This has been an annoying problem for a while but as it only happened occasionally, i just ignored it, turned the ignition off, started and off we went no problem.  But, idle hands etc so i took the cluster out and re-soldered the pins at the back of the pcb, refitted.....and now its worse!!!!! Strangely it seems to be setoff by putting the lights on (but only the dipped beam and not sidelights?) so i took out the interior lighting fuse thinking it might be a short on the backlight pcb supply and this definitely helped but didnt cure it completely.

First off, there was some terminals that looked to be joined up on the board but i just wanted to check what should and shouldnt be linked. The only diagram i have is the haynes, which is useless so does anybody have the pinouts for the connector so i can check?  Ive already spent an hour on google and still not found anything usefull.

Another thing though, when it does go (clocks die, instrument lights flashing and relays chattering etc) the engine still runs but it feels like i lose power steering.  This i dont understand.  Can anybody offer an explanation? as again, theres nothing in the haynes.

Cheers.

Sorry i have not had this issue but can only offer advice on your primary diagnosis based on my 35 years experience as an electronics engineer.

 

Think i would be checking alternator output / battery voltage first when this problem occurs.

I suggest that because as you say when switching lights on main beam, they draw quite a bit of current, which will cause a volt drop from the battery supply. The reason it isn't as bad on sidelights is due to not drawing as much current hence a lower line volt drop.

If you have resoldered the terminals, i would have cleaned them first, all the old residue / flux off first with a toothbrush and isopropyl (or pcb flux remover) to reveal the pcb artwork - that would show what is connected to what.

Time to remove the solder you have applied, clean the board and resolder.

In my vaux group this similar fault has occured and see that the power steering is electrical, when battery or alternator is knackered lads lose power steering !

Relays chattering in my eyes would be caused by either a bad earth or the 12v supply to relay coils fluctuating, but as some relays may not be switched on by default it sounds like you have a fluctuating supply or bad earth.

Very interested to hear if you resolve the issue.