Hello. On my Volvo 240 DL the brake failure and parking brake light always come on when I start up the car but go away after I drive for about 20 seconds. The brakes feel fine. Theres plenty of pad left and the brake reservoir is full. Also there is not leaks what so every.
Idiot lights are supposed to come on briefly when you start up the car; that’s to indcate they are actually working! Yours appear to be staying on somewhta longer.
You are driving an aging Volvo, and if all is well, be very thankful. If I was in your shoes I would “let sleeping dogs lie”. It’s easy to spend several hundred dollars finding out that nothing is wrong with the car, it just needs new idiot lights. That will be a very exensive repair. Bear inmind that in the early sixties those same Volvos had almost none of these, just some mechanical gages.
I got rid of my '90 years ago, so I don’t recall how the lights were arranged. My book indicates that a '90 did not monitor brake fluid level. That started in '91. None of the 240s had pad wear indicators, so the light indicates either imbalance in the braking circuits or parking brake on, correct?
If you had said that it glowed until you press the brakes, I would suspect the circuit imbalance switch. Those do get old and corroded. Something that stays on for a length of time after starting is mysterious, but as noted, not necessarily anything to worry about.
You might play with the parking brake handle switch and its wire to try to get the behavior to change.
If someone retrofit on a later model master cylinder and tied the brake fluid level switch in to your light, perhaps that wiring is messed up?
A new brake balance warning switch for this car sells for about $50, if that turns out to be the problem and you really want it corrected.
If it were mine, I would continue to drive it as it is until the problem gets worse. Then it will be easier to diagnose.
I think its the alternator since today the dashboard lights flicker while the car was on.