ABS AND Park brake light comes on

[O2 z71]

After running around town a bit, when restarting my 02 suburban 4x4, the cotton-Pickin abs and park brake light come on at start up. They will stay on until I turn off the engine. If restarting overnight, they don't come back on. On e one or two occasions, they've come on after I've started rolling down the road. Is this just my truck that's special? Anyone know the deal with this?

 

[Spriteman]

I guess this could be the ABS/Stop Lamp switch on the brake pedal going bad or not adjusted correctly.

Make sure that the switch is secure in it's bracket and the brake pedal arm is moving the switch plunger just enough to turn it off.

You can push the plunger by hand to see if that turns the light off.

 

[O2 z71]

Look at you, biting off this challenge too.

So that would be the only thing connected to the brake pedal, up at the top under the dash, correct? When I press the pedal, it moves the bar and depresses the plunger.

(btw, with the car off, press the plunger 3-4 times and any backpressure goes away - like all the air is out of it….kind of goes flat almost.)

When I move the brake pedal, there doesn't seem to be any play in either the bar or the plunger (if, of course, i understood what you were pointing me to).

To troubleshoot further, when I am running around town and the lights come on again, you're suggesting I pull in somewhere then get a visual on the plunger and press the brake? The expected result is that the plunger should move as the brake pedal does (if all is working correctly in that combo of goodies, that is).

Do I understand it right?

 

[zora]

personally i think you have an issue with one of the sensors. You need to have a scanner plugged in when the light is on to determine which sensor is causing the issue. The brake pedal getting hard with the engine off is normal for any vehicle with vacuum power brakes.

 

[O2 z71]

Thanks Zora! - I am happy to give that a try also - this scanner thingy you refer to…is it specifically an ABS Scanner or is the usual diagnostic port scanner tool that reads out a code?

 

[Spriteman]

First you might check your brake fluid level - could be as simple as that.

Next - stop lamp switch - see #7 in diagram -

http://parts.nalleygmc.com/showAssembly.aspx?ukey_assembly=372171&ukey_make=1024&ukey_model=14543&modelYear=2002&ukey_category=19539&ukey_trimLevel=14215

Here's the brake switch at Amazon - http://www.amazon.com/ACDelco-D891A-Switch-Assembly/dp/B0013FVXX4/ref=sr_1_1?s=automotive&ie=UTF8&qid=1396468389&sr=1-1&keywords=15128874


Trying to find a good diagram for the wheel speed sensors so you can see those but I'm not finding it.

 

[O2 z71]

Brake fluid is up to max line. Visual inspection of stop lamp switch looks ok - but that don't mean diddly. I guess I can order one, swap that out and hope for the best. Thanks for all the insight! Tony

 

[Spriteman]

We don't like to throw parts at problems - but it is a fairly cheap part - you could remove it and test the continuity.

You might also want to check the wheel bearings and see if you see a loose electrical connection at each of the four wheels.

 

[zora]

the same port is used for scanning but the tool has to be capable of reading ABS

 

[O2 z71]

Zora and Spriteman - thanks - I'll crawl around some more and see if the Autozone reader picks up ABS!
Tony