If desired you can access the other end of the switch wire here at the BCM...
edit note, in the image I am testing terminal A11.
edit note, in the image I am testing terminal A11.
RED BRAKE LIGHT WARNING CHIMES
- Thread starter Petnatcar
- Start date
I don't think its quite that "easily". Something is strange here. So the poster indicates that the chimes happen even more with the switch unplugged and you are suggesting some sort of issue with the wire along with way..... but if that were true, that "wire situation" would exist whether or not the wire was plugged into the switch. Hence, the switch would have no impact IF the wire is shorted to ground... it will always be shorted to ground.... whether it is plugged into the switch or not.
I am not sure that I "understand" the picture of the switch... is that showing the switch with the hand brake pulled or with it released?
I am thinking that when the brake is pulled, the level contact drops away from the handle and lands on the contact below the contact lever. That contact point may NOT be grounded. Hence, ground is lost if it was from the handle. Hence, it would be loss of ground that indicates brake lever action. Just my guess.... but without some electrical meter testing, I can't see any electric in the picture...
Mooseman
Moderator
If you look at the first pic, it shows the brake lever down, or released, so, as previously thought, when the lever is pulled, the contact goes to ground.
Thanks to @TJBaker57 for the clarification of the switch. It's also a good idea to check what the BCM is seeing at the connector pin (ground or not)
I know what you are saying BUT as I said something doesn't make sense. You indicate that the blue might have an issue (shorted to ground) somewhere along it which is causing a ground signal to "chime". As I was saying whether the wire was connected to the switch or not, there would always be the "fault" in the wire and hence the chime always happen "more" as the poster had stated happened with it disconnected.Anyway, I haven't actually been able to track done a wiring diagram for the switch circuit.... the GM SI isn't very "good" in this area... at least not for me.
Mooseman
Moderator
That could have been subjective since he says it chimes "all the time". I can't see how disconnecting a wire that is connected to an ungrounded switch (as per the pics) would make it chime more. Still, just trying to eliminate that one circuit as the possible culprit. Eliminate the simple first. Then we can look at the more complicated stuff like a fault at the ABS causing it.
It bears a mention that if the wire is tested for resistance to ground while it is connected to the BCM there will likely be about 64k Ohms to ground read through the BCM circuitry. That is what I have on file for the two BCMs I have measured.
Another note: The OP made some comments that most members likely missed as they were inside a quoted block. See post #7.
Another note: The OP made some comments that most members likely missed as they were inside a quoted block. See post #7.
This might be a moot point if unplugging the radio turns off the chimes.
We'll find out later on that count, it's too cold to work in the garage today.
And how do I check continuity?
Continuity is most often tested with an Ohmmeter which is generally included in a "multimeter". These days almost always a Digital MultiMeter (DMM). Most have a continuity test setting and when in that setting the meter will beep when the two test leads are touched together. Just what you need eh? Another thing beeping!
A continuity test is generally done to prove that a wire or circuit is not broken or degraded and that there is little to no measureable resistance to the flow of electricity through the wire.
In the case of your park brake switch what might need to be done is not necessarily just a continuity test but also a test to ensure that the light blue wire hasn't been damaged somewhere along the way and may be now intermittently touching bare metal or another bare wire and getting grounded. If that wire gets grounded AND you are not in PARK the chimes sound. At least that's the way I think it works.
While on that thought..... Does this red brake warning light AND the chimes ever happen in PARK??
More to come.....
Mooseman
Moderator
Yeah, the parking brake chime doesn't happen in PARK.
Makes me think, what else activates the chimes? The seat belt of course, then there's when a gauge is out of spec, like the fake oil pressure or temp (with the check gauges light or DIC message), door open/ajar while in gear, lights on with ignition off.
Makes me think, what else activates the chimes? The seat belt of course, then there's when a gauge is out of spec, like the fake oil pressure or temp (with the check gauges light or DIC message), door open/ajar while in gear, lights on with ignition off.
An alternative to testing for continuity OR testing to see if the blue wire is grounded is to test the DC VOLTAGE at terminal C3, A4 of the BCM with the key in amy position except OFF.
When the key is in any position except OFF then the BCM puts a weak 12 volt signal voltage on that terminal. When the park brake is applied and the switch grounds that wire out the voltage drops to zero, the BCM sees that voltage drop and knows the park brake is on.
If that blue wire is damaged somewhere and grounding out then you should read zero volts at the C3:A4 terminal. If you read 12 volts or close to it then the wire from BCM to park brake switch is not grounding out.
Of course being an intermittent issue means it may test just fine but still have the issue. The only way to be certain is to do the voltage test at a time when the trouble is present and the chimes are on.
When the key is in any position except OFF then the BCM puts a weak 12 volt signal voltage on that terminal. When the park brake is applied and the switch grounds that wire out the voltage drops to zero, the BCM sees that voltage drop and knows the park brake is on.
If that blue wire is damaged somewhere and grounding out then you should read zero volts at the C3:A4 terminal. If you read 12 volts or close to it then the wire from BCM to park brake switch is not grounding out.
Of course being an intermittent issue means it may test just fine but still have the issue. The only way to be certain is to do the voltage test at a time when the trouble is present and the chimes are on.
OP... @TJBaker57 is Right Again...
(1) ALL of your Copper Wire Bonding, Ground Cables & Straps shown in your images are COMPLETELY INFECTED AND CONTAMINATED WITH COPPER OXIDE CORROSION.
(2) Unlike Rust (FE2O3) or "Ferrous Oxide" which WILL mildly conduct Electricity... Galvanic Corrosion that produces Green Copper Oxide (CU2O) WILL NOT and in fact... The Green, Powdery (CU20) Detritus will actually behave like a Dielectric, Non-Conductor instead!
(3) Watch what happens from 2:00 through to 3:40 and later into THIS On Topic Video, because as soon as the Individual Copper Strands Corroded into Green Oxide... the Copper Cable can dissolve, break apart and loses its Bonding and Connection through those Galvanized Steel Eyelet(s). The Flexing Action of Excessive Engine Vibrations is often "The Coup De Gras" that over time, work hardens each individual Copper Strand... until they Fail:
(4) Replacing your Ground Bonding Straps and Cables will STOP the increase amperage draw that happens when your Head Lamps, Left Turn Signal and Fuel Pump Relay fight so much resistance, that the Headlights will Dim when you Turn On the Left Turn Signal ...or the Fuel Pump Relay will Kick Off and cause an Engine Stall:
Here is WHY... A Loose or Bad Ground (SHARED here by ALL THREE SYSTEMS) ) at their common bolt up G107 Ground on the Lower Driver's Side of the 4.2L Engine Block (As explained already by @TJBaker57 ) in Post #8 & Post #20:
(5) Visit @Realism 's Epic "Ground Breaking" Thread HERE to be able to Locate ALL of your Vehicle Grounds AND their Bonding Strap locations and consider replacing the ones involved in the ones with failing circuits and malfunctioning Modules.While there, you'll have a chance to Observe Post#s 4, 5, 7 & 9 and School yourself by watching Paul "Scanner" Danner's Video (Post#9) on the Importance of Knowing HOW to Perform a Voltage Drop Test on the GROUND SIDE of any Circuit:
gmtnation.com
(6) Remember... as Electrical Resistance INCREASES due to Copper Corrosion... Heat INCREASES in the circuit due to Copper Wiring having a "PTC" (Positive Thermal Coefficient)... and thus, ...the Circuit Voltage DECREASES.
(7) Most of your Electrical Gremlins may disappear if you locate and replace the related Bad Ground or Bonding Cables and Straps...and cleaning all of the involved metal surfaces too.
(1) ALL of your Copper Wire Bonding, Ground Cables & Straps shown in your images are COMPLETELY INFECTED AND CONTAMINATED WITH COPPER OXIDE CORROSION.
(2) Unlike Rust (FE2O3) or "Ferrous Oxide" which WILL mildly conduct Electricity... Galvanic Corrosion that produces Green Copper Oxide (CU2O) WILL NOT and in fact... The Green, Powdery (CU20) Detritus will actually behave like a Dielectric, Non-Conductor instead!
(3) Watch what happens from 2:00 through to 3:40 and later into THIS On Topic Video, because as soon as the Individual Copper Strands Corroded into Green Oxide... the Copper Cable can dissolve, break apart and loses its Bonding and Connection through those Galvanized Steel Eyelet(s). The Flexing Action of Excessive Engine Vibrations is often "The Coup De Gras" that over time, work hardens each individual Copper Strand... until they Fail:
(4) Replacing your Ground Bonding Straps and Cables will STOP the increase amperage draw that happens when your Head Lamps, Left Turn Signal and Fuel Pump Relay fight so much resistance, that the Headlights will Dim when you Turn On the Left Turn Signal ...or the Fuel Pump Relay will Kick Off and cause an Engine Stall:
Here is WHY... A Loose or Bad Ground (SHARED here by ALL THREE SYSTEMS) ) at their common bolt up G107 Ground on the Lower Driver's Side of the 4.2L Engine Block (As explained already by @TJBaker57 ) in Post #8 & Post #20:
(5) Visit @Realism 's Epic "Ground Breaking" Thread HERE to be able to Locate ALL of your Vehicle Grounds AND their Bonding Strap locations and consider replacing the ones involved in the ones with failing circuits and malfunctioning Modules.While there, you'll have a chance to Observe Post#s 4, 5, 7 & 9 and School yourself by watching Paul "Scanner" Danner's Video (Post#9) on the Importance of Knowing HOW to Perform a Voltage Drop Test on the GROUND SIDE of any Circuit:
Electrical Ground locations
While troubleshooting a bad ground I came across some scans of the service manual regarding electrical ground locations for our platform posted on another site. This includes both short and long wheel base, as well as both 4.2L and 5.3L. Credit goes to Wex...
gmtnation.com
(6) Remember... as Electrical Resistance INCREASES due to Copper Corrosion... Heat INCREASES in the circuit due to Copper Wiring having a "PTC" (Positive Thermal Coefficient)... and thus, ...the Circuit Voltage DECREASES.
(7) Most of your Electrical Gremlins may disappear if you locate and replace the related Bad Ground or Bonding Cables and Straps...and cleaning all of the involved metal surfaces too.
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Hi Guys,
I stopped the chimes from ever ringing again!
Unplugging the little speakers/tweeters on top of the dash KILLS THE CHIMES as well as the stereo and every other warning sound but the peace and quiet is worth it.
Mooseman
Moderator