Here's what's likely happening and what needs to be checked:
* Low Clutch Fluid: This is the most likely culprit. Check the clutch fluid reservoir (usually a small, separate reservoir, not the brake fluid reservoir). If it's low, you'll need to find and repair the leak. Simply adding fluid is a temporary fix; you must address the leak.
* Leaking Slave Cylinder: This is a common point of failure in hydraulic clutch systems. The slave cylinder is located at the transmission and pushes the clutch fork. A leak here prevents the clutch from disengaging fully.
* Leaking Master Cylinder: Located near the clutch pedal, this cylinder pushes the fluid to the slave cylinder. A leak here will have similar effects to a leaking slave cylinder.
* Air in the Hydraulic Line: Air in the hydraulic lines can prevent proper clutch operation. This often manifests as a spongy pedal, but could also contribute to a pedal that stays down. Bleeding the clutch system might resolve this, but only if there isn't also a leak.
* Damaged Clutch Disc or Pressure Plate: While less likely to cause the pedal to stay down *by itself*, a worn-out or damaged clutch disc or pressure plate can make it hard to shift, especially into reverse, and could contribute to the feeling of a problem with the hydraulics.
What you should do:
1. Check the Clutch Fluid Reservoir: Immediately check the fluid level. If low, add DOT 3 or DOT 4 brake fluid (check your owner's manual to be sure). *Do not overfill.* This is a temporary measure to allow you to drive it to a mechanic, but *do not* drive it for long distances if there is a leak.
2. Inspect for Leaks: Carefully examine the clutch lines, master cylinder, and slave cylinder for any signs of fluid leaks. Look for wet spots, drips, or fluid residue.
3. Get Professional Help: This is not a DIY job for most people. A stuck clutch pedal could indicate a significant problem that requires professional diagnosis and repair. Take your truck to a qualified mechanic. Attempting repairs without the proper knowledge and tools could lead to further damage and potentially expensive repairs.
Ignoring the problem could lead to complete clutch failure, leaving your truck immobile. Have it checked promptly.
