inconvenience or safety feature?

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haviland

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My '22 Stealth engages the brakes at start-up and I have to press the accelerator before taking off. It seems a little crazy to have to disengage the brakes again before starting off. If I'm on a slight downhill it will roll forward in neutral and then I can engage Drive without the brakes being engaged.

Should I be able to take off after starting without feeling the brakes engaged?
 

techdude99

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Brakes at startup? Is this happening on a level surface?

If so, it sounds like your Hill Start Assist is active and the sensor needs to be checked out.

Using Hill Start Assist

1. Press the brake pedal to bring your
vehicle to a complete standstill.Keep
the brake pedal pressed and shift into
first gear when facing uphill or reverse
(R) when facing downhill.

2. If the sensors detect that your vehicle
is on a slope, the system activates
automatically.

3. When you remove your foot from the
brake pedal, your vehicle remains on
the slope without rolling away for
about two to three seconds. This hold
time automatically extends if you are
in the process of driving off.

4. Drive off in the normal manner. The
system releases the brakes
automatically.
 
Last edited:
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haviland

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Sorry for the delay.

Thank you, Loki. I will try waiting several seconds to see if the brakes release. If they don't release, does that mean I've inadvertently activated the Hill start assist feature?
 

HazBeen

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From the 2022 Expedition Workshop Manual...

Hill Start Assist

When the vehicle is stopped on an incline greater than approximately a 6% grade, the Anti-lock Brake System (ABS) module holds the brake pressure for approximately 1.5 seconds while the driver transitions from the brake pedal to the accelerator pedal. This is accomplished by monitoring several Controller Area Network (CAN) messages and several sensors to determine if the vehicle is stopped and not parked, and if the vehicle is on an appropriate incline.
  • The hard-wired brake pedal and wheel speed sensor inputs allow the ABS module to determine the vehicle has come to a complete stop.
  • The transmission selector lever message sent by the Powertrain Control Module (PCM) informs the ABS module the vehicle is not parked.
  • The stability sensor messages sent by the Restraints Control Module (RCM) enable the ABS module to determine if the vehicle is on an appropriate incline.
Once the above conditions have been met, hill start assist automatically engages. Before the driver releases the brake pedal, the ABS module closes the isolation valves which maintains the current brake system pressure, preventing the vehicle from rolling down the incline. Once the driver presses the accelerator pedal and the engine RPM increases, the ABS module gradually releases the brake pressure to make sure the vehicle is neither rolling back nor driving off until there is sufficient driving torque to accelerate the vehicle forward (or backward if reversing up the incline).

Good luck!
 

Attachments

  • Anti-Lock Brake System (ABS) and Stability Control - System Operation and Component Descriptio...pdf
    647.7 KB · Views: 4
  • ABS & Stability Control - Diagnosis and Testing - PINPOINT TEST O - THE HILL START ASSIST FEAT...pdf
    99.7 KB · Views: 4

PhoenixRizez

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I had this happening too. There’s a feature called auto-hold that will do this on level surfaces as well. I don’t remember if it did all the time or only when shifting from Park to Drive, but it was annoying either way. There’s a setting in the menus to turn it off.
 

HazBeen

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From the above-attached System Operation and Component Description document...

Auto Hold

The auto hold feature is activated and deactivated through the APIM (SYNC) message center. For the system to activate, the vehicle must not be moving, the driver safety belt must be buckled and the driver door must be closed.

The Anti-lock Brake System (ABS) module receives the driver safety belt buckle status from the Restraints Control Module (RCM) , driver door status from the Body Control Module (BCM) , while brake system pressure and the wheel speed are received from the ABS sensors. This information allows the ABS module to determine if the vehicle is stopped. Once the previous conditions have been met the auto hold feature can be activated. When the system is activated, the APIM sends an auto hold message to the Gateway Module (GWM) over the High-Speed Controller Area Network 3 (HS-CAN3) and illuminates the auto hold indicator. The GWM relays the message to the ABS module over the Flexible Data Rate Controller Area Network (FD-CAN) .

Once the auto hold feature is activated and the driver presses the brake pedal, the ABS module closes the isolation valves in the Electric Brake Booster (EBB) unit to maintain the current brake system pressure at the wheel ends. The ABS module maintains the pressure until the driver presses the accelerator pedal, shifts the transmission into PARK or after a specific time limit has been reached. The ABS module engages the parking brake after 2-10 minutes, depending on the grade of incline the vehicle is currently stopped on, the steeper the grade, the shorter the time.

Good luck!
 

zak99b5

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This feature seems pretty useless on a vehicle with an auto tranny. Is there something I’m not getting?
 

bocabimmer

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This feature seems pretty useless on a vehicle with an auto tranny. Is there something I’m not getting?
On my driveway with a 7 degree slope, if I just leave the car at idle (without the auto hold) it will roll backwards in D.

If I’m waiting for the garage door to open then continuing forward, it’s really handy.
 

Mr Big

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My 2021 brake engages when I put my vehicle in park. When I shift to D, I either have to step on the gas or push the button to release it.
It was not like this when purchased, but the dealership updated the module for better shifting and it is now a safety feature.
I'm now actually using it on my 2019, because it takes the strain off the drive shaft on my sloped driveway.
 

VBreithaupt

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I have my Expy in the shop for several extended warranty things and the 2024 Explorer I have is doing this? Such a pain to accelerate threw it or push the button to release. Is there a setting to turn off?
 
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