What causes the ABS light to illuminate in a Peugeot 308?

[VonKeira]

There are several conditions under which the ABS light may illuminate, each with different causes and solutions: Condition 1: ABS warning light stays on constantly (most common). Cause 1: The ABS speed sensor's sensing area is covered by mud, sludge, or other contaminants, affecting its ability to detect speed signals. This prevents the ABS computer from determining vehicle speed or wheel slip rate, thus failing to issue appropriate braking commands. Solution: Clean the speed sensor and adjust the gap between the sensor and the signal ring to restore normal function. Cause 2: Loose system wiring connections or poor ABS relay contact causing signal issues. Solution: Check all wiring connections and secure any loose connections. Condition 2: ABS warning light illuminates intermittently, turning off during acceleration. Cause: Battery voltage drops below 10.5V when multiple electrical components are in use. The light turns off when engine speed increases and voltage rises. Possible low voltage supply to ABS system due to poor connections or grounding. Solution: Check battery condition, charging system, and power supply (including voltage relay and connections). Condition 3: ABS warning light stays on after engine start until engine is turned off. Cause: Poor grounding of ABS hydraulic valve body; faulty wiring connections; or ABS computer malfunction. Solution: Loosen and retighten valve body grounding screws, clean contact surfaces if necessary; check for enlarged connector gaps; replace ABS or ABS/ASR computer if needed. Condition 4: ABS warning light illuminates during high-speed driving. Cause: ABS computer detects significant speed difference between front and rear wheels; incorrect tire or wheel specifications. Solution: Verify correct tire and wheel specifications as indicated on the fuel filler cap label. Condition 5: ABS warning light flashes intermittently. Cause: Improper brake light switch adjustment; internal contact issues in brake lights. Solution: With engine running, press brake pedal and manually push switch lever down completely, then release pedal to reset position; replace brake light switch if necessary. When the ABS warning light is on, it's recommended to avoid driving as this indicates a malfunction in the anti-lock braking system. During emergency braking, locked wheels could cause loss of vehicle control, preventing proper deceleration or steering adjustment, creating significant safety risks.