1. Parking Brake Adjustment:
* Issue: The most common culprit is the parking brake (emergency brake) being too tight. Even a slightly over-adjusted parking brake can drag on the rear drums or rotors, preventing them from releasing fully.
* Troubleshooting: Locate the parking brake adjustment mechanism (usually a cable with a star-wheel adjuster near the rear wheels or under the rear seat). Slightly loosen the adjuster. Test the parking brake to ensure it still holds adequately. Repeat the process until the rear brakes release freely. *Important: If you're unsure how to adjust the parking brake, consult a repair manual for your specific Ranger model.*
2. Brake Shoes or Pads Sticking:
* Issue: Brake shoes (drum brakes) or pads (disc brakes) can stick due to corrosion, rust, debris, or damage to the caliper or wheel cylinder.
* Troubleshooting: This requires more hands-on work. You'll need to remove the wheels and inspect the brake components. Look for rust, corrosion, or anything that might be preventing smooth movement. Clean thoroughly and use a brake parts cleaner. If there's significant damage, you'll need to replace the affected parts.
3. Wheel Cylinders (Drum Brakes) or Calipers (Disc Brakes):
* Issue: Leaking wheel cylinders (drum brakes) or calipers (disc brakes) can cause the pistons to remain partially extended, keeping the brakes engaged. Internal seals may be worn or damaged.
* Troubleshooting: Inspect the wheel cylinders or calipers for leaks. Look for brake fluid leaking around the pistons or any obvious damage. If leaks are present, the wheel cylinder or caliper needs to be replaced.
4. Brake Lines and Hoses:
* Issue: Clogged or restricted brake lines or hoses can prevent proper fluid flow, leading to brakes that don't release completely.
* Troubleshooting: Inspect brake lines and hoses carefully for kinks, rust, or damage. If any are found, they should be replaced.
5. Master Cylinder:
* Issue: Although less likely, a problem with the master cylinder (the main brake fluid reservoir) can cause issues with brake release.
* Troubleshooting: This is a more complex issue and likely requires professional diagnosis. Look for brake fluid leaks around the master cylinder.
Safety Precautions:
* Always use jack stands when working under a vehicle. Never rely solely on a jack.
* Wear safety glasses to protect your eyes from debris.
* Work in a well-ventilated area when using brake cleaner.
* Use the proper tools and techniques when working on your brakes. If you are uncomfortable performing brake repairs, it is best to take your truck to a qualified mechanic.
Before you begin any repairs, consult a repair manual specific to your 1990 Ford Ranger. This will provide detailed instructions and diagrams for your particular vehicle. Improper brake repair can be dangerous. If you're not confident in your abilities, it's always best to consult a professional mechanic.
