03 Sierra parking brake

[Local94okc]

So yesterday my “service brake system” light came on all day and didn’t go off 

I got in this morning and the message hasn’t been on all day ...BUT! When I engage my emergency brake the like doesn’t come on showing it’s engaged ....does anyone have an idea of something that could cause this ? Maybe a ground loose ? and if so the locations of the grounds for the brake system

[davester]

Intermittent service brake system warnings (where you get the warning when you run the truck one day, and then it's off for awhile, then happens again), is pretty commonly the ground connection bolted to the wing off the frame under the driver's side door.  Unbolt it, clean the connectors and frame, bolt them back down and smear some dielectric grease over the connectors.

 

As for the parking brake warning light not going on with the parking brake, I would first make sure the bulb works (I think it should come on during the power-on self test when you turn the ignition key on), then check the connector on the parking brake assembly (the pedal mechanism in the cab), maybe the connector has come off, or the switch has failed.

[dtnel78]

Intermittent service brake system warnings (where you get the warning when you run the truck one day, and then it's off for awhile, then happens again), is pretty commonly the ground connection bolted to the wing off the frame under the driver's side door.  Unbolt it, clean the connectors and frame, bolt them back down and smear some dielectric grease over the connectors.
 
As for the parking brake warning light not going on with the parking brake, I would first make sure the bulb works (I think it should come on during the power-on self test when you turn the ignition key on), then check the connector on the parking brake assembly (the pedal mechanism in the cab), maybe the connector has come off, or the switch has failed.

Sounds like he's referencing the same bulb so that would mean the bulb is good. HE describes it as a different light initially but later in his post it seems he's asking why the light isn't coming on then. I could be incorrect. Regardless he needs to check the associated parking brake switch wiring, etc as suggested.

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[davester]

There's two warning lights, an ABS light and the parking brake light,  IIRC, both lights come on, and I get the warning message, when the ABS system reports that service brake system failure, and the parking brake light only comes on by itself when the parking brake is on.  From the original message, it's not clear exactly what lights did come on/stay off when he got the service brake system message.