A significant number of posts on this forum are related to noises and sounds that an owner's Volt might be making. As most everyone here knows, there is quite a list of unique and often normal sounds that the Volt I will exhibit during normal operation, as well as when the car is OFF or charging. Many of these sounds or noises are unique to the Volt and are the result of it's unique EREV powertrain and plug-in capabilities.
My intention here IS NOT to list every possible noise ever observed but instead specific noises/sounds that GM has offically documented as either "normal" or "abnormal" with explaination and potential cause-corrective measures if/when provided.
The chosen definition of various noises can also vary somewhat so some varition in terms can be expected (eg "chattering" vs. "clicking")
I will try to maintain this "pinned" list of GM preliminary product bulletins relating to noises or sounds (both normal and abnormal) as new bulletins are released.
Please note that while providing the bulletin number to your dealer might be useful in reaching a resolution more quickly, there can of course be other causes for ANY noise than documented here.
Also note that some bulletins are model year or even VIN specific. This does not neccessarily mean that any paticular noise bulletin may not potentially still apply,(should you be outside of these parameters) just that GM has specifically identified them as such.
Any questions feel free to post here and myself or others (with their own experience to share) will try to answer
Bulletin List as of 5/5/2012
PI0307: Volt New Model Features and Service Guide- 2011-2012 Chevrolet Volt
Unique Characteristics and Normal Operating Conditions- Drivers of the Chevrolet Volt may experience some operating characteristics that are unique to this vehicle. Due to the quiet nature of the VOLTEC Propulsion system, certain sounds that may have been masked by the engine's natural harmonics will be apparent. Among them is the electric engine cooling fan, coolant pumps, the air conditioning compressor and the HVAC blower. In addition to those sounds, the drive motor battery cooling system may be operational during charging or when the vehicle is powered down.
Brake Pedal Feel and Brake Pedal Vibration- The Volt has a unique brake pedal feel. This is because the hydraulic system is not the lone provider of vehicle deceleration. The electric system blends in regenerative and hydraulic braking forces depending upon vehicle conditions. Over several braking events, the customer may perceive that they are applying a consistent brake force and yet the vehicle may decelerate at slightly different rates. This is a normal operating characteristic to maximize fuel economy. The Volt utilizes a braking system that employs a high-speed electric motor/pump. Pump operation can sometimes be heard and felt in the brake pedal as the system sometimes builds pressure.
Air Conditioning- The Volt has a 300V A/C compressor that can be operated even when the range extender engine is off or during periods where the vehicle is charging. The A/C compressor is serviced as a unit, and uses POE (Polyol Ester) refrigerant oil instead of PAG (Polyalkylene Glycol) because it is less hygroscopic. The A/C compressor features a high RPM scroll compressor that is pulse width modulated. During conditions with high ambient temperatures and high humidity, the driver may notice a unique high-pitched sound from the compressor. This is considered a normal characteristic, and it may be heard when the vehicle is stopped or at low speeds.
Whine Sound During Electric Operation- Due to the electric nature of the vehicle, the electric motor may be heard as the vehicle moves. This is a normal operating characteristic.
PI0409: Rattle Noise from Right Front of Vehicle While Driving - 2011 Volts
Some customers may comment on a rattle or flutter type noise coming from the right front of the vehicle while driving. This condition is most apparent when driving at highway speeds (over 80 km/h (50 mph).This condition may be caused by the front wheelhouse rear liner being loose at the bottom. The push-in retainer that fastens the wheelhouse liner may be loose or missing. This will allow the wheelhouse liner to rattle against the body.
PI0435: Buzz Type Noise from Instrument Panel when Operating HVAC System - 2011 Volts
Some customers may comment on a buzz type noise coming from the lower center area of the instrument panel while operating the Heating Ventilating Air Conditioning (HVAC) system fan.This condition may be caused by insufficient lubrication on the HVAC mode control cam actuator gear.
PI0478: Creaking Noise Coming from Front Door Glass - 2011-2012 Chevrolet Volt
Some customers may comment on hearing a creaking noise coming from the front door glass after the window switch is released and/or the glass movement has stopped after raising/lowering the glass. Excessive dirt can accumulate between the glass and the glass run channel seals. This may vary with customer driving environment.Repair Instructions: Thoroughly clean the glass and glass run channels at the B-pillar.(with instructions)
PIC5412: High-Pitched / Whine Noise Heard Intermittently From Behind Rear Seats - 2011-2012 Chevrolet Volt
Some customers may comment on hearing a high-pitched whine noise during braking or accelerating, mostly in Extended Range Mode with the engine running. If a customer is experiencing a high-pitched whine noise from the rear of the vehicle, check the load floor, in the rear of the vehicle, for being not properly secured. Also insure the 120-volt portable charger has been correctly stored face down and tightly wrapped to ensure the rear compartment lid will completely close and secure magnetically to prevent unwanted noises from entering the cabin. Repair instructions:Inspect for front of rear load floor not properly secured, check rear of hatch lid for complete closing and magnetically "latching".
PIP4870: (EREV) Engine Or Exhaust Noise While Driving In Extended Range Mode -2011-2012 Chevrolet Volt
Some customers may comment that the engine noise is sometimes louder than expected. This document will explain known normal and abnormal reasons why the engine may be louder in some conditions and vehicles during Extended Range driving.Various repair procedures if determined to be abnormal.
PI0642: Wind Buffeting (Noise) when Power Windows Operated - 2011-2012 Chevrolet Volt
Some customers may comment on a wind buffeting type noise when any of the power windows are operated. This condition can be heard while driving with any or all of the power windows down.
This condition is a result of the aerodynamically optimized vehicle exterior design. This design maximizes the electric and fuel efficiency of the vehicle.Repair procedure may require installation of mirror skull-cap kit.
PI0659: Groan, Squeak or Rubbing Type Noise When Turning Steering Wheel - 2011-2012 Chevrolet Volt
Some customers may comment on a rubber squeak type noise when turning the steering wheel. This condition may be caused by the seal for the intermediate shaft, located at the front of dash, being out of position and rubbing on the rotating intermediate steering shaft.Repair procedure may require repositioning of intermediate shaft boot/seal.
Campaign 12020: Customer Satisfaction - Driver Airbag Inspection - Certain 2011-2012 Volts
(call you dealer with VIN to check/confirm existing status)
Certain 2011-2012 model year Chevrolet Volt vehicles may have a condition in which the driver airbag module retainers may not be fully engaged in the steering wheel due to an interference condition with a felt insulator patch. This condition may cause possible squeaks and rattles but does not affect the function or operation of the airbag. The airbag will deploy as designed.Repair instructions include removing the driver airbag module from the steering wheel and inspecting and if necessary relocating the position of this felt patch.
PI0634: Rattle Type Noise Heard from Front of Vehicle at Slow Speeds- 2011-2012 Chevrolet Volts Built Prior to September 20, 2011
Some customers may comment on a rattle type noise coming from the front of the vehicle at low speeds over bumps. This noise may be caused by the front brake pads rattling against the caliper. Repair procedure may require addition of anti-rattle kit.
PI0645: Knock or Pop Noise Heard When Coming to a Stop or at Low Speeds Over Small Bumps - 2012 Chevrolet Volt built prior to CU113841
Some customers may comment on a knock or pop noise heard from the front strut assembly when coming to a stop or at low speeds over small bumps in the road. Repair procedure may require replacement of front struts.
PSB#12-03-08-001: Clunk or Thump Type Noise from Front Suspension (multiple models including 2011-12 Volt)
Some customers may comment on a clunk or thump noise coming from the front suspension while driving over rough road surfaces. This noise will typically occur when the front suspension is returning to the upward position after a hard downward stroke, such as after driving through a large rut or pothole.This condition may be caused by the jounce bumper slamming into the upper spring seat because it is not retained in the correct up position. The jounce bumper loses position due to oil being deposited onto its retention fingers. The oil is from the strut leaking.Correction- Inspect the front strut(s) for evidence of oil. The leak may be slight but will still cause the concern. If oil is present, replace the affected strut, jounce bumper and dust boot (shield). Before reassembling the strut assembly, glue the new jounce bumper and new dust boot (shield) to the upper spring seat using the steps listed below. To further confirm this concern, the shield/bumper will easily slide up and down the strut shaft.
PI0795: Clunk Noise When Applying Park Brake 2011-2013 Chevrolet Volt
Some customers may comment on a noise when activating the park brake.
This noise may be due to an excessive gap between the park brake cable and the bracket hole. The cable would move and bind inside the hole and make a noise.The noise may be remedied by placing rubber washer/s on one or both park brake cables at the bracket.
PIC5734: Pulsation Or Drumming Noise Felt Through Brake Pedal On Light Apply 2011 - 2012 Chevrolet Volt (*2013 models currently still pending)
Some customers may experience a drumming/ ringing like noise after depressing the brake pedal. This phenomenon is typically most noticeable during low speed EV Driving and or stationary brake pedal applies while in Park. There may also be an abnormal pulsation felt through the brake pedal while sitting still with your foot slightly depressing the brake pedal. The noise presents itself as a hydraulic pressure related drumming or ringing sound that tends to transmit throughout the entire vehicle. This noise may also be heard immeidately after the vehicle is powered off.