brake warning light and stabiltrak light on

[JerryIrons]

This started happening on me. 2006 EXT. ABS light never comes on. Plus the rapid chiming you can get if you put the emergency brake on while driving. What's really fun is that just going down the road, the lights can kind of intermittently go on and off, along with the chiming I've even had it happen just parked in the driveway. I made a video of that maybe I'll post it.

Lots of times though the stabiltrak and brake warning indicator, once they come on, will stay on. I pulled the brake fluid level sensor harness, no effect. Jumped it with a paperclip, no effect. I measure the voltage through the harness and it's 1.5 volts, doesn't sound right but I don't know what the proper voltage is, or if it's pulsed etc. Brakes work perfect, and fluid level spot on.

No ABS codes, and no check engine lights. In fact I cleared everything, and just putting the car into run without starting will trigger the 2 indicator lights and rapid chiming.

I'm about the change the ignition switch to rule that out. Anybody else with any thoughts have at it thanks. I played around with the parking brake switch near the lever but it seems ok. On the rare times the lights go out, I can pull up on the parking brake and the brake indicator light comes on and off correctly, with a little chiming. Also the brake lights come on correctly when the brake pedal is depressed, I checked those as well.

 

[Mooseman]

Very strange that the ABS light never comes on. Usually, when there is a fault with ABS, it will light with the Stabilitrak light. I can't think of a situation where the BRAKE light would light with the Stab light.

I do remember from way back with my old S10 Blazer where the ABS light came on and just pulled the bulb for it. Well, the BRAKE light came on instead because of the bulb. Does your ABS light come on during the bulb test?

Are you able to read other body/chassis codes? With the Stab light on, it should give a code.

 

[JerryIrons]

I have autoenginuity so will fire that up again to try and read things, it's not as good as a tech 2 but much better than lots of things, I can activate stuff.

Changed the ignition switch and still same problems.

 

[TollKeeper]

I am pretty sure it cant be checked with a standard scanner, it will require the uplevel scanner. One that can check ABS and SRS codes.

 

[JerryIrons]

I have an ABS scanner which can read things like bad wheel speed sensors. Plus my autoenginuity can do things like measure wheel speed, and activate the abs module, dump valves etc.

Here is a video link of me sitting in the driveway in park with engine running, about 45 seconds long. I rev the engine at one point to see if that affects it. This is the more erratic version, lots of times both lights are on steady. Yes there is a check engine light, but that has to do with P0017, which I have since cleared, along with ABS code clearing to make sure everything is clear. Same behavior put key to run, traction control blinks 6 times and brake light comes on. Start vehicle, same behavior and then usually both lights stay on.

 

[JerryIrons]

Does your ABS light come on during the bulb test?

Are you able to read other body/chassis codes? With the Stab light on, it should give a code.

I can talk to the instrument panel and do a bulb test, and yes the ABS light comes on during that test. Good idea though, I had not thought of that.

 

[JerryIrons]

Also it's not a case of turning off traction control. On the rare times things start acting normally, I can successfully turn traction control off and on, with the button on the side of the shifter, and the indicator light acts normal.

In looking at the brake warning schematic, the only thing that can turn that light on is the parking brake switch or the brake fluid level switch. Can you tell I'm thinking out loud now?

Are you guys able to talk to the EBCM module in your tech 2? (electronic brake control module)

 

[JerryIrons]

I think I got it fixed. Wondered where the EBCM module was, and saw that it's attached to the ABS valve under the car under the driver door. Saw that big connector and unseated it, kind of cleaned it out, and reseated it. Took it for a test drive and thought it was fixed at first, but then the same thing happened. Only not as much so I knew I was close. Drove home and this time unseated it, cleaned it out (although it really wasn't that dirty), put some silicon dielectric grease along the male end, and plugged it back up. Also decided to clean up that engine ground right there on the frame. Of course that bolt was so corroded I needed to get the hot wrench out and heat up both sides red hot. (I had replaced it years ago with a bolt and nut). Used the dremel wire brush to clean off the frame, and put a new bolt, nut and washers there. This was especially fun doing it in my driveway in 40 degree weather with rain coming down pretty heavily

That all being said, went for a test drive, gassed it up, half a dozen stop and starts and everything good. If it happens again, I might be dealing with a bad EBCM. Apparently those things like to have solder connections inside go bad but I am crossing my fingers so far so good. Thanks to those who replied with help, I really appreciate it.

 

[Mooseman]

After looking at the video, I was just gonna say that it's a ground or wiring issue.

 

[TequilaWarrior]

After looking at the video, I was just gonna say that it's a ground or wiring issue.

Probably this....

but dang if that doesn't remind me of the old ALDL and engine light blinking out codes in my Cutlass....

 

[JerryIrons]

Well this thing has reared it's ugly head again, same problem as before. I will check the ground connection but pretty sure that's not the problem. What I will do is just set up a jumper wire to a good ground and see if that makes all the beeping quiet down

The good news, I snagged one of those vxdiag connectors, that comes with tech2win software and it's working good for me. I may post a how to do that, it was a little tricky to install and configure but I'm talking to all the systems on the car now, and can finally update software on the modules and do an ABS bleed without having to drive it and slam on the brakes lol. Pulled a couple of C codes, one had to do with yaw sensor and another with torque but will start with the ground first. Last time I was able to wiggle the connector going into the ebcm to make things better.

Anyway, will post here tracking my progress.

 

[JerryIrons]

Put the vehicle in my garage, and set up a test ground wire running from the ground on the frame near the EBCM right to the negative battery post and no change. Wiggled the heck out of the connector and wires going into the ebcm, no change. After reseating the connector a few times, and tapping on the ebcm/pump lightly with a hammer to try and cause the solder joints to connect, I got the lights to go out, but that didn't even last a mile down the road before it came back on.

No trouble codes, not even any ABS codes. In fact, I can clear the codes, and then immediately after I get the same red brake indicator light comes on, along with traction control disabled. Went for a test drive tonight, and watched all 4 wheel speed sensors give accurate readings. I can talk to the EBCM via diagnostic software ok, but with autoenginuity I'm seeing negative voltage on the yaw sensor which is out of range. At some point I will fire up by tech2 clone and see what else I can find. The EBCM is definitely sending a signal to the main computer to illuminate the red brake light.

Service manual states that if the traction control light is always on, replace EBCM. (or fix the solder joints I guess)

I did snag a ebcm/abs pump from a junk yard. Started removing the ebcm from the junk yard pull, got the two top screws out ok, but bottom ones were so corroded I ended up grinding off the top of those screws and drilled a bit to pull the EBCM off. I still have to drill out the 2 bottom screws in the abs pump portion, they were completely corroded/galvanized in place. (once I got the EBCM off I tried using vice grips on the bolts that were sticking out but all that did was twist and break the bolt). My existing installed ebcm/pump screws are even more corroded than the junk yard pull. The abs pump bracket bolts are so rusty I will be extremely surprised if I don't break any of them if I elect to replace both ebcm/abs pump. So either way this is not going to be fun. But at least I will be able to use my favorite tool, the hot wrench

According to the service manual, there are only 4 ways for the red brake light indicator to come on:
1) parking brake engaged. (this works fine I tested it out)
2) low brake fluid or base brake pressure differential (up on the master cylinder, a difference in pressure between the front and back systems)
note a bad brake fluid switch can cause this, but I removed that switch and jumped it to test.
3) IPC bulb check
4) EBCM detects an ABS disabling malfunction which also disables dynamic rear proportioning.
Curious thing is my ABS works fine, I tested it out in the snow the other day, while both traction control lights and red brake light illuminated.

I think I will try putting the junk yard pull back together enough to test, and just plug in to my vehicle's connector without actually installing it, and see what happens. I'm leaning toward a bad EBCM, but really do not want to replace it and see the same problems happen, this is not going to be an easy job.