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Old 08-30-2013, 04:25 PM   #1
Tar Heel
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Default GMC Sierra parking brake light stays on

We have a 2001 GMC Sierra 4.8L 1/2 ton 2WD that we use to tow sometimes. The parking brake light is staying on. I put new shoes on it, they're adjusted correctly and hold tight, and also replaced the electrical switch under the dash that is connected to the actuating foot pedal. Light is still on. Took it to the GM garage (which we never do and goes against everything in me) and after two days they can't figure it out either.

The weird thing to me is that the last time we towed it came on instantly after I disconnected the trailer wire from the plug in the back. ??? I don't know how but I'm thinking it has something to do with the trailering wire and/or brake controller (all of which works fine).

Anyone have any ideas what it could be? Is there a way to disconnect it? We have state inspections in Texas and ours is up next month and I'm not sure if it will pass with the light on even if the parking brake works fine.

Thanks.
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Old 08-30-2013, 07:30 PM   #2
Rob Petrie E395
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Default Re: GMC Sierra parking brake light stays on

Is the pedal coming all the way back up when its released. Try pulling the release handle and pull up on the pedal at the same time. I just had one in my shop where the plastic cover got deformed and got in the way of letting it back up all the way. I clipped a small piece of plastic off of it and it was good to go.
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Old 08-30-2013, 08:46 PM   #3
Tar Heel
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Default Re: GMC Sierra parking brake light stays on

No, that didn't cure it. Thanks for taking the time to respond though. Here's something interesting I just noticed. When you engage the parking brake by pushing the pedal down the parking brake light on the dash blinks. When you release the pedal and the parking brake is off the light stays on solid and doesn't blink. ???
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Old 09-01-2013, 11:27 AM   #4
magnumv8
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Default Re: GMC Sierra parking brake light stays on

If the e- brake switch has 1 wire on it then all the light is looking for is a ground so the light will come on.....so with the wire disconnected from the switch the light will not come on...if removed from the switch and the light stays on, there is a short somewhere between the switch and the light itself....

If there is 2 wires on the switch that usually means the e-brake is being monitored by a BCM (body control module). In which case the BCM is just looking for continuity through the switch to tell it the e-brake is engaged. This makes it a little tougher to diagnose since the BCM controls the light (it can also control and monitor all the systems in the vehicle depending on how new it is). Any spike in the electrical system can cause the BCM,ECU or Dash cluster to fail. Something as simple as plugging in your trailer plug or a problem in the trailer wiring can wreck havoc on the vehicles electrical system.

I don't recommend plugging trailers into a tow vehicle anymore that has the engine running, plus one other thing, manufacturers require us to disconnect every electrical connection to these items plus the batteries and any other monitored piece of equipment on the vehicle before welding on it......

Sorry for the long response (plus a little off track)....

D L Rambo.....Stk1300
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Old 09-01-2013, 07:42 PM   #5
Tar Heel
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Default Re: GMC Sierra parking brake light stays on

Went to pick up the trailer today because we have to dyno tune tomorrow and when we plugged the trailer into the truck (the truck was off) the e-brake light is still on. When we got home I unplugged the ONE wire going to the switch under the dash and the light is still on. Any suggestions what to do? Brakes are working fine on the truck, fluid level is correct, e-brakes on the truck work perfectly, trailer lighting and electric brakes on the trailer are good, ... This is getting a little frustrating.
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Old 09-01-2013, 09:28 PM   #6
magnumv8
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Default Re: GMC Sierra parking brake light stays on

I just finished reading the diagnostic repair procedure for your issue and I am afraid your only choice for repair is to go through a repair facility that has the proper scan tool to diagnose your problem....your truck apparently does have the BCM module and it monitors all of the brake systems, so your issue could be anywhere from a short to a bad switch, sensor or BCM.....the repair sequence has 14 separate steps to diagnose the problem and unfortunately you need the proper scan tool to do it.....

D L Rambo Stk1300
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Old 09-12-2013, 02:17 PM   #7
Tar Heel
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Default Re: GMC Sierra parking brake light stays on

Update:

Took the truck to one of our local GM garages two weeks ago. Long story short the truck sat there for two days without them getting to it so we went and picked it up. Keep in mind we called for an appointment and had to wait a few days and went in when they said to bring it.

It's now at another garage (friend of a friend) so we'll see what they find.

I still have to think it's electrical in nature and not related to the parking brake as it came on when we unplugged the trailer the last time. Tried plugging the trailer back in but that didn't get it to come off.

I'll post when I hear back from the garage.
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Old 09-19-2013, 09:26 PM   #8
Tar Heel
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Default Re: GMC Sierra parking brake light stays on

Low fluid sensor in the brake fluid reservoir was bad. Unplugged the sensor on the side and the light went out. Going to change the reservoir and external sensor. Pretty simple fix for a frustrating problem.
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Old 09-21-2013, 11:03 AM   #9
FrankChastain
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Default Re: GMC Sierra parking brake light stays on

Thanks TH always good to see someone get a real problem fixed and tell others. Like DW says an't nothing like sperence......Frank


Quote:
Originally Posted by Tar Heel View Post
Low fluid sensor in the brake fluid reservoir was bad. Unplugged the sensor on the side and the light went out. Going to change the reservoir and external sensor. Pretty simple fix for a frustrating problem.
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