'Brake Light' and 'Service Brake System' illuminated o

[cashflow50]

2003 GMC Yukon 4.8L 2wd SLE

 

Just replaced my Brake Pads and Rotors on all 4 wheels yesterday. Bled the system with the vac connected to compressor and took the truck for a spin. Brake pedal too low and spongy, so there were still bubbles in the system. Instead of connecting the vac, I bled the system the 2 man old fashion way (pump pump pump and hold on the brake pedal). Started the bad boy up and the 'brake light' and 'service brake system' is illuminated on the DIC. Took it for a spin and had full stopping power. Brake engaged at minimal pedal press and wasnt spongy. The thing is what could have tripped the brake light and service brake system on the dic? My partner and I was baffled and tried googling if anyone knew how to reset or fix this. We spent about 2 hours trying to recreate the steps that we could've gone wrong, but everything looked good. Does anyone have a clue. Need help cause this is my wife's ride and wont use it unless I clear the codes.

 

-prior fixes but might be unrelated-

replaced ECBM in 2013 (ECBM repaired by Module Master)

 

 

please help. Thanks.

 

 

[Jsdirt]

You'll probably have to clear the code or codes with a scan tool before it will go away. It probably set the warning off when it detected the long pedal travel with little line pressure, due to air. Also may have been a little air in the ABS unit.

 

Could try a few hard ABS stops in gravel or sand, and see if that turns the light off. If not, you'll have to go in and clear it.

[cashflow50]

Does autozone or other shop have these scan tools to clear or only dealership has the tool? If you don't mind me asking how does hard stopping on gravel or sand do the trick?

[Jsdirt]

If the code is in the ABS module and not in the PCM, you'll need a bi-directional scan tool. Any garage will have one.

 

Stay away from any dealer!!

[BiggG74]

Don't they reset when you go through a few drive cycles? Mine is a 2000 and it did just curious. My issue was the abs sensor had been loosened on front rotors with brake change. Probably got bumped.

 

 

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[Jsdirt]

It might, but if you want it off for sure, and NOW, a bi-directional scan tool is the only way.

 

Like I said - any garage will have one. It's a necessity in this day and age.

[cashflow50]

Spoke to a tech yesterday about my issue and through his experience with working around the mechanics..he said that when we test drove after the first bleed along with the low spongy pedal, he thinks there is a good amount of air pockets in system. That triggered the code and only be rest by a scan tool used in big shops. Not the regular autozone stuff. Thanks Jsdirt for the help.

 

By the way I've noticed that my brake fluid res doesn't have a sensor anywhere on it. No wires or connectors. Is this odd? All the people i know that has the same engine type as mine has one connected to the res. Does anyone know where my is or I'm just smoking crack?

[Duelin]

I would take a look at the Proportioning Valve. Could be off center and causing the brake light to come on. This can happen when there is more pressure on one side of the system compared to the other side (like when bleeding brakes). It thinks there is a leak and tries to shut off that side of the system and turns the light on.

[cashflow50]

I would take a look at the Proportioning Valve. Could be off center and causing the brake light to come on. This can happen when there is more pressure on one side of the system compared to the other side (like when bleeding brakes). It thinks there is a leak and tries to shut off that side of the system and turns the light on.

Where does this Proportioning valve located? How do I get it to center?

[Jsdirt]

It's either below the master cylinder along the fire wall, or under the vehicle around the driver's seat. Just looks like a block of metal with 3 or more lines going in, not to be confused with the ABS unit. The proportioning valve is small by comparison.

 

You could try giving it a few light taps with a hammer while someone pumps the brakes - might free it up. Could try disassembling it and spraying it out with brake clean and compressed air if that doesn't work. There used to be an adjustment screw if I remember right - doubt anything this new would have that though.

[cashflow50]

JS how does the hard braking on gravel fix or help diagnose the 'brake light' and 'Service Brake System' on the DIC? Sorry noob question. thank you.

[Jsdirt]

If there's air trapped in the ABS unit, activating the ABS will sometimes purge the air out of the unit and into the lines where it's much easier to be bled out.

 

Without a bi-directional scan tool, the only way you're going to get the ABS motor to run, is by locking up a wheel or 2.

[cashflow50]

Thanks guys for the help. All along it was a stuck valve. I'll will try jarring it loose as how Jsdirt stated. If that doesn't work i'll just get a new one on amazon or ebay.

[Duelin]

The piston in those valves will slide to one side or the other due to higher pressure on one side (usually happens when there is a leak in the system). You will have to figure out which which side you need to create the high pressure on in order to get the piston to slide back towards the center.

[cashflow50]

The piston in those valves will slide to one side or the other due to higher pressure on one side (usually happens when there is a leak in the system). You will have to figure out which which side you need to create the high pressure on in order to get the piston to slide back towards the center.

Yah I read somewhere where you open up one front bleeder and push the pedal until the light goes out then hold ....tighten the bleeder up. This should center the valve. If that doesn't work then just replace the bad boy.