When the 451 fortwo started exhibiting the same problems when selecting
reverse, people immediately assumed that smart hadn't learned their lesson
and that a faulty brake light switch was to blame as with the previous models.
Although it can cause the fault, it is more likely to be the clutch or the software.
Explanation & Answer
by smart technician Ash
"This is a fairly common fault, it occurs more frequently on our sales display smarts as
they are left for long periods of time. Smart did at one point advise us to replace the
clutches for ones with a modified teflon spline. This does fix the issue but, on all the
smarts I have had the issue on, I have found a later software version for the gearbox
that gives it a higher threshold before it gives up trying to push the clutch in."
"In all the instances that I have had this issue, it has rectified it every time."
"It is something that would incur somewhere around half an
hour labour time for anybody who has run out of warranty."
When you stop, hold the foot brake and select reverse, if it just flashes an N at you
on the speedo LCD instead of selecting reverse, try this. Reselect 1st gear, drive
forwards a few inches and try selecting reverse again. So far I have had the problem
appear about 5 times and on each time, this quick method allows you to select reverse.
Anon found that edging forwards didn't circumvent this fault. However, they did find that manually
pushing the car back a few inches with their leg out the door seemed to allow selection of reverse.
Brake Light Switch
Florin V so far is the first and only 451 owner I have come across where the brake light switch has caused this fault although smart already seem to know about this fault and have issued a better sealed switch (although this sounds like the sort of nonsense that smart dealers make up as his local dealer hadn't managed to fix this fault before and had no clue how to fix it).