406 dimming lights

Can anyone tell me why my 406 2.2 HDI's lights dim for a fraction of a
second everytime I change gear, especially before the engine has fully
warmed up. I know of another 406 owner with the same problem, so i'm
guessing it's some sort of design foible.

Regards Phil.

 

Left field pure guess ... something with the reversing light switch?

 

I had similar on a 405 and I put it down to the drop in current from the
alternator as the revs dropped during the gear change. I also noticed that
revving the engine from tick over made them brighten and switching
headlights on while ticking over slowed the engine down.

 

on 405 diesels on warm up it was down to the post heat facility which kept
the heater plugs switched on until 65 deg c coolant temp
on a 406 hdi it shouldnt need them but it may be due to the heater booster
which consists of 3 heater plugs fitted into the cooling system which heat
up the coolant running into the heater to boost heater performance in cooler
climates
whats the temp where you are?

 

It's hitting around -1 to 4 centigrade around cambridgeshire this week so
guess you may have something there. Thanks for all your help guys. Phil.