"Low brake fluid" warning on DIC every time
Thread Starter
Racer
Joined: Mar 2018
Posts: 456
Likes: 144
From: Frederick Colorado
"Low brake fluid" warning on DIC every time
I wrote in on this a long time back and did not get much help.
Every time I start the car, I get the indication on the DIC that the brake fluid is low. Of course, it's fine. I cleaned out the reservoir and the sensor was replaced by the used car dealer that sold me the car. The indication went away a couple of weeks and came back, so I cleaned the reservoir, fiddled with the floating magnet, which is floating all right, and I still have the indication.
Is the indication just stuck in the car's robotic mind? Do I just need some sort of extra special clearance from somebody with a Tech 2 to ignore it? I even turn it off with a cheapo bluetooth OBD2 reader and it never goes away.
Every time I start the car, I get the indication on the DIC that the brake fluid is low. Of course, it's fine. I cleaned out the reservoir and the sensor was replaced by the used car dealer that sold me the car. The indication went away a couple of weeks and came back, so I cleaned the reservoir, fiddled with the floating magnet, which is floating all right, and I still have the indication.
Is the indication just stuck in the car's robotic mind? Do I just need some sort of extra special clearance from somebody with a Tech 2 to ignore it? I even turn it off with a cheapo bluetooth OBD2 reader and it never goes away.
Last edited by FOGeologist; Apr 15, 2020 at 02:10 PM.
Drifting
Joined: Mar 2015
Posts: 1,421
Likes: 302
From: CSRA, SC
How many key cycles have you done? Some faults take 3 key cycles (on start/crank run off) without seeing the issue to stop showing you the issue. If you've done that, then you may have a wiring issue.
Thread Starter
Racer
Joined: Mar 2018
Posts: 456
Likes: 144
From: Frederick Colorado
I have disconnected the battery, etc. No dice.
Last edited by FOGeologist; Apr 15, 2020 at 03:10 PM.
Drifting
Joined: Mar 2015
Posts: 1,421
Likes: 302
From: CSRA, SC
I dug out my service manual for ya. Mine is a 2002 so this may vary depending on your year, but I bet it's the same regardless. The brake fluid level switch closes with low fluid. If the switch is working fine because it's new, and the IPC thinks the fluid level switch is closed because it is seeing ground at the connector pin, you must have a short to ground of the purple wire somewhere. With the key off, disconnect the brake level switch and use your multimeter to probe resistance from the pin of the purple wire to the frame, engine block, alternator frame or battery negative terminal. It should say open circuit. If there is some resistance you have a failed wire that is shorted to ground.
Racer
Joined: Jul 2019
Posts: 376
Likes: 116
From: MN
Looking at the shop manual diagram, it appears that both the Brake Level Switch and Parking Brake Switch both trigger the same indicator lamp. Are you actually getting a DTC on this, or just going by the indicator lamp? The Parking Brake Switch on my '02 is very sensitive and the slightest touch of the brake lever turns on the lamp.
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Thread Starter
Racer
Joined: Mar 2018
Posts: 456
Likes: 144
From: Frederick Colorado
Brilliant advice!
I dug out my service manual for ya. Mine is a 2002 so this may vary depending on your year, but I bet it's the same regardless. The brake fluid level switch closes with low fluid. If the switch is working fine because it's new, and the IPC thinks the fluid level switch is closed because it is seeing ground at the connector pin, you must have a short to ground of the purple wire somewhere. With the key off, disconnect the brake level switch and use your multimeter to probe resistance from the pin of the purple wire to the frame, engine block, alternator frame or battery negative terminal. It should say open circuit. If there is some resistance you have a failed wire that is shorted to ground.
Thread Starter
Racer
Joined: Mar 2018
Posts: 456
Likes: 144
From: Frederick Colorado
My reservoir is quite full. And the float is all the way at the top, away from the sensor. I think it's an open ground , as has been suggested.
Drifting
Joined: Mar 2015
Posts: 1,421
Likes: 302
From: CSRA, SC
Thanks I'm happy to help. I'm an electrical engineer in the off highway equipment industry so I've fixed my share of Gremlins usually on prototype stuff with a lot less documentation than this! Sucks to hear you have snow...let us know what you find
Thread Starter
Racer
Joined: Mar 2018
Posts: 456
Likes: 144
From: Frederick Colorado
Looking at the shop manual diagram, it appears that both the Brake Level Switch and Parking Brake Switch both trigger the same indicator lamp. Are you actually getting a DTC on this, or just going by the indicator lamp? The Parking Brake Switch on my '02 is very sensitive and the slightest touch of the brake lever turns on the lamp.
Pro
Joined: Apr 2017
Posts: 590
Likes: 134
From: Hanover Maryland
Thread Starter
Racer
Joined: Mar 2018
Posts: 456
Likes: 144
From: Frederick Colorado
Update
Update: a new twist
I have checked my reservoir, and found the magnet NOT FLOATING. i think this thing is intermittently floating and sinking, closing the connection and lighting up the DIC and the brake light.
I hauled up on the magnet with a bent pick, and it hung up... for a moment. Came back a couple of minutes later and found it on the floor of the reservoir.
Conclusion: I need a new reservoir. Damn thing IS nearly 24 years old. Think a new reservoir isn't too expensive on Rock Auto. Fluid needs changing anyway.
I have checked my reservoir, and found the magnet NOT FLOATING. i think this thing is intermittently floating and sinking, closing the connection and lighting up the DIC and the brake light.
I hauled up on the magnet with a bent pick, and it hung up... for a moment. Came back a couple of minutes later and found it on the floor of the reservoir.
Conclusion: I need a new reservoir. Damn thing IS nearly 24 years old. Think a new reservoir isn't too expensive on Rock Auto. Fluid needs changing anyway.
Last edited by FOGeologist; Apr 17, 2020 at 02:46 PM.
Thread Starter
Racer
Joined: Mar 2018
Posts: 456
Likes: 144
From: Frederick Colorado
A new AC Delco master is about $90. I can't say I'm eager to get inside the hydraulics on an ABS equipped vehicle, as a bleed job might be a pain in the neck. I could job it out to a local garage, but this may get kind of spendy.
Melting Slicks
Joined: Nov 1999
Posts: 2,347
Likes: 857
From: MI
Cruise-In VI Veteran
And have a look at the PDF I posted.
Cheers,
Goose
Thread Starter
Racer
Joined: Mar 2018
Posts: 456
Likes: 144
From: Frederick Colorado
Newest update
I determined that the reservoir I purchased from Rock Auto is really tall... probably too tall for the Vette. It's for a K1500, as the aftermarket and AC Delco reservoirs are no longer made for our C5 cars, I decided to change out the master cylinder.
I found an AC Delco Pro with reservoir for $68 on Amazon. Only drawback? Delivery date a month out
So I ordered it, and determined that I can bleed the brakes without much drama as I have a cooperative wife, great jack stands, and a Mity-Vac.
The posted Tech Guide by 69 was a blessing, too. Thanks!
I found an AC Delco Pro with reservoir for $68 on Amazon. Only drawback? Delivery date a month out
So I ordered it, and determined that I can bleed the brakes without much drama as I have a cooperative wife, great jack stands, and a Mity-Vac.
The posted Tech Guide by 69 was a blessing, too. Thanks!
Last edited by FOGeologist; Apr 18, 2020 at 01:00 PM.
Thread Starter
Racer
Joined: Mar 2018
Posts: 456
Likes: 144
From: Frederick Colorado
Master cylinder in...
And no change. I don't have any codes showing up on my cheap Bluetooth OBD 2 scanner. "Low Brake Fluid" pops up every key start, come hell or high water. I'm at 5 key cycles after a battery disconnect.
Well, I threw $70 at the problem and failed.
Now I think I'm looking for a closed circuit/broken wire/early ground or whatever.
Well, I threw $70 at the problem and failed.
Now I think I'm looking for a closed circuit/broken wire/early ground or whatever.