Corolla Electric Power Steering PE10-008

16 June, 2010

Outline• Steering Development• Steering Testing and Standards• Field Information• Clarifying Customer Feedback• Explanation of “Wander” or “Drift”• Simulation & Comparative Testing• Toyota Assessment

’09-10 Corolla Steering Development• Based on market research and competitor vehicle

benchmarking, Toyota aimed to improve:– Steering feel– Vehicle agility– Ride comfort

• In dynamic testing, development vehicles compared favorably to other models

Developmental Dynamic Safety Testing

Confidential Information Redacted

Developmental Dynamic Safety Testing

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Description of the EPS system　 System Outline

• New for the 2009MY Corolla and Matrix as standard equipment

• Utilizes an electric motor and reduction mechanism to provide assist torque to the steering shaft

• ECU calculates the appropriate amount of assist to provide to the steering shaft

• The benefits include improved overall fuel economy

Description of the EPS systemDesign Concept

Confidential Information Redacted

Steering Testing & Standards• Toyota has 3 standards:

Steering effort when slowly operating steering wheel at standstill

Steering effort when quickly operating steering wheel at standstill

Vehicle behavior and steering characteristics before and after EPS fail-safe mode activation

• Vehicles surpass all standards above

• Also complies with ECE 79 (Europe) and GB 171675 (China) which specify steering effort for normal driving and when steering assist fails.

Steering Effort Criteria• Corolla EPS surpasses regulatory requirements for steering effort

under power assist failure

Criteria & Recommended Values of Steering Effort

Field Information• VOQ’s - Over 80% of VOQ’s had descriptions of steering “wander” or “drift”

• Consumer Complaints - A majority of complaints received by Toyota

also appear to generally describe a steering “wander” or “drift”

• Warranty - A high percentage of claims involve adjustment (such as wheel alignment) rather than parts replacement

• Field Reports - Majority of reports are not related to “wander” or “drift”

• Crash Cases - Insufficient information is available on crashes to assess cause, but no defective parts found in those vehicles which were inspected

Clarifying Customer Feedback• Toyota interviewed 107 customers (all submitted VOQ’s) to understand their complaint of steering “wander” or “drift”

• 90% described what can be characterized as a vehicle “wander” or “sensitive” steering

• Toyota engineers inspected and drove 87 of those vehicles

• In all vehicles, no defect was found in the steering system

• Steering feel of all vehicles was found to be consistent with design intent and within acceptable production variation with no significant deviation

Explanation of “Wander” or “Drift”• Based on the design concept, the neutral area steering effort is slightly stiff

• Vehicle reacts when steering input exceeds the self centering force of the vehicle

• When self centering force is exceeded, the vehicle moves according to the steering angle

• Some customers may complain of a delay at this transition point and perceive slightly “stiff” steering

Explanation of “Wander” or “Drift”

Undulation

Slant

Cross Wind

“Drift”

“Wander”

Disturbance

• Based on road conditions and external inputs, some customers may perceive a “wander” or “drift” due to the slightly stiff on-center feel

“Wander”

Simulation & Comparative Testing• Based on 87 vehicle evaluations, Toyota set up a test vehicle

• Test vehicle was configured with steering and suspension components considered 3 standard deviations from normal production to represent the most extreme case for stiff steering feel from a design point of view

• The test vehicle was evaluated dynamically to assess steering effort

and stability

• Steering angle and vehicle direction were evaluated against road undulations and compared to other vehicles

• Test vehicle compared favorably to other models evaluated

Simulation & Comparative Testing

Confidential Information Redacted

Simulation & Comparative Testing

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Simulation & Comparative Testing

Confidential Information Redacted

Toyota Assessment• Corolla steering is stable and controllable

• “Wander” or “Drift” is perceived by some drivers due to slightly stiff steering “feel” in the on-center position

• Steering effort and feel is comparable to a variety of other vehicles

• Steering “feel” may be “different” from customer’s previous experience, but is no different than the feel of driving a different vehicle than usual (e.g. a rental vehicle)

Toyota Assessment• No defect is present in the EPS system

• The design and performance of the EPS are appropriate and no unreasonable safety risk is presented

• This is a customer satisfaction issue that will be addressed by a differently calibrated EPS ECU for those owners who prefer a “lighter” steering feel

Vehicles Available to Drive• Test vehicle (described above)

• Repurchased vehicle

• Toyota purchased the vehicle (ODI # 10308501) from a customer who complained of “touchy” steering and experienced

vehicle “wander” on the freeway

• The customer primarily operated the vehicle in the Sacramento, CA area and perceived a “wander” at speeds above 45mph

• Customer submitted VOQ after learning from a news story that “this is a real safety issue, coupled with the gas pedal issue”

• Toyota evaluated the vehicle and found no defect present in the

EPS system