NHTSA ID Number: 10046339
Manufacturer Communication Number: PI-0785
TSB/Document Date: 2012-10-11
Summary
BUICK
/CADILLAC/CHEVROLET/GMC: MASTER CYLINDER WAS UNBOLTED FROM BRAKE BOOSTER AT TIME OF APPLYING BRAKES WITH BRAKE PEDAL, THAT WAS LOW AND POSSIBLE CAUSE WAS SMALL VACUUM LEAK BETWEEN MASTER CYLINDER AND BRAKE BOOSTER WAS FOUND. CERTAIN MODELS 2009-2013 OF BUICK, CHEVROLET, CADILLAC, GMC. *PE UPDATED 10/15/12. *PE
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- SB-10046339-3324.pdf (76.20 KB)
- SB-10046339-5768.pdf (109.10 KB)
- Mixes well with conventional fluids
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TSB/Document ID: PI-0785
Replacement Service Bulletin Number: PI-0785-A
MFR Communication Date: 2012-08-01
MFR Internal Campaign ID/Software Version:
Communication Type: Service Bulletin/Repair Instructions
NHTSA Components: SERVICE BRAKES, HYDRAULIC:PEDALS AND LINKAGES
MFR Component System:
MFR Component Subsystem:
Previous TSB | Next TSB |
SB-10046339-3324
File in Section:
Service Bulletin
Bulletin No.:
Date:
PI0785
August, 2012
PRELIMINARY INFORMATION
Subject:
DTC C027B, Low Brake Pedal Feel After Master Cylinder Repairs
Models:
2009-2013 Buick Enclave
2010-2012 Buick LaCrosse
2011-2013 Buick Regal
2012-2013 Buick Verano
2009-2013 Cadillac CTS, SRX
2013 Cadillac ATS, XTS
2009-2012 Chevrolet Colorado
2009-2013 Chevrolet Corvette, Impala, Malibu, Traverse
2010-2013 Chevrolet Camaro, Equinox
2011-2013 Chevrolet Cruze
2012 Chevrolet Captiva Sport
2012-2013 Chevrolet Sonic
2013 Chevrolet Spark
2009-2012 GMC Canyon
2009-2013 GMC Acadia
2010-2013 GMC Terrain
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern
Some customers may comment on a low brake pedal during brake pedal apply. During diagnosis, a DTC C027B may
be found stored in the EBCM. This concern may have started after the master cylinder was unbolted from the brake
booster for any reason.
This may be caused by a small vacuum leak between the master cylinder and the brake booster. There is an O-ring
between the master cylinder and the brake booster that may have fallen off during the prior repairs.
Recommendation/Instructions
2515865
Inspect for the O-ring (1) between the master cylinder and the brake booster before performing any other diagnostics
for the low brake pedal or the DTC C027B. Replace the O-ring if missing or damaged.
Tip: Exhaust the booster vacuum by either pumping the brake pedal or pulling the check valve out prior to removing
the master cylinder. The suction may be helping to dislodge the O-ring when pulling the master cylinder out.
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.
Part information
Refer to the Parts Catalog for the appropriate part number and availability.
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation
Description
Labor Time
H0640*
Replacing the Brake Master Cylinder O-ring Seal
0.3 hr
H0640**
Master Cylinder Replacement
Use Published
Labor
Operation Time
*This is a unique labor operation for bulletin use only. It will not be published in the Labor Time Guide.
** Vehicles that come without O-ring seal separate from master cylinder.
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