Tech Tip: Cadillac brakes lock up after fluid top-off

April 29, 2022
The owner of this CTS said that the brakes locked up and wouldn't release. The problem occurred after he topped off the brake fluid.

Vehicle: 2008 Cadillac CTS, RWD, V6-3.6L, Automatic Transmission/Transaxle

Mileage: 168,265

Problem: The owner of this CTS said that the brakes locked up and wouldn't release. The problem occurred after he topped off the brake fluid.

Case Details: The technician’s initial checks found that the brake fluid looked contaminated with debris floating in it. The master cylinder cap seal was swollen, and master cylinder appeared to have been leaking onto the booster. An ALLDATA Tech-Assist consultant recommended finding out what kind of fluid the vehicle owner used. If it was anything other than an approved brake fluid, then everything in the brake system with rubber in it (hoses, calipers, master cylinder, ABS module, etc.) would need to be replaced, and the hard lines flushed. A call to the owner revealed that he had topped up the brake fluid reservoir with power steering fluid.

Confirmed Repair: The technician replaced the master cylinder, calipers, rubber hoses, and flushed the entire brake system, including the ABS components. A lengthy road test verified the repair.

Reprinted with permission from ALLDATA

Sponsored Recommendations

Access Carside OEM Repair Data with MOTOR TruSpeed

Now available on all Autel MaxiSYS Ultra Series tools, MOTOR TruSpeed Repair delivers expanded OEM service and repair data within days of being published by

ADAS Case Study: From 10 Calibrations a Month to Over 10 A Day

Originally published by Vehicle Service Pros, March 26, 2024

Ask The Expert: The Basics & Benefits of Bringing ADAS Calibrations In-house

Originally published by Vehicle Service Pros, March 26, 2024

Simplifying the ADAS Opportunity

Originally published by Body Shop Business, February 12, 2024

Voice Your Opinion!

To join the conversation, and become an exclusive member of Vehicle Service Pros, create an account today!