Car MOT Manual 2012 onwards
3.4 Anti-Lock Braking and Electronic Stability Control Systems
InformationThis inspection applies to all systems whether original equipment, optional or after-market.
Electronic Stability Control Systems are commonly referred to as ESC, but may also be known as ESP or some other acronym. The dashboard warning lamp for these systems may take various forms and a vehicle should only be failed when the tester is certain that an illuminated lamp indicates an ESC malfunction. This may require reference to the owners handbook if one is available.
When testing vehicles that have ABS fitted the road wheels should not be allowed to rotate clear of the standing surface with the ignition on as this can cause the ABS system to indicate a fault which may require specialist equipment to rectify.
If an ABS or ESC system has been intentionally rendered inoperative, the whole system must be removed. However, this does not apply to sensor rings or other ABS components which are an integral part of another component e.g. brake disc or drive shaft.
Method of Inspection1. If the vehicle is fitted with an ABS and/or ESC system, check that the relevant warning lamps:
a. is fitted
c. does not indicate a fault
d. in the case of ABS only, follows the correct sequence of operation.
Note: The sequence varies with the type of system. Refer to VSI, manufacturers or other reliable data, e.g. purpose produced charts, books, etc.
2. Check the presence and condition of all visible ABS and ESC system components.
3. Check the condition of all visible ABS and ESC system wiring.
4. Check all ABS and ESC system components for any inappropriate repair or modification.
5. Check the condition and operation of the switch if fitted to turn the ESC system on and off.
Reason for Rejection1. A warning lamp:
a. is missing
b. does not illuminate
c. indicates a fault
d. for ABS does not follow the correct sequence of operation.
2. An ABS or ESC system component obviously missing or excessively damaged.
3. ABS or ESC system wiring excessively damaged.
4. An ABS or ESC system component inappropriately repaired or modified.
5. An ESC system switch insecure or faulty.