Function of individual components · 1. Conb"ol module (ABS 5.3 and ABS / TC 5.3) Note

911 Carrera (996) Anti-lock brake system diagnosis Function of individual components 1. Conb"ol module (ABS 5.3 and ABS / TC 5.3) Note This module processes incoming signals and The relays cannot be exchanged. actuates the solenoid valves or/and the return In the event of replacement, the complete pump in the hydraulic unit when wheel slip is hydraulic unit must be replaced. excessive (see also System description). If the ABS or ABSjTC switches off when a system fault is detected, it actuatesthe MIL and stores the fault in a non-volatilememory. 3. Fuses} 3a. A 50-A fuse in the current distributor Note (Fl / arrow) protects the return pump The control module and relay are not supplied and the solenoid valves. individually.}In the event of replacement, the The current distributor is located under the complete hydraulic unit must be replaced. instrument panel.} The fastening points are accessible from the luggage-compartment side. 2. Relay 3b. The 15-A fuse B 9 (fuse holder B / fuse The solenoid valve relay is actuated by the No.9) on the central electrical board control module (closes) as soon as the control protects the control module's electrical module receives voltage from the generator supply (ABS and ABS/TC). (D+/terminal 61). As soon as the relay has The arrow points to fuse holder B (field 2). closed (picked up), battery positive voltage (terminal 30) is present at the valve coils On vehicles with Traction Control (TC),the of all solenoid valves of the hydraulic unit. 15-Afuse B 1 (fuse holder B / fuse No.1) on the central electrical board protects the If the ABS or the TC (ABD)begins to control, supplyto the "TC OFF"rocker switch (switch the control module applies negative voltage for switching driving stability control on to the appropriate valve coil of the valve to and off). be controlled at the appropriate wheel. 4. Speed sensorsThe return pump relay is actuated (with a negative voltage) by the control module if The speed sensors provide wheel speed required, and closes. information(speed informationfor each wheel) As soon as the relay has closed / picked up, to the control module. These speed sensors battery positive voltage (terminal 30) is present operate according to the inductiveprinciple, at the return pump, which then runs. in which sinusoidalalternating voltages are generated in accordancewith the number of teeth on a pulse wheel and at a frequency that is a measure of the wheel speed. 45 02 Diagnosis/troubleshooting 45 -D 11