For 1990-2009 cars

# Information on Optimized Hydraulic Boost Brake System Characteristics

Subject: | Information on Optimized Hydraulic Boost Brake System Characteristics

Models: | 2008 Pontiac Solstice GXP

| 2008 Saturn Sky Redline

| 2008 Opel GT

| with 2.0L Engine (VIN X - RPO LNF)

The Optimized Hydraulic Boost (OHB) is a standard feature, included with all 2008 vehicles equipped with the 2.0L (RPO LNF) engine). OHB assists brake operation under low engine vacuum conditions using the ABS system.

If your vehicle has Electronic Stability Control (ESC) and the 2.0L turbocharged engine, it will also have a hydraulic brake boost feature which supplements the power brake system to maintain consistent brake performance under conditions of low brake booster vacuum utilizing the ABS system.

Important: Increased brake pedal effort due to low brake booster vacuum conditions may exist during;

• | The initial cold engine start up and the first few brake applies.

• | When the vehicle has been parked for extended periods and/or at higher altitudes and restarted.

• | Any time the vehicle is started up after a brake booster has been completely bled down (no stored vacuum).

The OHB functions are controlled by the Electronic Stability Control (ESC) Module. The ESC module determines when to activate the OHB.

The following OHB characteristics are considered to be normal:

• | Increased brake pedal effort under low brake booster vacuum.

• | Change in brake pedal effort when OHB is active.

• | Ratchet sound coming from the brake system during OHB activation.

• | Frequent brake stops may result in OHB activation.

• | High altitude driving may result in OHB activation.

• | Brake pedal movement or pulsation when the OHB is active.

Some customers may bring their vehicle back to the dealership commenting on any or all of the above characteristics . The customer may experience brake pedal movement or pulsation accompanied by a change in brake pedal effort when the OHB is active.

Important: Do not attempt to repair or replace any parts for what is considered normal operation of the OHB.

If a condition should exist in which you might not be receiving the intended brake boost, the SVC BRAKE SYSTEM message may be displayed on the DIC.