Serious Flaw W/GMC 2003 Pick-up

I simultaneously loss my power steering and power brakes.

I have a 2003 GMC crew cab with the Duramax diesel. I started the truck in the drive and noticed I couldn't turn the steering. Thinking that the wheels may be obstructed by something I put the truck into drive to move it a few feet forward to see if that fix the problem and that's when I noticed that the brakes would just barely stop the truck's forward motion.

I had the truck towed in to my GMC dealer for repair. The technician at the dealer said that on my year truck the power brakes are hydraulic assist and the assist comes from the power steering pump. Apparently there is a valve in the pump that when it becomes obstructed you loose both power steering and power brakes. The recommended fix was to flush the power steering system and replace the hydraulic fluid. I'm not convinced that's the correct fix.

I've notified GM and the NHTSA via letter of this incidence.

Can this problem happen while you're driving down the road? I'm going on the assumption that it can, so take care.

Reply to
Greg Downer
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This is not unheard of, although it is fairly uncommon and it's not only a GM problem. This could happen on any truck with hydraulic assist brakes if you get a blockage in the valve, or if you break your fan belt on your power steering pump, or if you run the power steering pump dry. On some of the older Ford diesels I used to drive in the Fire Dept. the brakes were still vacuum assisted so the truck had a vacuum pump. If that pump failed, got clogged, or you broke the belt on it then you would lose your brakes as well.

Did you check with

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to see if there were any recalls, safety notices or frequent complaints about this for your truck?

Cheers - Jonathan

Reply to
Jonathan Race

This "might" apply to your vehicle.

F/CMVSS Noncompliance - Brake Hydro-Boost Relief Valve Seal Fracture #04004A - (Jun 18, 2004)

04004A - Brake Hydro-Boost Relief Valve Seal Fracture 2003-2004 Cadillac Escalade, Escalade EXT, Escalade ESV 2003-2004 Chevrolet Silverado, Avalanche, Suburban, Express 2004 Chevrolet Tahoe 2003-2004 GMC Sierra, Yukon, Yukon XL, Savana 2003-2004 HUMMER H2

THIS BULLETIN CANCELS AND REPLACES BULLETIN 04004, ISSUED JUNE 2004. THE INSPECTION PROCEDURE IN THIS BULLETIN HAS BEEN REVISED TO INCLUDE ADDITIONAL STAMPED NUMBERS ON THE HYDRAULIC BRAKE BOOSTER. ALL COPIES OF BULLETIN 04004 SHOULD BE DESTROYED.

Condition General Motors has decided that certain 2003 and 2004 model year Cadillac Escalade, Escalade EXT and Escalade ESV; Chevrolet Silverado, Avalanche, Suburban, and Express; GMC Sierra, Yukon, Yukon XL, and Savana; HUMMER H2; and 2004 model year Chevrolet Tahoe vehicles fail to conform to either Federal/Canada Motor Vehicle Safety Standard 105, "Hydraulic and Electric Brake System", or Standard 135, "Light Vehicle Brake Systems". These vehicles may have a relief valve bore within the brake hydro-boost module that is not to specification. An out-of-specification bore could result in fracture of the relief valve o-ring seal within the module. If this happens, during brake applications the driver may be able to hear an engine compartment noise similar to the sound that occurs when the steering wheel is turned to a full stop position. The driver could also experience a slight increase in steering efforts while braking and parking. Under certain driving conditions, a fractured seal may require a slight increase in the applied brake pedal effort to achieve the same vehicle deceleration rate as prior to the seal fracture. If this were to occur, it could result in a vehicle crash without prior warning.

Correction Dealers are to inspect the hydro-boost module and replace the relief valve, if necessary.

Ian

Reply to
shiden_kai

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