There is disturbing evidence to suggest that some drivers aren’t aware of the role and critical importance of the ABS ISO7638 line for articulated trailers whilst in transit or, more worryingly, are deliberately leaving it disconnected.
The use of the ABS ISO7638 line (otherwise known as the EBS/ABS line) became law in May 2002 where the tractor and trailer are both provided with connections.
The EBS/ABS ‘Suzie’ connection provides electrical and data feeds to the trailer’s ECU or ‘brain’. The ECU then controls the anti-lock braking system (ABS), load sensing (LSV), roll stability (RSS) and suspension control which regulates the correct trailer ride height and, in turn, the overall trailer height.
So why then might a driver leave it disconnected? There are, surprisingly, a couple of reasons. Firstly, the roll stability system (RSS) automatically applies the brakes if the trailer is going too fast round a bend. This has an impact on both speed and fuel economy and, if a driver is either in a rush or targeted against fuel consumption, they might be tempted to disable this ‘inconvenient’ feature.
The other apathetically induced reason is that it just “doesn’t seem to do anything”. Indeed, when the driver pulls away, his/her brakes and lights will appear to work. What the driver may not understand is that they are more likely to experience jack-knifing, aquaplaning, brake lock, rollover, bridge strike and, more commonly, the fact that the 44T rig just won’t be able to stop as quickly when trying to avoid that pram that’s just peeked out from a line of parked cars.
So, just in case there is any lingering doubt, failure to connect the ABS ISO7638 line correctly results in the risk of catastrophic, life-threatening accidents. If the driver fails to use the line/ ‘Suzie’ correctly and there is a collision in which someone is killed, then the driver can face a charge of manslaughter.
Further information is available from the DVSA at https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/243981/undertanding-your-braking-connections-is-vital.pdf