Here's a breakdown of how to approach this problem:
1. Identify the Vacuum Source:
* Vacuum Pump: Your truck likely has a vacuum pump driven by the engine. This is the most common source of vacuum. Check its condition – is it making noise? Is it leaking? It's usually located near the engine and often attached to the engine block or transmission.
* Manifold Vacuum: Some systems might tap into manifold vacuum, but this is less common for power steering and transmission functions in heavier-duty trucks.
2. Check for Obvious Leaks:
* Visually inspect all vacuum lines: Look for cracks, holes, or loose connections. Pay close attention to lines running to the brake booster, power steering pump (if vacuum-assisted), and transmission (if vacuum-operated shifting). Use a shop light to help you see in tight areas.
* Listen for hissing: With the engine running (at idle), carefully listen for hissing sounds near vacuum lines. This indicates a leak. Spraying soapy water onto the lines can help locate leaks—bubbles will form at the leak point.
3. Test the Vacuum Pump (if you can access it):
* Use a vacuum gauge: Connect a vacuum gauge to the vacuum pump output and check the vacuum reading while the engine is running. A low reading or no reading indicates a pump failure. The specific reading will depend on the engine's RPM, but it should be substantial (typically above 15 inches of mercury).
4. Check Vacuum Reservoirs (if equipped):
* Some systems might incorporate vacuum reservoirs to smooth out fluctuations. If your truck has one, check its condition and level.
5. Where to Find a Diagram (Difficult but Possible):
* Factory Service Manual: The most reliable source. A Haynes or Chilton manual *might* have a simplified diagram, but a factory service manual is the best bet. You might find a digital copy online or through a parts store. The manual will show the specific routing of the vacuum lines and the components they connect.
* Online Forums: Search specific forums dedicated to Dodge Ram trucks (like RamForum.com or similar forums). Someone there might have a diagram or be able to help you identify the problem based on your description.
Important Considerations:
* Safety First: Working on a vehicle's braking and steering systems requires caution. If you're not comfortable working on your truck, take it to a qualified mechanic.
* Transmission Issues: The transmission not shifting is a serious issue and could indicate something beyond just a vacuum problem. This could be a more significant mechanical or electrical failure.
* Power Steering: While some older trucks use vacuum-assisted power steering, many modern heavy-duty trucks utilize hydraulic power steering. Double-check if your truck's power steering uses vacuum.
Lack of vacuum in multiple systems simultaneously strongly suggests a problem with your vacuum pump or a massive leak. Start with the visual inspection and listen for hissing sounds. Using a vacuum gauge will give you a clearer picture of whether your vacuum pump is functioning correctly.
