07-05-25-007B: Pedal Noise/Buzz, Extra Effort Needed to Depress Brake Pedal After Vehicle Has Not Been Driven For Extended Period of Time (Reprogram ECM and ECM) - (May 16, 2008)
Models: 2008 Pontiac Solstice GXP
2008 Saturn SKY Redline
2008 Daewoo G2X
Built Prior to the Breakpoints Listed Below
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This bulletin is being revised to announce that the calibrations are available for vehicles equipped with manual transmissions. Please discard Corporate Bulletin Number 07-05-25-007A (Section 05 -- Brakes).
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Model-VIN Breakpoint
Saturn-8Y129355
Pontiac-8Y129363
Daewoo-All Vehicles
Please make a copy of this bulletin and give it to your customer for future reference.
System Description
The 2008 Pontiac Solstice GXP, Saturn SKY Redline, and Daewoo G2X are performance vehicles that come equipped with the 2.0L (RPO LNF) engine and an advanced performance braking system called Optimized Hydraulic Boost (OHB). The OHB brake system utilizes the Anti-Lock Brake System (ABS) to assist vehicle braking in low brake vacuum conditions.
The brake systems on these vehicles use engine vacuum to assist the power brake system during most brake applications. The OHB system supplements the power assist brake system when there is low engine vacuum, such as when the engine is initially started after an extended period of no operation or while operating in high altitude.
Condition
Some customers may comment on one or more of the following brake system characteristics:
• Increased brake pedal effort due to low brake booster vacuum conditions that may occur after the vehicle has not been operated for an extended period of time and/or at higher altitudes and restarted.
• Brake pedal movement or pulsation accompanied by a ratchet sound coming from the brake system during OHB activation when braking.
Correction
Reprogram the ECM with an updated engine calibration. This new service calibration will increase engine vacuum when the vehicle is initially started.
Reprogram the EBCM with an updated brake calibration. This programming event will return the module to its original state if it was previously updated for this condition.
These calibrations will be available as an EBCM/ECM programming sequence event. From the controller list, select "EBCM/ECM Sequential Program."
Important:
• After the EBCM/ECM calibration, brake pedal movement or pulsation accompanied by a ratchet sound will be reduced.
• Allowing the engine to idle for a period of time after the engine is started will help increase the vacuum for the power assist brake system.
• If the SVC BRAKE SYSTEM message is displayed on the DIC. The brake system must be inspected for any faults in the system.
Refer to the Owner Manual (page 4-4 for the Pontiac Solstice or Saturn SKY) for additional information on this brake system operation.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
The recalibration is covered under the New Vehicle Limited Warranty for 36 months or 36,000 miles, which ever comes first
