Technical 49 www.aftermarketonline.net JUNE 2024 Sensory perception Frank Massey plots a steady course through the myriad of potentially misleading ‘fault signals’ to get a steering assist system back on track One of the challenges presented this month is quite common, however the symptoms and diagnostic data can be, in my opinion, misleading. Steering assist systems fitted to a wide range of VW/Audi/Seat/Skoda vehicles are fitted with a TWR module located at the rear of the NSF bumper. It is an electrically driven hydraulic pump that supplies a hydraulic steering rack with assistance. The system has evolved over the years so great care must be taken to ensure the correct pump is fitted. Two hydraulic lines, a high-pressure supply and low-pressure return follow the chassis rail then across the subframe to the steering rack. The early system variants housed the steering angle sensor within the rack input shaft. A cable from the potentiometer transfers rotational data to the right hand three-pin socket when viewed from the vehicle front. The left-hand socket has three of the four pins occupied, the left-hand two pins carry the high-speed drive can communication with data and diagnostics, the right-hand single wire carries a nominal battery voltage supply. Later variants like the one presented in my topic houses the steering angle sensor within the steering column. Therefore, the r/h module socket has a blanking plug preventing moisture ingress. The fuse panel mounted on the battery carries two system fuses, on the left a 25A fuse and a 40A pump fuse. The pump fuse is robust be careful fine cracks can be present reducing current flow to the pump. (see Fig.1 pump socket location / Fig.2 pump location) Our vehicle, a 1.4 seat Ibiza FR 2014, was presented with steering assist failure with failure warning lights illuminated. My initial investigation was a global vehicle serial scan, as this image shows the EPS 44 module is not present on the gateway module. Therefore no DTCs or data were Figure 1 Figure 2
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