The Persistence of Rollaway

In the last three months, two auto manufacturers recalled more than a million vehicles with defects that can cause a failure to lock the vehicle in Park, allowing it to roll away.

Last week, Ford recalled more than 504,000 2013-2014 Escape and 2014-2016 Fusion vehicles over deteriorated bushings that could detach from the transmission shifter cable, allowing the driver to move the shift lever to Park and remove the key, when the transmission is not actually in the Park position. On June 18, Fiat Chrysler recalled 240,242 Chrysler Pacifica minivans because the plastic plug over its Manual Park Release – which allows the driver to override the gear selection – could be pried off without the use of a tool, as required by regulation. A driver could too easily access the release and set the SUV to roll. In April, Ford also issued two safety recalls for nearly 350,000 new F-150 pickup trucks and Expedition SUVs because a roll pin attaching the park pawl rod guide cup to the transmission case was not installed in some of the vehicles, causing the transmission to eventually lose the Park function even when the shifter and instrument panel display indicate that the vehicle was in Park.

Recalls and investigations going back to the 1970s show that rollaway is a persistent and diverse problem. Broken parts, like pawls and rods, still dominate as root causes. But technological changes, such as keyless ignitions and new electronic transmission gear shift designs (e-shifters) have expanded the map. For example, FCA’s notorious Monostable e-shifter, linked to at least 266 crashes, 308 reports of property damage and 68 injuries, was criticized for confusing drivers about the gear state. The design proved so troublesome, FCA abandoned it in the Dodge Charger and Chrysler vehicles after the 2015 model year and in the Jeep Grand Cherokee in the 2016 model year.

In the last decade, NHTSA opened 18 investigations and automakers have launched 93 recalls related to vehicle rollaway. While the causes vary, today’s e-shifters and Electric Parking Brakes (EPBs) give automakers options to prevent it. EPBs have been available for a decade, and can prevent rollaways caused by mechanical failures and driver error. Vehicles with e-shifters can be designed to include automatic Park engagement when the driver doesn’t shift the vehicle into Park. While these features have been available and in use for many years, they still aren’t widespread enough in the U.S. fleet.

New Ways to Rollaway: Novel Shifters

One of the new root causes of rollaway in the modern automobile are new shifter designs that confuse the driver about the state of the transmission. Fiat Chrysler Automotive (FCA) has amply demonstrated the bad consequences of poor transmission shifter design with the introduction of the Monostable and dash-mounted rotary dial shifters.

With the former, the driver changing gears must depress a button on the shift lever and move it to the gear position, then the lever springs back to a centered/neutral position. The gear is displayed on the lever and on the dashboard. In an investigation, NHTSA found that the Monostable shifter was “not intuitive and provides poor tactile and visual feedback to the driver, increasing the potential for unintended gear selection.”

The rotary dial design suffered from poor placement on the dash. Some drivers complained that the interface was “awkward” and it isn’t always clear if the vehicle was actually in Park.  

Chrysler began installing it on the Dodge Ram in 2013, and added it to other models, such as the Chrysler 200 and Chrysler 300. The rotary shifter is located on the instrument panel with the PRNDL displayed both above the shifter control and in the Electronic Vehicle Information Center. Drivers must press the brake pedal to shift out of Park or to shift from Neutral into Drive or Reverse.

The rotary dial shifter’s placement has drivers confusing the knob with another instrument panel control – the radio volume knob. Last month, some sharp-eyed Reddit users and auto website Jalopnik had some fun with a Chrysler Pacifica commercial that showed the driver mistakenly turn the rotary shifter, when she means to turn down the radio volume. (Chrysler Pacifica Commercial Appears to Show Actor Using Transmission Shift Knob to Adjust Volume

Actress Kathryn Hahn plays a mom rocking out to Fergie, as she waits in the school pick-up line for her children. About 25 seconds into the clip, as her children open the car door, Hahn hurriedly reaches to turn down the music – only she turns the rotary shifter – not the radio volume.  

Others complained that the rotary dial itself was confusing, leading them to mistakenly leave the vehicle in reverse, when the transmission was actually in Drive. According to one 2014 Ram 1500 owner in Ivyland, Pennsylvania:

I am sending this complaint regarding the gear selector knob that I believe poses a safety concern due to the 5 or 6 times that I have exited my vehicle while it was running and still in gear. On a few occasions I thought that I turned the gear selector knob to park when I actually turned it to reverse. I opened the door and began to exit my truck when it began to roll backwards. I have a 2010 ram with a normal shift selector lever and never had this issue. I thought that it might take a little time to get used to the knob style, but after 20 months, I am still having issues. I have spoken to others with this style knob and they have experienced the same issue. Each time this occurred was in my driveway either getting the mail or to run into the garage to get something.

Regardless of the way the driver executes a shift, the Monostable and rotary dial don’t physically move the gearshift into a detent.  They send a gear request from the driver via the Controller Area Network (CAN) bus to the Transmission Control Module which then makes the requested shift. In the last three years, these FCA e-shift controlled transmissions have been the subject of recalls, investigations and technical service bulletins. The complaints indicate the possibility of both electronic and mechanical defects.

NHTSA has opened investigations on both of these e-shifters. (See Chrysler’s Shifty Shifter and the Wacky World of Defects and Fiat Chrysler’s Transmission Woes Continue)

New Ways to Roll Away: Keyless Ignitions

Keyless ignition vehicles have also increased the opportunities for rollaway by initiating human errors. In these systems, the “key” is the invisible electronic code which is delivered to the vehicle via the plastic fob. Once the code, via a radio signal, enters the ignition, the fob’s engine activating job is done. You can still use the fob to lock and unlock the doors and trunk, or remotely start the vehicle, but the fob does nothing to turn the car off. The driver must press the Start/Stop button, physically put the transmission in Park and open the driver’s door.

Thus, you can kill the engine, forget to put the transmission in Park, and walk away with fob.

Federal Motor Vehicle Safety Standard 114 Anti-Theft and Rollaway requires a vehicle to be locked in Park or automatically lock into the Park position as a condition of removing the key. But in 2006, as NHTSA amended the standard to address electronic ignition systems, it helped manufacturers avoid actually implementing transmission designs that automatically perform the function by giving them a crib sheet. In the Final Rule, the agency noted:  “Systems using an electronic code instead of conventional key would satisfy the rollaway prevention provisions if the code remained in the vehicle until the transmission gear is locked in the “Park” position.”

And manufacturers did just that – concocting complicated strategies to keep the vehicle in compliance while keeping the driver utterly clueless about the state of the vehicle and ignoring the actual intent of FMVSS 114. Many, many keyless systems address the scenario in which the driver remembers to turn the engine off, but forgets to shift into Park, by reverting the vehicle’s power state to Accessory Mode. That means that some of the vehicle’s electrical functions, such as the radio or headlights still work, and more to the point, the “key” is still in the ignition, while the fob may be tucked into a purse with or a pocket on the driver, miles away.

Most automakers bury this information somewhere in the 500-plus pages of the owner’s manual, so the driver is effectively ignorant of the status of the “key.” Regulations require automaker to warn the driver via an audible or visual warning that the key is still in the vehicle. Most also warn the driver that the transmission is not in Park – because that is a condition of removing the “key” from the vehicle’s ignition module. But many vehicle warnings are poorly executed – visual telltales that will be missed because the driver is not looking at the dash while exiting, or chimes that sound exactly like other vehicle warnings. 

To avoid angering customers who might return to a car with a dead battery, automakers designed systems that automatically turn the power off if the engine is off, but the vehicle ignition is in accessory mode for a pre-set number of minutes. However, in many vehicles this scenario will leave the transmission in whatever gear the driver left it in, free to roll.

In 2011, NHTSA published a Notice of Proposed Rulemaking, in attempt to clean up the mess they made in 2006. The NPRM recognized that the current keyless ignition systems had led to driver confusion, resulting in vehicles left running and/or out of the “Park” position. It also acknowledged that under the current designs, drivers can and do exit the vehicle without the transmission locked in Park, and sometimes without actually turning off the engine. The NPRM noted that the lack of standardization in combination with the lack of visual and tactile cues about the status of the vehicle engine has set the stage for the real world incidents.

The proposal adds a requirement for an internal and external alert that the driver and bystanders can hear when the vehicle is not in “Park”' and the driver exits the vehicle – unless the transmission becomes locked in “Park”' as a direct result of key removal upon door opening, or upon removal of the key code carrying device from the vehicle. (See Keyed Up With Anticipation: Smart Key Hazards Still Unresolved.) 

The NPRM, which was criticized by industry and advocates alike for its non-scientific approach, has not advanced in nearly seven years. But recently, four Democratic U.S. Senators: Bob Casey (D-PA), Dick Durbin (D-IL), Tammy Duckworth (D-IL), and Bill Nelson (D-FL) wrote to NHTSA calling the delay unacceptable and urging the agency to finalize the rulemaking. The senators focused their attention on the CO deaths and injuries associated with keyless vehicles: 

“NHTSA’s lack of action has allowed other automakers to state publicly that their keyless ignition systems meet or exceed all relevant federal safety standards, despite the known and unaddressed dangers. This difference in response across the auto industry highlights the importance and necessity for a federal standard to be established and enforced without further delay,” they wrote.

Broken Parts

The majority of vehicle rollaways are caused by a wide range of mechanical, software and electronic failures. Out of a total of about 160 rollaway recalls since the 1970s, the vast majority are related to material or manufacturing deficiencies. Numerous vehicle components, such as the brake-to-shift-interlock failures, and drive shaft and axle can breakages, have led to a rollaway. In addition, vehicle software and electrical circuits can introduce problems that lead to the same condition. Consider these four recalls from the past few years:

  • In December 2015 Ford recalled 1,170 Transit vehicles from the 2015 model year equipped with dual rear wheels were mis-manufactured. An analysis of fractured drive shafts obtained from some of these vehicles found indication of unacceptable material grain flow during the forging process that could lead to axle fracture. A fractured axle could result in a loss of motive power or unintended vehicle movement when the transmission shift lever is placed in the Park position without the parking brake applied.
  • In May 2017, Volkswagen recalled five Audi Q5 vehicles with a gearbox manufacturing defect. Volkswagen stated that when the shift selector is moved to the Park position the gearbox may not engage the parking pawl, leading to a false park and potential for a rollaway.
  • In July 2017 FCA recalled 7,802 2017 Dodge Challengers for a software flaw that could inhibit the transmission from maintaining mechanical Park when the shift lever is moved to the Park position. FCA described the problem as Transmission Control Module software that “introduced longer clutch pressure vent gradients to improve shift quality. A longer clutch pressure vent rate increases the rate at which these vehicles may set a P1DDD fault. Setting a P1DDD fault will result in the vehicle automatically shifting into a 6th-gear limp mode instead of PARK.Vehicles experience P1DDD when venting the clutch pressure takes longer than 1.25 sec and too many clutches are still engaged.”“When a P1DDD fault is set the shifter will show “D”, the instrument cluster will show “D”, the instrument cluster will show a warning message “Service TransPress Brake When Stopped Key Off Engine to Engage Park”, and a repeating audible chime will sound. If the door is opened a “Vehicle Not In Park” message will also be displayed, the EVIC will alternate between the two messages and continue to chime.”
  • In November 2017 Toyota recalled 2018 model year C-HR vehicles because an oxide film could form on the electric parking brake (EPB) motor, as an open circuit, when the EPB has not been operated for a while. ECU identification of the open circuit would result in illumination of warning lights and a message displayed which states: “EPB Malfunction. Visit Your Dealer.” The condition could cause the parking brake to fail to release and in some cases, it can prevent the parking brake from being applied.

Rollaway Countermeasures for the Modern Age

Keyless ignition vehicles will only become more ubiquitous. Who knows what thrilling new transmission shifter will start a whole new round of automotive mayhem?

In the meantime, the industry has had two countermeasures at its disposal to keep a vehicle in place: the electric parking brake in tandem with auto-hold features. The electric parking brake has been around since at least 2001. According to a 2015 press release from supplier TRW, FCA was among the automakers who have implemented this feature: “ZF TRW was first-to-market with its EPB system in 2001, which pioneered with Lancia, Audi and VW and has since launched on Renault, Nissan and Daimler platforms, and more recently on the BMW X4 and BMW i8, Jeep Renegade, Fiat 500X, Ford F150, Honda Accord, Nissan Qashqai, Range Rover Evoque and more.”

EPBs replace manual parking brakes to hold the vehicle stationary on hills and flat roads.

They have been touted as the more economical choice, both in terms of interior space and per-unit cost. The manual parking brake lever or foot pedal was replaced by a small switch, and there were fewer mechanical parts to wear out:

“With EPB, the driver activates the holding mechanism with a button and the brake pads are then electrically applied onto the rear brakes. This is accomplished by an Electronic Control Unit (ECU) and an actuator mechanism. There are two mechanisms currently used in vehicle production, cable puller systems and caliper integrated systems, such ZF TRW’s EPB. In caliper integrated systems, the brake caliper provides a connection between hydraulic actuation of the foot brake and electrically actuated parking brake. The motor or transmission unit (actuator), which operates the parking brake, is screw-fixed directly to the brake caliper housing. The parking brake is actuated via a switch in the vehicle interior. The absence of a hand brake lever frees up space inside the vehicle. With no hand brake cables, there are no temperature problems (such as freezing) or mechanical wear, offering optimum brake power in all conditions."

 

The improved passive safety features included various versions to keep vehicles from rolling. For example, one article notes: “On the other hand if the driver forgets to apply the park brake it may be programmed to operate automatically, if the gear select lever is in Park or Neutral and the seat belt is released as the door is opened. Not all manufacturers offer this sort of facility.”

TRW’s auto-park feature specifically applies the parking brake in scenarios in which the vehicle transmission is in a gear other than Park and the driver opens the door to exit. According to a 2002 technical paper by a TRW engineer: “Another conceivable function is an automatic application command if the driver leaves the driving seat when the vehicle is at a standstill (e.g. detected by seat-occupant detection or the door switch).”

Some manufacturers use this type of technology. For example, the Hyundai Genesis, as far back as 2010, has a feature called Auto Hold in models with the Electric Parking Brake (EPB): “The AUTO HOLD keeps the vehicle stopped after the driver brings the vehicle to a complete stop with the foot brake and releases the brake pedal.”  The AUTO HOLD doesn’t operate when the driver’s door is open and/or the Shift lever is in Park. However, it automatically switches to the EPB in a variety of scenarios, including: “the driver's seat belt is unbuckled and the driver's door is open.”

In the 2014 model year, FCA added a similar feature to the Jeep Cherokee: “Safehold is a safety feature of the Electric Park Brake System that will engage the park brake automatically if the vehicle is left unsecured while the ignition switch is in RUN.” For automatic transmissions, the park brake will automatically engage if the vehicle is at a standstill, there is no attempt to depress the brake pedal or accelerator pedal, the seat belt is unbuckled and the driver door is open.

In the 2016 Monostable shifter recall campaign, Fiat Chrysler fixed the rollaway problem in some of its vehicles by installing a different strategy – also called AutoPark. FCA describes it “is an enhanced securement strategy which places the vehicle in “PARK” if the driver attempts to exit the vehicle before placing the rotary gear shift selector in the "PARK" position.” Rather than apply a parking brake, this feature – which can be included in any vehicle with an E-shift control and minimal software, is used by other manufacturers, actually moves the transmission into the Park position. FCA also added this feature to the 2017 Dodge Ram.

As more vehicle makes and models employ electronic shifters or add electric parking brakes, it may be possible to reduce the number of rollaway incidents. In the meantime, rollaway caused by design errors (including those that increase the likelihood of operator error), manufacturing defects and mechanical failures will continue to wreak its unique form of property and human damage.

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