1. Transfer Case Issues:
* Transfer Case Lever/Selector: Ensure the transfer case lever is correctly positioned in 4H (4-wheel high) or 4L (4-wheel low). A worn or damaged linkage could prevent proper engagement. Inspect the linkage for bending, broken parts, or loose connections.
* Transfer Case Motor (if equipped): Some 1995 Rams might have an electric motor for the transfer case shift. A faulty motor or its associated wiring could prevent engagement. This requires checking for power at the motor and testing the motor itself.
* Internal Transfer Case Problems: This is a more serious issue. Low fluid, worn components (chains, gears, bearings), or a broken part inside the transfer case can prevent 4x4 from engaging. This often involves a noise (grinding, whining) when attempting to engage 4x4. A professional inspection is needed.
2. Front Axle Issues:
* Front Axle Disconnect (if equipped): Some systems have a disconnect in the front axle to allow for 2WD driving. This could be stuck in the disengaged position. Check for vacuum lines (if present) and make sure they are intact and not leaking. Listen carefully near the front axle for any clicking or other sounds when attempting to engage 4x4.
* Front Axle Hubs (automatic hubs): Automatic locking hubs require vacuum or electric power to engage. A problem with the vacuum system (leaks, faulty solenoid) or electrical system (wiring, switch, motor) can prevent the hubs from locking. Manual locking hubs require manual engagement and disengagement.
* Front Driveshaft: A broken or disconnected front driveshaft will prevent 4x4 from working. Check the U-joints, slip yoke, and for any obvious damage or disconnections.
3. Electrical Issues:
* 4x4 Indicator Light: Is the 4x4 indicator light on the dash illuminating correctly when you select 4x4? If not, there’s likely an electrical problem preventing the system from engaging. This could be a faulty switch, wiring harness problem, or a relay issue.
* Fuse/Relay: Check the fuses and relays related to the 4x4 system in the fuse box.
4. Other Potential Causes:
* Low Transfer Case Fluid: Low fluid level can severely damage the transfer case. Check and add fluid if necessary. Use the correct type of fluid specified in your owner's manual.
* Binding or Obstructions: Something might be obstructing the engagement of the 4x4 system. This is less likely but possible.
Troubleshooting Steps:
1. Check the transfer case lever: Make sure it's in the correct position and that the linkage operates smoothly.
2. Inspect the 4x4 indicator light: Does it illuminate correctly? This gives a clue about electrical problems.
3. Check the fuses and relays: This is a quick and easy first step.
4. Listen for unusual noises: Grinding, whining, or clicking sounds indicate mechanical problems.
5. Check fluids: Make sure transfer case and differential fluids are at the correct levels.
When to Seek Professional Help:
If you're not comfortable working on your vehicle's drivetrain, or if you've checked the easy things and still can't figure out the problem, take it to a qualified mechanic familiar with 4x4 systems. Incorrect diagnosis and repair can lead to expensive damage. Mentioning the specific symptoms and your preliminary checks will help the mechanic diagnose the problem more efficiently.
