What Goes On When Releasing Parking Brake

[Wiredawg]

Friends

I realized today while working inside my 2017 Ram 5500 Laramie there's a bunch of stuff going on when you release the parking brake, fob inside truck, not touching anything else. When I released it, doors locked, evic sign said depress brake to start, and possibly other actions. Just found it interesting aside from turning off the brake light, the other stuff going on, likely through the BCM.

I always set the parking brake on all my vehicles, even while parked in the shop on level ground. We were taught that in drivers education in 1973 and the US Air Force reinforced (enforced) it too.

Anyhoo, tired today, but will post more later when I check FSM on this.

Cheers, Ron

 

[HPSimpson]

Some time go outside the truck left side and listen to all the relays and computer's shutting down there is a ton of electronically noise.

 

[TRAMPLINEMAN]

Must just be on automatics. When I release mine, it just releases the brake.

 

[Wiredawg]

Must just be on automatics. When I release mine, it just releases the brake.

What level truck di you have? I'm thinking maybe some packages do different things, maybe programable like auto locking doors.

 

[jhenderson]

On my tradesman, releasing the parking brake does just that, and nothing more.

 

[lpennock]

Could have something to do with being a 5500. PTO and such.

 

[TRAMPLINEMAN]

What level truck di you have? I'm thinking maybe some packages do different things, maybe programable like auto locking doors.

I have a Big Horn with a G56.

 

[Wiredawg]

So,

BTW, I had my driver door open when all this happened... fob was in my pants pocket and was not technically inside the truck. I was checking installation of a gauge and released the parking brake when all I mentioned happened.

Everyone reading this, go out to your truck right NOW with fob, open door, reach in and release parking brake and see what all happens. don't be a woos, a little snow on those bare feet wont hurt.

I have a Big Horn with a G56.

Never been in a G56 4th Gen... Do you have to depress the clutch in neutral or is there any condition where the parking brake has to be engaged to start? Just curious of any safety interlocks on the manual transmission trucks.

Cheers, Ron

 

[TRAMPLINEMAN]

Never been in a G56 4th Gen... Do you have to depress the clutch in neutral or is there any condition where the parking brake has to be engaged to start? Just curious of any safety interlocks on the manual transmission trucks.

Cheers, Ron

Parking brake does not need to be engaged to start. It will start in neutral or in gear with clutch pressed.

 

[gsbrockman]

@Wiredawg
I have a LOWLY Tradesman.....so I do not think I will be able to experience anything like you, since I do not have that Fancy*Schmancy Keyless Enter & Go.

 

[Newsa]

Does the parking brake have to be engaged to initiate high idle? Ir does it just need to be in park?

 

[lpennock]

Does the parking brake have to be engaged to initiate high idle? Ir does it just need to be in park?

On my 18 3500 Aisin you only need to be in park. I think on a Manual the parking brake has to be engaged.

 

[Wayne M.]

ALL current era vehicles have been overrun by tech. For decades DSNY has had, as part of basic vehicle spec, a main circuit (mil style) cutoff in the cab. Since the SCR collection trucks came, that main has been moved out to the frame, and now with the new cab and all its automation, it needed to be eliminated completely to allow the vehicle to power down uninterrupted. The Ford F550’s had to loose the cutoff in 2011. There really is a lot going on even in basic vehicles!

 

[jhenderson]

On my 18 3500 Aisin you only need to be in park. I think on a Manual the parking brake has to be engaged.

Read post 10

 

[lpennock]

Read post 10

Don't understand your point. I was responding to the question about being in park to use PTO mode.

 

[Wiredawg]

Friends,

I checked out my OEM FSM and as you may suspect, there is not a simple switch on the parking brake that illuminates the brake light on the dash. Check this out on a 2017 Ram 5500.

The top blue bar is the Antilock Brakes module which sends and receives signals to the all the brake components.

And here is the whole diagram:

Pretty interesting there is nothing simple on these trucks, even the Tradesman is complex. Later I'll check to see that the fob in my left pants pocket didn't inadvertently hit the first auto start click or remote lock.

Cheers, Ron

 

[jhenderson]

Don't understand your point. I was responding to the question about being in park to use PTO mode.

Excuse me. I mistakenly assumed you were responding to starting the vehicle, as the OP had asked about, not to PTO operation.

 

[Wayne M.]

Ron, not to stray off subject, but since you’re putting up diagrams, do you have one showing the bus network? It’ll illustrate how all the modules are tied together.

 

[BarryG]

I have no idea what all is going on but there have been several times where I shut the truck off and even pulled the key out and still been in it for 10 minutes or so it is amazing how much noise there is over a period of several minutes.

 

[Wiredawg]

Ron, not to stray off subject, but since you’re putting up diagrams, do you have one showing the bus network? It’ll illustrate how all the modules are tied together.

Wayne,

You mean like this?

Also, I analyzed the earlier diagrams I poster and from a simplistic perspective, the BCM is getting inputs to light the brake light, from fluid low, parking brake on, and possibly brake system faults. Also likely error codes/warnings, like I posted on another thread when my antilock brake system pump was malfunctioning, although no brake light, just the warning messages in the EVIC.

Cheers, Ron