Dimming lights

[Banner Rav]

I've been doing a lot of night motorway driving in past month and on quiet, dark sections I've noticed the lights dim slightly for a brief second every now and then. It looks as if a load is coming on the Battery and wonder if it could be something like the cooling fan cutting in that's causing it. Wonder if anyone else has noticed this, the car is starting and driving perfectly so hopefully nothing to worry about.

 

Car is a 65 reg 2.0 diesel

[daveh_rav4]

65 reg ?  is that a 1965 registered 2.0 ltr. diesel?  Or is that some new fangled way of dating number plates?  Rav4's were not around in 1965.   If that is an old vehicle, it probably has a dynamo?  Please confirm the vehicle/age that you are refering too?

Sudden dimmimg of lights can be caused by several things... a bad connection, i.e. Battery terminals, a cell going bad in the Battery when extra load is applied, bad earth to the chassis somewhere; even a faulty light switch or wiring.  I would check as many connection points, including fuse holders etc.  Then have a load test done to the Battery... you need a high current discharge test to see if the battry is holding up.  Also have the dynamo/alternator checked for regulation and current output ; you may need an auto electrician to do these checks if you can't do this yourself or don't have the correct test equipment.  A fan cutting in should not take enough current to sink the battery or charging system unless it is faulty (put an ammeter in series to check the current draw).  

I remember years ago I had a total lights failure on a car when driving at night down a very dark winding lane... I had to pull up with just a memory of the last site of the road I had; most disconcerting and a wonder I did not end up hitting a tree or a ditch LOL

[bonjo]

I had the opposite a few years back; it was the regulator sending out too high volt to the bulbs.

With dimming you have additional suspenct as daveh mentioned. start looking out dirty bulb connection and dirty/ loose earth connection

[Heidfirst]

3 hours ago, daveh_rav4 said:

65 reg ?  is that a 1965 registered 2.0 ltr. diesel?  Or is that some new fangled way of dating number plates?  Rav4's were not around in 1965.   If that is an old vehicle, it probably has a dynamo?  Please confirm the vehicle/age that you are refering too?

it will be a 65 plate i.e. late 2015/early 2016 registration (xx65xxx).

[daveh_rav4]

Thanks Scott... my old school ways shows through again!  A 65 plate in my day meant it was a 1965 reg... simple eh!  Probably when the frigged around with the regisration dates it got screwed, d'oh!