Volvo Repair: 740 estate all brake light dont work. 88/89( model UK market, fuel pump relay, brake light switch

Question
All my brake lights have failed, with no warning indicator on the dash.I have replaced all the bulbs and checked the fuse-still no good.
Possibly it is the switch operated by the brake pedal but I am wondering if it is a relay(do they have one?) as the fuel pump relay was replaced recently when I broke down. I was only aware of the lack of brake lights when stopped by the police! so it could have happened any time since the fuel pump repair

Answer
it could be the relay or a brake light switch.it will need to be checked with a test light to see what the problem is.the relay is where the fuel pump relay is it is a large round red relay.I would check for power in and out of the switch then check the relay.