Zero has issued a new recall for 2012 and 2013 bikes to properly handle Sevcon controller faults.
On Sep 17 2012 Zero first notified the NHTSA of a
controller glitch caused by motor encoder drift. This is the original glitch.
For better readability, everything between '****' is a quote from Zero's defect report.
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DESCRIPTION OF DEFECT:The subject motorcycles have a motor encoder position signal that may drift over the extended use of the motorcycle. Should the encoder signal drift too far, it could fall beyond the signal limits expected by the motor controller. This condition could cause the motor controller to shut off, resulting in the inadvertent loss of power of the motorcycle, which could lead to a possible crash and potential injury or death of the rider.
CHRONOLOGY OF EVENTS:On 02/10/2012, Zero Motorcycles received a report of a 2012 Model Year (12MY) OS model motorcycle (538SD3M3XCC  ) that stopped running inadvertently. Zero Motorcycles Engineering was made aware of this issue and began an investigation in collaboration with Zero Motorcycles Customer Service department. At the time, the incident was attributed to a defective motor.
On 05/04/12, Zero Motorcycles received a report of a 12MY S model motorcycle (538SM3M34CC  ) that stopped running inadvertently. At the time, this incident was attributed to the condition that led to Zero Motorcycles' BMS weatherproofing recall (12V-310).
On 06/12/12, Zero Motorcycles received a report of a 12MY S model motorcycle (538SM3M32CC  ) that stopped running inadvertently. With this incident, the investigation team became suspicious of properly understanding root cause. This specific case was investigated further and eventually traced to poor motor / controller timing. A re-timing procedure was put in place that appeared to resolve this occurrence.
On 07/06/12, Zero Motorcycles received a report of a 12MY S model motorcycle (538SM3M36CC  ) that stopped running inadvertently. This incident was also traced to poor motor / controller timing, and the re-timing procedure was applied to this bike.
On 07/18/12, Zero Motorcycles received a report of a 12MY DS model motorcycle (538SD3M31CC  ) that stopped running inadvertently. This incident was also traced to poor motor / controller timing, and the re-timing procedure was applied to this bike. However, although this repair appeared effective, Zero Motorcycles was later advised that the condition had recurred.
On 08/09/12, Zero Motorcycles received a report of a 12MY S model motorcycle (538SM3M30CC  ) that stopped running inadvertently. This incident was also traced to poor motor / controller timing, and the re-timing procedure was applied to this bike. However, although this repair appeared effective, Zero Motorcycles was later advised that the condition had recurred.
On 08/13/12, Zero Motorcycles received a report of a 12MY S model motorcycle (538SM3M32CC  ) that stopped running inadvertently. This incident was also traced to poor motor / controller timing, and the re-timing procedure was applied to this bike.
On 09/04/12, Zero Motorcycles received reports of a 12MY S and DS model motorcycles (538SM3M35CC  and 538SD3M3XCC  ) that stopped running inadvertently. Zero Motorcycles Customer Service advised both dealers of the ongoing investigation regarding the motor / controller timing condition and that a more definitive solution was being explored.
On 09/05/12, this concern was brought to the attention of Zero Motorcycles' Product Integrity Team. This group spent the next week analyzing all of the data and ensuring a good understanding of the concern and its possible effects.
On 09/05/12, Zero Motorcycles received a report of a 12MY DS model motorcycle (538SD3M36CC  ) that stopped running inadvertently. Zero Motorcycles Customer Service advised the dealer of the ongoing investigation regarding the motor / controller timing condition and that a more definitive solution was being explored.
On 09/06/12, Zero Motorcycles received reports of a 12MY S and DS model motorcycles (538SM3M31CC  and 538SD3M33CC  ) that stopped running inadvertently. Zero Motorcycles Customer Service advised both dealers of the ongoing investigation regarding the motor / controller timing condition and that a more definitive solution was being explored.
On 09/12/12, Zero Motorcycles received a report of a 12MY S model motorcycle (538SM3M34CC  ) that stopped running inadvertently. Zero Motorcycles Customer Service advised the dealer of the ongoing investigation regarding the motor / controller timing condition and that a more definitive solution was being explored.
On 09/12/2012, Zero Motorcycles completed its internal investigation of this issue and concluded that the encoder signal used on 12MY S and DS motorcycles built on or prior to July 23, 2012 could drift beyond the signal limits expected by the motor controller, which could lead to a quits-while-running situation. Zero Motorcycles executive management considered this information and determined that a defect related to motor vehicle safety existed.
Zero Motorcycles is not aware of any accidents or injuries caused by this condition.
DESCRIPTION OF THE PROGRAM TO REMEDY THE DEFECT:The remedy of this defect is for authorized Zero Motorcycles dealers to reprogram the motorcycle's motor controller with a new firmware and configuration, which compensate for the possible drift of the motor encoder position signal to ensure it remains within the limits expected by the controller.
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On Dec 18 2013 Zero notified the NHTSA of another recall to
properly handle continuing glitches.
Again, for better readability, everything between '****' is a quote from Zero's defect report.
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DESCRIPTION OF DEFECT:The subject motorcycles have a controller firmware that may react to infrequently encountered signal faults by discontinuing controller power to the motor. Should one of these faults occur while the motorcycle is being ridden, the controller's response may result in an inadvertent quits-while-running condition, which could lead to a crash.
CHRONOLOGY OF EVENTS:On 09/12/2012, Zero Motorcycles concluded that certain 2012 model year motorcycles had a motor encoder position signal that could drift over the extended use of the motorcycle. Should the encoder signal drift too far, it could fall beyond the signal limits expected by the motor controller. This condition could cause the motor controller firmware to respond to such a signal fault by discontinuing power to the motor, resulting in the inadvertent loss of power of the motorcycle, which could lead to a possible crash. In response to the conclusion of its investigation, Zero Motorcycles determined that a defect related to motor vehicle safety existed and declared a voluntary recall program (12V-455). The remedy in this program involved a new controller firmware and configuration, which compensates for the possible drift of the motor encoder position signal to ensure it remains within the limits expected by the controller.
Over the next several months, Zero Motorcycles received reports of 2012 and 2013 model year motorcycles that exhibited similar quits-while-running behavior. Since the analysis of each of these reports revealed a variety of unrelated faults as the root cause of the inadvertent power interruption, on 09/20/2013 Zero Motorcycles personnel traveled to Sevcon's headquarters in the United Kingdom to better understand the reason behind such behavior (Sevcon Limited is the manufacturer of the subject controller and developer of its firmware). During the ensuing investigation after this meeting, it became clear to Zero Motorcycles and Sevcon that these random, infrequent and unrelated signal faults could not be avoided in the lifetime of the motorcycle, and that the controller firmware needed to deal with these faults in a different, more reasonable manner.
On 12/05/2013, Zero Motorcycles completed its internal investigation of this concern and concluded that 2012 and 2013 model motorcycles built with a Sevcon controller prior to 11/08/2013 have firmware that could respond to infrequent signal faults by discontinuing controller power to the motor, which could lead to a quits-while-running situation. Zero Motorcycles executive management considered this information and determined that a defect related to motor vehicle safety existed.
Zero Motorcycles is not aware of any accidents or injuries caused by this condition.
DESCRIPTION OF THE PROGRAM TO REMEDY THE DEFECT:The remedy of this defect is for Zero Motorcycles dealers to update the suspect vehicles with revised controller firmware that deals with these infrequent faults in a way that does not result in an inadvertent quits-while-running condition.
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