2007 Yukon Denali - Brake - Traction Control warning lamps

[Dan_G]

Hi, I have a 2007 Yukon Denali. I have the dreaded Traction Control Off warning lamp and the brake warning lamp. For some reason, no ABS warning lamp. Just Traction Control and Brake. These lamps come on right away after starting the truck. Sometimes before the truck even moves. Any help would be appreciated.

Here is what I know so far. I have a Tech2 scan tool. There were no DTCs in the PCM or the other modules. The scan tool data shows these things:

All 4 wheel sensors show the wheel speed in mph, and these speeds match for all 4 wheels and the readings go up and down as the vehicle speed changes. Wheel speed sensors seem ok.

ABS Active – No

ABS Failed - No

VSES Active – No

VSES Failed – Yes

TCS Active – No

TCS Failed – Yes

I also checked all the fuses in the under hood fuse box. No blown fuses. I know there is an electronic brake control module (EBCM). I see it there under the car. The wires look ok. This could be a possible cause. I have an AlldataDIY account so I have access to some schematics and pin-outs. What else should I check to narrow this down. If all else fails, I can engage the parts cannon and buy an EBCM.

 

[Foggy]

Many times a CEL Check Engine Light will trigger the traction control system.
You'll need to scan your codes and fix problem and clear out codes.
Its a safety thing to let you know that with certain codes the other systems will not
function correctly.. (many times totally unrelated)

 

[Dan_G]

Thanks, I did a scan using the GM Tech2 scan tool. Sadly no check engine lamp, no diagnostic trouble codes. No blown fuses. No ABS lamp. No symptoms when driving. Brakes feel fine.

Just the Traction Control Off warning lamp and the brake warning lamp and it chimes likes 20 times and that repeats from time to time.

 

[Fless]

Check the Chassis codes with your Tech 2. The list you posted shows that the VSES failed, and that should show a C0xxx code. That's what's probably triggering the warning lamp. If the code doesn't show, check it when the light is on.

 

[Dan_G]

Ok will do. I did scan the chassis module - no codes with the truck not running as you probably suspected. I'll try again tomorrow and make sure the warning lamps are on this time.

 

[swathdiver]

You can also view the failure records.

VSES failure usually refers to one of the rear ABS wheel speed sensors. I just had a dealer stretch one out when they pulled the bed off my pickup and it set off the code. But don't take my diagnosis as gospel, the Tech-2 will tell you.

 

[Dan_G]

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.

 

[Doubeleive]

sounds like a faulty brake fluid level sensor, unplug the sensor and see if the problem goes away.
did you do any brake work recently? if so it could also be the proportioning valve is stuck
brake and abs are separate, brake light with no abs light would point to my top line.

 

[Dan_G]

Well this is embarrassing. I checked the codes today. There was a code for low brake fluid level. I checked the level again and sure enough it was a tiny bit low. Not sure what I was looking at last time. I added some brake fluid and checked the wiring and connector for that sensor. Sure enough, the brake warning lamp went out. The TCS stayed lit for a while but it’s out now. So we will see if it comes back. So that looks like the culprit (user error).

 

[Doubeleive]

Well this is embarrassing. I checked the codes today. There was a code for low brake fluid level. I checked the level again and sure enough it was a tiny bit low. Not sure what I was looking at last time. I added some brake fluid and checked the wiring and connector for that sensor. Sure enough, the brake warning lamp went out. The TCS stayed lit for a while but it’s out now. So we will see if it comes back. So that looks like the culprit (user error).

the traction control could be a separate issue, I would keep the tech2 handy and if it lights up scan it while the error is active. those types of codes can clear themselves if it passes on a key cycle but "might" remain in a historical list.