* Shared Power Source: Many vehicles, including Astro vans, use the power steering pump to provide hydraulic pressure. This pump is driven by the engine's accessory belt. If the pump fails, it loses the ability to provide power assistance to both the steering and the brakes (if the brakes are hydro-boost).
* Hydro-Boost Brakes: Astro vans, particularly older models, often utilize a hydro-boost brake system. This system uses the power steering pump to assist in braking, supplementing driver effort. A failed power steering pump means no hydraulic assistance for the brakes. This results in extremely difficult, or even impossible, braking.
* Belt Failure: A broken or severely slipping serpentine belt (the belt that drives the power steering pump and other accessories) could also cause both systems to fail simultaneously. This is because the pump wouldn't be turning.
* Low Hydraulic Fluid: While less likely to cause a complete failure of both systems *simultaneously*, extremely low power steering fluid can impact both systems. The pump might cavitate (sucking air instead of fluid), resulting in a loss of pressure.
Other, Less Likely Possibilities:
* Major Hydraulic Leak: A significant leak in the power steering system could drain fluid quickly, affecting both steering and brakes (if hydro-boost). However, this would usually show other warning signs beforehand (like fluid leaks).
* Electrical Failure (less likely): While less common, an electrical fault affecting the power steering pump's motor or the hydro-boost system could theoretically affect both. This would be a more complex issue.
In summary: The most probable cause of simultaneous power steering and brake failure in a Chevy Astro van is a faulty power steering pump or a broken serpentine belt. It's crucial to have the vehicle inspected by a mechanic immediately as it's unsafe to drive.
