VT Calais goes to stall when braking........

Hey everyone, how are ya's?

I just recently purchased a 1998 VT Calais 5L and tonight when i was driving around i had the heater cranked right up on 30 degrees and i went to turn right into a street and as i hit the brakes and turned the headlights and dash lights dimmed right out for a second and all my dash lights (reds) lit up kinda like it was going to stall or something, so i kept driving and trying different things, i put the temperature down to 17 degrees and all the lights still dimmed a bit but not as much and the reds didnt come on, so then i turned the climate control off and it didnt happen at all. Has anyone else ever had anything like this or does anyone have any ideas as to why this might be happening?

Cheers

 

No worries, ill look into it, thank you

 

I did a error code check today and it came up with 36 - vacuum leak so ill find out where it is and get it fixed, thanks for the help m1lky