Bad Brake Switch, low brake fluid or something else?

Mike Fisher · February 27, 2020

Got in my 2009 Silverado 1500 this morning and turned it on only to be met with Stabilitrack Off, Traction Control Off and Service Brake System messages. I did some googling and found other posts here. The first guy solved his by adding more brake fluid, but a poster advised you shouldn't need to add brake fluid, its low due to worn brakes or a leak(which won't be fixed just by adding more fluid). My brakes are past due for replacement, I was holding out till next month as I just made my last payment on the truck this month so will have more free money next week.

Other things I found that could be the cause is a faulty brake switch. Others mentioned their cruise control not working so I checked and mine is also not working. So I am leaning towards this as the issue, but it doesn't appear to be affecting my brakes lights(although I read it could be intermittent). I can only test them when parked in my garage, but they come on every time I press the brakes and turn off when I release the brake.

It looks like the brake switch is fairly cheap and easy to replace, so should I just go ahead and replace it and see if it fixes the issue? I know I still need to get my brakes replaced, but if the worn brakes aren't causing the problem, then I think I'm good to wait till next month on getting those replaced. Otherwise if I do get the brakes replaced now should I just have them swap the switch for me too or still do that myself? I'm far from a mechanic, but thanks to google/youtube have been able to do the occasional minor fix myself. Thanks!

tlaw91 · February 27, 2020

Dtcs?

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Mike Fisher · February 27, 2020

1 hour ago, tlaw91 said:

Dtcs?

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No codes being pulled by my reader. I went ahead and replaced the brake switch but the errors remain. Was beginning to wonder if I had a bad(new) switch, since that seemed to be the fix for so many others. I decided to take the truck for a spin around the block to see if maybe it was an error that would go away after a short time of driving. No such luck there, but after parking and walking around the truck to head inside I noticed a leak of some kind by my passenger side rear wheel. Took a look and it definitely looks like I have a leak coming from that wheel. I'm assuming its brake fluid leaking from the drum brake, make sense? Would that cause these other errors and the cruise control to not work?

tlaw91 · February 27, 2020

You need a better scanner. You have dtcs. Otherwise you’re just shooting in the dark. And no, that leak is from an axle seal not a brake leak.

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MaverickZ71 · February 27, 2020

The brake light switch going bad is a common problem and will cause your cruise control to not work, but that will throw a trouble code. I got a replacement AC Delco brake light switch at OReilly Auto Parts for like $20 to install myself.

I have also had the disappearing brake fluid in our '09, and that will throw those warnings due to low brake fluid when the levels gets below half full in the master cylinder. Still sorting out the disappearing brake fluid. I don't take it to the GM dealer and leave them a blank check to fix it, due to expensive health issues. Brakes work fine, even at 1/2 full; no visible leaks anywhere. Truck eats about a 12 oz bottle of brake fluid every 10 months. It has done that for the last 2.5 years and hasn't gotten any worse, even in town where I have to stand on the brakes once in a while when some igmo pulls out in front of us. (Hello, how can you not see the 5300 pound white truck with the daytime running lights????) I've been told it may possibly be a bad seal in the bottom of the master cylinder, which is very slowly leaking brake fluid into the brake booster, which is periodically sucking brake fluid into the engine, where it is being burned off. In which case I'll need a new master cylinder, brake booster, and new brake fluid fill and bleed with ABS reset. OUCH.

tlaw91 · February 28, 2020

The brake light switch going bad is a common problem and will cause your cruise control to not work, but that will throw a trouble code. I got a replacement AC Delco brake light switch at OReilly Auto Parts for like $20 to install myself.

I have also had the disappearing brake fluid in our '09, and that will throw those warnings due to low brake fluid when the levels gets below half full in the master cylinder. Still sorting out the disappearing brake fluid. I don't take it to the GM dealer and leave them a blank check to fix it, due to expensive health issues. Brakes work fine, even at 1/2 full; no visible leaks anywhere. Truck eats about a 12 oz bottle of brake fluid every 10 months. It has done that for the last 2.5 years and hasn't gotten any worse, even in town where I have to stand on the brakes once in a while when some igmo pulls out in front of us. (Hello, how can you not see the 5300 pound white truck with the daytime running lights????) I've been told it may possibly be a bad seal in the bottom of the master cylinder, which is very slowly leaking brake fluid into the brake booster, which is periodically sucking brake fluid into the engine, where it is being burned off. In which case I'll need a new master cylinder, brake booster, and new brake fluid fill and bleed with ABS reset. OUCH.

That’s an easy diagnostic! Take off the vacuum hose going to the booster and stick a zip tie down in there. If it’s wet, it’s bad.

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Mike Fisher · February 28, 2020

15 hours ago, MaverickZ71 said:

The brake light switch going bad is a common problem and will cause your cruise control to not work, but that will throw a trouble code. I got a replacement AC Delco brake light switch at OReilly Auto Parts for like $20 to install myself.

I have also had the disappearing brake fluid in our '09, and that will throw those warnings due to low brake fluid when the levels gets below half full in the master cylinder. Still sorting out the disappearing brake fluid. I don't take it to the GM dealer and leave them a blank check to fix it, due to expensive health issues. Brakes work fine, even at 1/2 full; no visible leaks anywhere. Truck eats about a 12 oz bottle of brake fluid every 10 months. It has done that for the last 2.5 years and hasn't gotten any worse, even in town where I have to stand on the brakes once in a while when some igmo pulls out in front of us. (Hello, how can you not see the 5300 pound white truck with the daytime running lights????) I've been told it may possibly be a bad seal in the bottom of the master cylinder, which is very slowly leaking brake fluid into the brake booster, which is periodically sucking brake fluid into the engine, where it is being burned off. In which case I'll need a new master cylinder, brake booster, and new brake fluid fill and bleed with ABS reset. OUCH.

I don't think mine has been disappearing much. Well I figured it was just low due to the Brakes needing replaced. But that was when it was just barely(like right at the bottom edge of it) below min. Now its maybe an 1/8" lower than that. Which i attributed to the leak from the rear wheel, but tlaw said thats an axle seal leak.

But I'm not mechanic and my code reader isn't good enough so it's going to the shop. Fingers crossed its something simple like the brakes needing replaced, but obviously the leak is concerning.

tlaw91 · February 28, 2020

I don't think mine has been disappearing much. Well I figured it was just low due to the Brakes needing replaced. But that was when it was just barely(like right at the bottom edge of it) below min. Now its maybe an 1/8" lower than that. Which i attributed to the leak from the rear wheel, but tlaw said thats an axle seal leak.

But I'm not mechanic and my code reader isn't good enough so it's going to the shop. Fingers crossed its something simple like the brakes needing replaced, but obviously the leak is concerning.

If it is a rear brake leak that would be very unusual for sure.

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Area51 · February 29, 2020

When GM built these trucks, they put a plug on the front side of the motor, towards the bottom, and it brings all the stabilitrac, traction control, and abs stuff through it. It's there in case the motor needs removed. It may be worth crawling under there and checking it too since it's somewhat exposed.