. With the fluid out, you might just see a 'black line' there but that's the slit where brake fluid goes in and floats that magnet away (up) from the sensor when there is adequate brake fluid. Mine was stuck in there due to really funky dirty fluid. Get a slender 6" or longer piece of metal that will reach in there and get in that vertical gap to clean it out, and then move the magnet up and down until it moves freely. A FLATTENED (hammer it) piece of coat hanger works perfectly to get in there and 'exercise' the magnet a bit till it moves freely.

I did that, refilled brake fluid and, no more warning light.

Full flush/bleed of the system next week however, knowing how nasty that fluid has become.

This was 2015, it happened again Aug 2018, though I had a pro brake fluid flush and replacement done back then. This time when I drained the brake fluid (using a turkey baster, works great!) there was crud in there again though not as bad as last time. Once again used a narrow piece of wire to work the magnet free in that slot and after moving it around a lot, and cleaning out the one (right) side of the fluid housing I could get to, I topped it off with fresh fluid and no more warning light.