M923 Parking Brake Alarm/Buzzer Delete

[rivercreek]

I'm puzzled.. Perhaps someone has some input on this subject. Short history: We spend long hours on standby for snow removal while parked (brake set). I've found that some of my drivers are not applying the parking brake simply because they are tired of the racket. I'd prefer to eliminate the buzzer and thus eliminate their excuse for not applying the parking brake for obvious reasons. My research of the wiring schematic seems to show the switch in the parking brake lever simply completing (on) or interrupting a ground (off) as the signal to the buzzer. Proceeding on that understanding, I snipped the wire on the chassis ground side of the switch. To my surprise, the buzzer stayed on the entire time, regardless of lever (switch) position. It seemed to me as I understand this circuit that this should not happen. Any input/advice would be much appreciated.

Closing Statement: I am very aware that there are many who would say that the parking brake buzzer is there for a reason, and therefore one should not attempt to disable it. Before you respond as such, please consider my situation. I have 5 of these trucks on the road (not all driven by me, obviously) that often sit parked for 12 + hours at a time, and frankly, I believe that I will sleep much better at night knowing that there is no reason for them to NOT set the brakes on my trucks while parked. I've spent many days in these trucks myself, and 12 hours of that buzzer would drive the Pope crazy, I am reasonably certain. To me, this becomes a decision of the lesser of two evils. I'd prefer to not have a deterrent to drivers setting parking brakes while parked. That to me is a much better scenario than to make it intolerable for someone to sit behind the wheel of a parked M923 for 12 hours straight.

 

[The HUlk]

Applying the brake opens the switch. Releasing the brake closes the switch. This is known as a normally closed circuit whch is common in safety circuits. When a wire breaks or contact fails the alarm sounds until it is solved is the reason for the seemingly backwards design. Connect wire 584 from PIN I on the buzzer module to ground.

 

[rivercreek]

Thank you very much Hulk. After reading your explanation and solution, I'd be lying if I didn't admit to feeling a little dumb... Thanks again.

 

[The HUlk]

We all get lost in the trees while looking for the forest sometimes.

 

[The HUlk]

I was thinking, you could have the best of both worlds by splicing a grounded switch to wire 584 for an added "Parking Brake Buzzer Overide" function. Switch it on when parked for long periods and off during normal operation. Splicing into the wire in the dash would make a great place for the switch.

 

[VPed]

Good suggestion by the Hulk. You could also consider using a relay and momentary push button. It could be set up so that the relay drops out when the main power or ignition switch is turned off, making the "buzzer on" the default. Pushing the button would latch the relay, disabling the buzzer for as long as the truck remains on.

 

[The HUlk]

Good suggestion by the Hulk. You could also consider using a relay and momentary push button. It could be set up so that the relay drops out when the main power or ignition switch is turned off, making the "buzzer on" the default. Pushing the button would latch the relay, disabling the buzzer for as long as the truck remains on.

Adding a second normally closed momentary push button switch in the latching circuit would deactivate the overide relay without the need to cycle power.

 

[steelandcanvas]

Applying the brake opens the switch. Releasing the brake closes the switch. This is known as a normally closed circuit whch is common in safety circuits. When a wire breaks or contact fails the alarm sounds until it is solved is the reason for the seemingly backwards design. Connect wire 584 from PIN I on the buzzer module to ground.

Great explanation. Also known as a "supervised" circuit.

 

[74M35A2]

I had the same concern, but I simply placed tape over the alarm to reduce it's noise level, but I don't sit in the truck as long as your situation with the park brake on at idle.

 

[rivercreek]

I was thinking, you could have the best of both worlds by splicing a grounded switch to wire 584 for an added "Parking Brake Buzzer Overide" function. Switch it on when parked for long periods and off during normal operation. Splicing into the wire in the dash would make a great place for the switch.

A big thanks to everyone for the great ideas and input. Hulk, I believe the override switch that you suggested will be the simplest effective means to achieve my goal without permanently disabling the parking brake alarm. I believe I will install said switch in an "undisclosed location".

 

[GasTurbineTech]

I am resurrecting this thread to show my buzzer override.

I moved the low air light over 1 spot and put the override push button in its spot (I wanted stock parking brake light & override next to each other)

Many have questioned safety, but the buzzer on when the PB is engaged with in neutral is not needed. This override button gives me a visual indicator but no buzzer. As shown in the video, you can hear the low air buzzer still works, this button doesn't interfere with it at all. The video shows the air pressure rising enough to cut out the low air switches.

I spliced in to wire #584. This button grounds this wire when pushed in, shutting off the buzzer (while turning button halo blue). I used a relay because a dpst illuminated button was not easily found.

PB light on, override button off, Low air light on

PB light off, override button on, low air light on

Sorry, wouldn't take my edits to shorten video...
https://vimeo.com/167451763




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[Landbarger]

Thanks for this thread GasTurbine. I'd like to read back through it a couple of times. Maybe I can figure out how to wire a buzzer to my PTO so that I don't try to take off with it engaged...again.

 

[TEAMJENSEN]

I'm new to the forum as I just purchased my first m923a2. Upon starting the truck with park brake on, the buzzing I hear in the videos is not sounded nor is the red light on the dash visible. I fo idle before I release the park brake upon desired 120 lbs in both tanks. I know the buzzer and light are for safety so I want to find the problem. Any suggestions? Thank you in advance.

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[simp5782]

check to the bulb to ensure it is not blown. Buzzer could be just bad. They do go out. Or smack it with a hammer. You need to pull the bulb and see if you have power at the light with the parking brake on and the truck running. That is how you will know where to start.

Could be a bad parking brake switch. Could be a broken wire somewhere. So check to see if you have power to the bulb and that the bulb is good. Then chase the buzzer.

 

[TEAMJENSEN]

Thanks! So bulb is good. No power at bulb. Tring to trace wires not sure where buzzer is located. Any thoughts?

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[TEAMJENSEN]

So I found the large wire harness that the park brake on light plugs into module for buzzer. It was unplugged. Now once I plugged it in the buzzer and park brake works. Thank you!

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[TEAMJENSEN]

Took a ride. The red light went out and the buzzer stopped when the air reached 120 and I took park brake off. Went only a little ways and the stinking buzzer sounded and the low air light blinked constantly. The primary and secondary gauges are at 120 and still a buzzer and low air light blinked whole trip. Any idea where to go from here?

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[simp5782]

Took a ride. The red light went out and the buzzer stopped when the air reached 120 and I took park brake off. Went only a little ways and the stinking buzzer sounded and the low air light blinked constantly. The primary and secondary gauges are at 120 and still a buzzer and low air light blinked whole trip. Any idea where to go from here?

Sent from my SM-G950U using Tapatalk

There is a switch on the parking brake. You need to take it and complete the circuit and see if it continues

 

[simp5782]

Took a ride. The red light went out and the buzzer stopped when the air reached 120 and I took park brake off. Went only a little ways and the stinking buzzer sounded and the low air light blinked constantly. The primary and secondary gauges are at 120 and still a buzzer and low air light blinked whole trip. Any idea where to go from here?

Sent from my SM-G950U using Tapatalk

I missread. So the low air light blinked while you were driving? Then you need to check the continuity on the sensors on the tanks to ensure which one is causing an issue. Not the parking brake. My bad.

 

[99nouns]

I just unscrewed the buzzer plug and left it hanging there, nothing fancy but got rid of the noise and the light, but again I am the only one driving it. Maybe I need to stop hanging out with the swamp culture.