Here's a breakdown of likely causes and troubleshooting steps:
Most Likely Culprits:
* Master Cylinder Failure: This is a top suspect. The master cylinder pushes brake fluid to the wheels. If it's failing internally, it might not be sending enough pressure to the rear brakes while simultaneously causing a brake light to stay on (due to a low fluid sensor or internal leak).
* Brake Light Switch: While less likely to cause a complete loss of rear brakes, a faulty brake light switch could be stuck in the "on" position, illuminating the brake lights even when the brake pedal isn't pressed. However, this is usually accompanied by a functioning brake system. A stuck switch is less likely to cause a total rear brake failure.
* Proportioning Valve: This valve regulates the brake pressure between the front and rear wheels. A malfunctioning proportioning valve could restrict or completely block fluid flow to the rear brakes.
* Rear Wheel Cylinders/Caliper Issues (Drum or Disc Brakes): Worn-out wheel cylinders (drum brakes) or calipers (disc brakes) can leak fluid, leading to no rear braking pressure and potentially triggering the brake light. A seized caliper could also cause the light to stay on. (This generation of Vandura could have either drum or disc rear brakes.)
* Low Brake Fluid: Check your brake fluid reservoir immediately. Critically low fluid suggests a leak somewhere in the system (master cylinder, wheel cylinders/calipers, lines, etc.).
Troubleshooting Steps (in order of safety and priority):
1. Check Brake Fluid Level: Locate the brake fluid reservoir (usually a clear or translucent container). Is it low? If so, you have a leak *somewhere* in the system and need professional help *immediately*. Do not drive the vehicle.
2. Inspect for Leaks: Carefully examine all brake lines, hoses, wheel cylinders/calipers, and the master cylinder for any signs of leaks (wet spots, dripping fluid).
3. Test Brake Pedal: With the engine off, pump the brake pedal several times. Does it feel firm and consistent, or soft and spongy? A soft pedal indicates low fluid pressure.
4. Brake Light Switch Check (Less Critical in this scenario): If you have basic electrical skills, you can test the brake light switch. However, given the complete rear brake failure, this is a secondary concern.
5. Professional Inspection: This is crucial. Do not attempt to repair this yourself unless you have significant automotive experience. A brake system failure is dangerous. Have a qualified mechanic diagnose the problem and perform the necessary repairs.
Safety Note: Driving with a brake light constantly illuminated and no rear brakes is extremely dangerous. Tow the vehicle to a repair shop, or call a roadside assistance service. Your safety and the safety of others is paramount.
