1 Line On The Speedo
One single horizontal bar on the speedo display means you have a CAN bus fault, this can either be really easy or really hard to fix.
The CAN (Control Area Network) bus is a simple connection that runs between all the
major electronics in the car, it consists of a CAN high and a CAN low wire. It allows
all the electronics to talk to each other so they know what each thing is doing.
Failure Speedo Symbol
If there is a break in a wire, a connector is loose or power is lost to a part of the electronics,
you will see this symbol flashing on the speedo where the gear number is normally shown.
Fixing The Fault
More often than not it is as simple as a blown fuse. This blown fuse cuts power to an item so it
fails to communicate on the CAN bus and therefore causing the error. Usually it is either:
If replacement fuses blow as soon as you turn the key then you will have to investigate the wiring
or the controller it is attached to. Fit a new fuse, unplug the controller attached to that fuse and
try again. If the fuse blows then you probably have a chaffed wire touching an earth point.
If the fuse stays intact then the fault will probably lay with the controller.
Check ALL the fuses to ensure they are all intact. If that doesn't work, I would suggest
turning the car off and checking 2 connections.The first is to the ECU which is on the
side of the airbox, the second is on the rear of the speedo (circled green).
And If That Fails?
Now things get complicated. Wires rarely become damaged inside a car as they are bundled
together and don't move and therefore don't rub. This, however is a rare fault on the Roadster.
Think back to what modification you did just prior to the CAN bus fault and look in that area.
Check the connectors are seated properly in the:
The ESP controller has been known in some cars to allow water penetration
onto the connections which over time rusts the pins and causes problems.
Check all your earthing connections around the car.
Use a multimeter to check the CAN bus wires to ensure there are no breaks.
As a last resort, go to smart or a company with Win-Star computer to see if the
on board diagnostics give a clearer explanation as to why the problem has occured.