ABS Trouble Guide
Checklist to route out the problem
by Lotus Cars Ltd
The fact that the ABS light is on constantly identifies a malfunction on the ABS system and there will be no ABS operation. The Brakes will operate correctly but without the ABS feature.
If the light is constantly on there should be a Code stored in the self diagnostic memory which can be interrogated by the Lotus Dealer and the source of the problem identified.
If this test cannot be carried out there is detailed system checking procedure in the Service Notes.
The Items to check are :-
Wheel Speed Sensors - are all 4 sensors giving a signal? Ensure the sensor tip is clean and has the correct gap with the pole wheel.
Pump - Does the ABS pump run when the ignition is switched on. It should run for a few seconds to charge the system on start up (ignition on). It can be depressurised by pumping the pedal 40 times with ignition off before checking this. The pump should stop when the system is charged.
The pump operation is then controlled by the pressure switch. Once the pressure falls as the brakes are used the pressure switch senses the drop and restarts the pump which will run again for a few seconds. This switch could be defective if the pump is not activated. There is also a relay in the system (on the bulkhead) that could be defective and stop the pump activating.
The Accumulator could have lost its charge - there is also a test procedure in the Service Notes for checking this.
Another possible problem is the brake light switch on the pedal box. This needs to be checked to see if it is working and adjusted properly.