A few days ago, a light came up on my 2000 GMC Sierra that said something like ABS Pressure, though I only caught a glimpse of it before my truck broke down. The truck started back up a few moments later, with some serious brake issues. Depressing the brakes to the metal barely slows the truck down. I checked the fluid, and there was very little in the reservoir, so I will obviously fill it up and hope for the best. My question is why did the truck shut off, but now starts up fine? Is that a failsafe? And how do I know if it isn‘t just a lack of fluid but possibly a master cylinder or worse issue?Thanks for any help!
Too late now! Take the truck to a GMC or Chevrolet dealer and ask them to CHANGE the brake fluid and pressure bleed the brake system. Your 13 year old truck's brake system is loaded with water!
The diaphram in the booster is leaking and the truck shuts off when you have an air leak that's beyond acceptable limits. However, because you master cylinder was low on fluid too that indicates either a lot of brake pad wear or a leak, could be either one or both.
One thing is certain, if there was an extremely low level of fluid in the master cylinder there's s leak. no other explanation. When a brake system runs out of fluid you can't just refill it and expect the brakes to work properly. Once the fluid is run out air enters the system and braking systems can't work with air in it. First you have to locate the leak, repair it and then refill the master but the system must be bled to remove that air before its safe to drive. You find where the fluid leaked out and you've found the cause of the ABS warning light. Off hand the only reason I can think of that the engine may have shut down was due to a bad brake booster malfunction caused by the vacuum leak. I don't think there's a fail safe for that condition on any cars.
