'02 S60, A warning stays on

Did you get a genuine Volvo part? has to be genuine..

check for codes is the SRS system it should show a code that will have to be checked out.

indicates a problem ground or loose battery terminals where the ECM looses contact and control
could be a problem ECM
run the fault codes

U have a bad relay for your cars computer it under the hood on the drivers side

You really need to see the dealer about this, your SRS system is not turned on until this problem is diagnosed and corrected, NO AIRBAG RESTRAINT SYSTEM.

you say you did the transmision service 2 days before this started. im assuming you took it some were to have that done. if so take it back something did not get put back together right nto enough fluid or way over full .something is not right more than an alert message to a periodical maintance . and yes some times there are clitches to be recleared and reset that have to be done by the dealership

No! This electrical! I'm having the same problem with my 04R too. I've replaced the alternator and battery. Still having the problem. Dealer says there is module thats going bad and draining my electrical system.........

So many lame responses...I went through this same experience and can tell you in my case it was the alternator. All of the warning lights such as the ABS light, airbag light, the warning about the brakes are all because the alternator is not providing the DC voltage all of the car's sophisticated electronics need to correctly monitor these subsystems' status. Mine left me high and dry by the side of Interstate 5 needing a tow. The low battery warning was off and on for about an hour before all of the other warning lights came on, and then about 5 minutes later every needle on the dash went to zero and the car died. After sitting waiting for the tow, it did start up again, but we got it towed to a dealer (thank god it got us within 8 miles of a dealer! the first warnings started when we were in the sticks) who diagnosed it as an alternator. $1200 and two days later and all is well again.

You need an EOBD reader. Your fault is probably in the module (located in the console) (it's bolted to the hump). The code reader will specify the fault.

you will have to have the SRS system reset at volvo dealer. should be around $85 for reset