2007 Yukon Denali - Brake - Traction Control warning lamps

[Doubeleive]

also brake fluid should not be "low" check all 4 corners for any signs of a leak or if the brake pads are nearly worn out that could be a reason for low fluid also, if you filled it and there is no leaks and you go to do the pads later keep a big rag under the reservoir because it will spill out when you press the caliper back for new pads.

 

[Fless]

Yeah, I fully expected a faulty wheel speed sensor. That would have been a straight forward fix. But it appears they are good.

I did check the history but the only code in history was for low brake fluid. Fluid level is ok. I ignored that record. I will check everything again today but I think the wheel speed sensors are pretty much ruled out.

The Tech2 is complicated. I've had it for many years but I'm no expext. I'm just grinding through the menus trying to make sense of all the cryptic parameters.

A couple of things stand out - they lead me to suspect the electronic brake control module (EBCM) at this point. They jury is still out.

1st - the warning lights are gone when you first start the truck. They pop up right away though. Often while the truck is sitting and idling, before it even moves. So that also seems to rule out the wheel speed sensors. This makes me sad because I know how to fix a bad wheel speed sensor.

2nd - I'm not getting an ABS warning light and the Tech2 reports the ABS system status as ok (not failed). If a wheel speed sensor had failed, ABS would also report a problem.

I'll scan again with the Tech2 today. It seems like the next step is to check the EBCM wiring/connector for damage, pull the connector and look at the pins. It's going to rain today and the EBCM is actually under the truck. So I'll probably do that another day.

Keep in mind that the wheel speed sensors are not the only speed sensors on the truck.

 

[Dan_G]

Thanks for all the comments. I'll keep an eye on things. If this was just low brake fluid it's a bit odd they don't have a "low brake fluid" message. That would have been far more helpful than a brake warning lamp and message saying "service brake system" and a TCS off warning lamp. The controller knew the brake fluid was low. I had to dig the code out of the chassis module with a Tech2.

It's all good though. It did get my attention so I'm happy.

 

[Dan_G]

Keep in mind that the wheel speed sensors are not the only speed sensors on the truck.

Yeah, so many sensors, I see there is a speed sensor in the transmission. There are also L+R transfer case output shaft speed sensors. The 07 Denali has so many electronic systems. I have not had to dig into any of that stuff. So far, so good.

 

[Bobio2003]

Change the Brake pedal switch. They are cheap and are a common failure on your model.

 

[Geotrash]

Thanks for all the comments. I'll keep an eye on things. If this was just low brake fluid it's a bit odd they don't have a "low brake fluid" message. That would have been far more helpful than a brake warning lamp and message saying "service brake system" and a TCS off warning lamp. The controller knew the brake fluid was low. I had to dig the code out of the chassis module with a Tech2.

It's all good though. It did get my attention so I'm happy.

As Wes says, it's usually a sign that your brake pads are getting worn. Just to elaborate why: As the pads wear, the caliper pistons are almost fully extended out of their bores, requiring a higher volume of fluid in the system, which the master cylinder supplies until it runs low and triggers the warning. It's probably worth a visual inspection of the pads all around soon.

 

[exxel1954]

I have or had the same issue with my 07 Denali. Had vehicle inspected for registration change yesterday and a bad left front wheel bearing was found. Changed it out and traction control, suspension alert, and service AWD warnings are gone. just a thought

 

[Dan_G]

This was simply low brake fluid. That's all. I checked all the brakes and the were all very worn. So that's where all the fluid went. I wish there was a message that says - low brake fluid - but there isn't. This is the warning you get when the fluid is low.

I just replaced the pads and rotors, front and rear. So it's all good.

 

[Joseph Garcia]

Thank you for posting the solution to your issue. Our collective knowledge base has been increased.