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magnumv8 · 09-01-2013, 11:27 AM

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

09-01-2013, 11:27 AM	#4
magnumv8 Member Join Date: Feb 2009 Location: Coraopolis, Pa. Posts: 172 Likes: 0 Liked 0 Times in 0 Posts	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