(Hybrid) Additional Information On Bleeding The Brakes - keywords bleed 2-mode DTC electrical hp2 mode two two-mode
| Subject: | (Hybrid) Additional Information On Bleeding The Brakes |
| Models: | 2009 Cadillac Escalade Hybrid |
| 2008-2009 Chevrolet Tahoe Hybrid |
| 2008-2009 GMC Yukon Hybrid |
| with Two-Mode Hybrid System (RPO HP2) |
This PI was superseded to update models and model years. Please discard PIT4597.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
The following steps are needed to help perform a successful brake bleed on the Two Mode hybrid. The 2 Mode braking system is unlike most traditional hydraulic brake systems. It is very important for proper brake system performance to follow the brake bleeding procedure exactly. Air trapped in the brake system will cause performance problems and DTCs without the symptoms of a spongy or low brake pedal. If you miss a step in the brake bleed procedure, you must start over at step 1 without exception.
Recommendation/Instructions:
- Install the midtronics battery charger on the vehicle to maintain battery voltage.
- Use a pressure bleeder that is capable of delivering 30 psi for the entire bleed procedure. Failure to provide a constant 30 psi will cause air to be trapped in the brake system and may cause brake performance problems or DTCs to occur. Tool J-29532-A has been tested extensively on this application and has proven to provide the necessary pressure and volume of brake fluid. Vacuum bleeding and other brake bleeding tools are NOT acceptable for this procedure.
- Step 37 of the brake bleed procedure (Document Id: 1998764) describes loosening one of the 2 intermediate brake pipe fittings. The following photo labels the lines at the master cylinder.
Note: The dealership must use a J-29532-A pressure bleeder or a diaphragm type (ball bleeder) pressure bleeder in order to perform the hybrid brake system bleed procedure. A replacement J-29532-A can be ordered from 1-800-GM-TOOLS.
ARROW 1 points to the front brake lines
ARROW 2 points to the Intermediate lines
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
