Low brake fluid message
Thread Starter
Advanced
Joined: Nov 2007
Posts: 84
Likes: 1
From: San Juan Puerto Rico
Low brake fluid message
I'm getting a "low brake fluid" message on my '98 C5. I checked the brake fluid reservoir and it's full. Brakes are spongy and sometimes the brake pedal drops almost to the floor then goes back to normal. I changed the sender with no different results.
Any ideas with this problem?
Any ideas with this problem?
Last edited by TropicalVette; Mar 24, 2015 at 09:13 AM. Reason: No response
Thread Starter
Advanced
Joined: Nov 2007
Posts: 84
Likes: 1
From: San Juan Puerto Rico
Thank you for taking some time to help...
This Vette has been worked on for the past four years. It was sitting on tower jacks for almost two years. When we finally got it done it started showing the brake problems, mostly the "low brake fluid" message. Before the accident that put it out of commission I had installed steel brake lines that worked great. When I installed them we bled the system and all was good.
Just when we finished setting up and getting ready for the dyno that message started showing, and few other bugs that I will get to next, after I fix the brakes.
I have been suspecting the master cylinder but since these cars tend to have gremlins living on board strange things happen every once in a while and I wanted to see if there could be another cause.
Le Mans Master
Joined: Mar 2011
Posts: 6,835
Likes: 302
From: Columbia SC
If you did brake work, check the calipers. More than one person on the Forum here installed calipers upside down so the bleed screw was not at the top.
If that is not an issue it seems like your maser cylinder is your issue.
Is it possible you got air into the ABS unit? It is hard to remove without using a Tech 2 to do a power bleed with the ABS pump.
If that is not an issue it seems like your maser cylinder is your issue.
Is it possible you got air into the ABS unit? It is hard to remove without using a Tech 2 to do a power bleed with the ABS pump.
Thread Starter
Advanced
Joined: Nov 2007
Posts: 84
Likes: 1
From: San Juan Puerto Rico
If you did brake work, check the calipers. More than one person on the Forum here installed calipers upside down so the bleed screw was not at the top.
If that is not an issue it seems like your maser cylinder is your issue.
Is it possible you got air into the ABS unit? It is hard to remove without using a Tech 2 to do a power bleed with the ABS pump.
If that is not an issue it seems like your maser cylinder is your issue.
Is it possible you got air into the ABS unit? It is hard to remove without using a Tech 2 to do a power bleed with the ABS pump.
Le Mans Master
Joined: Mar 2011
Posts: 6,835
Likes: 302
From: Columbia SC
No, it is the special GM scanner. In your area probably only a dealer would have one or a shop that specializes in GM products.
Check the calipers first.
Still most likely a master cylinder in my mind.
Check the calipers first.
Still most likely a master cylinder in my mind.
Thread Starter
Advanced
Joined: Nov 2007
Posts: 84
Likes: 1
From: San Juan Puerto Rico
So, I installed a new master cylinder after bench top bleeding it and then bled all four wheels. Stops on a dime, the only problem now is that the "low break fluid" message won't go away. Do you know how to turn it off?
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Le Mans Master
Joined: Feb 2012
Posts: 6,644
Likes: 479
From: OK
That's just tooooooo simple. Can't you post a schematic of the switch and make this super complicated... test pin #4, should be X amps, then whirl around on your left foot 2 times and do a back flip... stand on your head and redo all the grounds on your car....jumper wire from starter to brake sensor and run a ground to the tail lights...Heck do something ... it's too simple 
Le Mans Master
Joined: Feb 2012
Posts: 6,644
Likes: 479
From: OK
lol... thanks Sam 
I'll copy and paste that in my C5 files...
By the way... I think my Moral Rectifier may be bad... can I get a new one somewhere?
I'll copy and paste that in my C5 files...
By the way... I think my Moral Rectifier may be bad... can I get a new one somewhere?
Last edited by 73Corvette; Apr 24, 2015 at 08:49 AM.
Pro
Joined: Mar 2006
Posts: 521
Likes: 23
From: Golden CO
that schematic seems accurate
That is crazy funny, thanks, made my day.
- and that's some good advice, I have the 'low brake fluid' message also and it's topped off so I will check the switch, then master cylinder (not sure how...but I'll look it up) then if no help there, ugh, take it to dealer for Tech 2.
THANKS
- and that's some good advice, I have the 'low brake fluid' message also and it's topped off so I will check the switch, then master cylinder (not sure how...but I'll look it up) then if no help there, ugh, take it to dealer for Tech 2.
THANKS
Pro
Joined: Mar 2006
Posts: 521
Likes: 23
From: Golden CO
low brake fluid msg goes away when I unplug from the sender
'03, yep, when I unplug it the light goes out so, a bad or stuck switch in there. Any tips on the next step, can this be fixed without draining the fluid, etc etc? I mean, I realize I'll have to get down in there some but can I just remove enough fluid to be able to get to that unit then top it off again? Thanks.
Pro
Joined: Mar 2006
Posts: 521
Likes: 23
From: Golden CO
Le Mans Master
Joined: Mar 2011
Posts: 6,835
Likes: 302
From: Columbia SC
The FSM does not require lowering the brake fluid level. It does require you to use needle nose tip pliers to release the retention tabs. These are on the opposite side from the switch electrical connector.
