Two problems related to brake master cylinder have been reported for the 2003 Cadillac CTS. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2003 Cadillac CTS based on all problems reported for the 2003 CTS.
This morning when I backed my Cts out of the parking spot to go to work I noticed the brakes were a little soft. I then parked the car and opened the hood to look at the brake fluid reservoir and noticed it wasn't completely full but there was still a sufficient level of fluid. I then looked at the ground and noticed a line of liquid that traced my movement backwards out of the parking spot and then back into the parking spot, this liquid was brake fluid. Imagine my surprise at having a second gm vehicle with a brake line failure 30 days after experiencing a brake line failure for the first time in my 40+ years of driving and owning vehicles. The first was a 2001 tahoe which I reported last month to NHTSA and which cost me over $1,000 to replace all of the brake lines. After work this evening I examined the Cts and discovered extreme corrosion in the two brake lines running from the master cylinder to the abs unit in the front of the engine bay. The corrosion is worst where the lines run behind the radiator and it appears both lines have failed. The lord must have been looking out after me because last night I drove 37 miles from baltimore on the interstate. Had the brakes failed then I imagine I would have been in a spectacular accident on I-95 that may have taken my life as well as others. Gm recalled the Cts for brake line corrosion by the calipers where the line connects inside a rubber piece. Nhtsa is investigating brake line corrosion on 1999 to 2003 full size gm trucks and pickups and I suggest the investigation be expanded to include all gm vehicles of this vintage as it appears gm used an inferior grade of steel in their brake lines in all of the vehicles.
I have a 2003 Cts since new. The brakes almost completely failed last week. No dash light came on. The problem is easily seen. One of the lines from the master cylinder going to the abs unit badly corroded at the lowest point in its run where the line is supported. The line away from the support is in good shape so it looks like you have a design flaw or improperly implemented design with that support. I was extremely lucky and extremely disappointed. The car has never been in an accident and most of the underside body and hardware looks almost new. My dealer says they have replaced a number of Cts brake lines. You have a problem I had a lot of trouble with the Cts when it was new as you should be able to see from your records. Although replaced the rear differential still howls. I expected better from Cadillac. With that said I think gm ought to do something about the Cts brake lines.