Dash lights doesn't work when engine is on only work when engine is off

Hi guys

drove the car for the first time in the dark last night.

dash lights are lovely and bright when engine isn't running. Soon as I start the car they go out, only the clock display stays illuminated .

bit confused on this one

thanks Adam

 

so the clock is still lit up? odd one that! check the earths, theres one for the dash on the side of the head if its got an MFA cluster

No keys in ignition turn on the lights and the dash lights work

put key in and still work

soon as I turn the key and start the car the dash lights go out. I've checked all earths in the engine bay, behind fuse box - guessing it could be behind the clocks? I'm puzzled 

trace the grey wire from ignition switch pin P. it should go to the stalks, and nowhere else. if someone has spliced it to your headlight switch, thats why

Thanks john for replying again

could you explain a little more still trying to get used to the car? Eg where is pin p

sorry in advance

adam

 

take th eplastics off the bottom of the column, then unplug the connector from the rear of the ignition switch. Pin P is labelled

Hi john

took the plastics off. The solid grey wire goes from ignition but to the stalks - any other suggestions?

I'm really confused on this one it's likes it been reversed lol

adam

ok that's my easy idea out the window

do the sidelights work still with the ignition off? also do your plate lights still work when the dash lights go out? If not I suspect the light switch itself has failed somehow.

If the plate lights work ok next up get a bit of wire and stuff it in the back of the switch between the grey/green wire and the grey/blue pins. Since both the plate lights and dash light dimmer wheel are fed from the same feed inside the switch, if the above sorts the problem again its got to be the switch somehow, a random failure to be sure!

Hi jonny

sorry for the delay. I got a replacement switch as I had a donor car for a while, changed and still the same problem.

Dash lights only work when ignition isn't on.

cheers again

have you tried jumping the wire in the back

Yep - I've jumped the wire in the back of the switch and makes no difference still the same problem

any more suggestions? I'm wondering if it's the clocks?

Thanks again

adam

do the dash switches still light up when this happens or do they go out as well?

Yep - the lights light up everything else except the dash. I took the stereo out and checked everything - 12v on blue and white. Vdo gauges light up which come from cigarette lighter light which I've done. 

Sorry buddy about this problem

right can stop looking at the wiring as the switches all powered from the same feed!

going to be a clock pcb issue or maybe the earth to the head is bad if its an mfa cluster. its brown/white to the side of the head. also on some theres an extra braided earth from head to one of the coil mounting bolts that can help