Owner's Problem Description
The owner reported that during hard braking to avoid a collision, the low traction light illuminated along with the brake light on the dashboard. While the low traction light turned off after a few seconds, the brake light remained illuminated. The owner checked the brake fluid reservoir, which was confirmed to be full. They are looking for guidance on diagnosing the brake light issue further.
Professional Technical Analysis
The 1993 Chevy Camaro exhibits a common issue where the brake light remains illuminated after hard braking, accompanied by activation of the low traction light. This scenario could indicate a malfunction in the brake system or a possible issue with the ABS module. The braking system on this vehicle is equipped with a hydraulic control unit (HCU) that manages brake pressure and monitors fluid levels. A key component in this system is the brake pressure switch, which signals the dashboard light if it detects a loss of pressure. Given that the brake fluid reservoir is full, it’s unlikely that fluid level is the issue. The next step is to investigate the ABS control module, as it may have stored fault codes that can clarify the cause of the warning lights. It’s important to connect a compatible OBD-I scanner to diagnose the problem effectively. The ABS module should be checked for proper operation, and the brake pressure switch should be tested for continuity. The car's age and potential corrosion in wiring or connectors may contribute to intermittent faults. In summary, a systematic approach involving scanning for ABS trouble codes and testing the brake pressure switch is critical in pinpointing the issue, ensuring vehicle safety and functionality.
Possible Causes
Most common causes (ordered by frequency):
- Brake Pressure Switch Malfunction: The brake pressure switch is responsible for signaling the brake light on the dashboard. If this switch fails or has a poor connection, it may incorrectly activate the brake light, even when braking is sufficient. Testing the switch for continuity with a multimeter is essential; it should show continuity when the brake pedal is pressed. If not, replacement may be necessary. Typical part number is GM P/N 18001462, costing approximately $30-$50. - Brake light remains on despite good brake pedal feel, continuity testing shows switch failure.
- ABS Control Module Failure: The ABS module may have internal faults or stored codes due to previous issues with the braking system. This can lead to false signals being sent to the dashboard lights. A proper diagnostic scanner is required to retrieve any fault codes from the ABS system. A common failure in these modules is the electrical connector corrosion, which should be inspected. Replacement parts typically range from $200-$400. - ABS warning light may also be activated, stored codes indicate module fault, visual inspection shows corrosion.
- Wiring Issues: Damaged or corroded wiring in the brake system can cause intermittent connections, leading to malfunctioning brake lights. Inspect all related wiring for signs of wear, corrosion, or loose connections. Use a multimeter to check for proper voltage at the brake light circuit. Voltage should be present when the brake pedal is pressed. Repair or replace damaged wiring as necessary. - Intermittent brake light function, visual inspection shows frayed harness or corrosion.
Diagnostic Steps
Professional Diagnosis Process
Follow these systematic steps to accurately diagnose the issue. Each step builds on the previous one to ensure accurate diagnosis.
- STEP 1 - Initial Visual Inspection: Begin with a thorough visual inspection of the brake fluid reservoir, brake light bulbs, and wiring connections. Look for any signs of leaks, corrosion, or damaged wires. This step is crucial to rule out obvious issues before deeper diagnostics.
- STEP 2 - Brake Pressure Switch Testing: Remove the brake pressure switch connector and use a multimeter to test for continuity. With the brake pedal pressed, there should be continuity. If continuity is not present, replace the switch with OEM part GM P/N 18001462.
- STEP 3 - ABS Module Scan: Connect a professional-grade OBD-I scanner to retrieve any stored codes from the ABS module. If no codes can be retrieved, inspect the ABS module connector for corrosion or damage. This may require a specialized scanner capable of accessing older OBD-I systems.
- STEP 4 - Wiring Inspection: Inspect the wiring harness related to the brake system for any signs of wear or damage. Use a multimeter to check for proper voltage along the brake light circuit when the brake pedal is pressed. Repair or replace any compromised wiring as necessary.
