It's probably the switch.
Its on the door panel next to the door handle. at least that's where it is on my 1992 190e 2.3
The motors are underneath the seats
On my 1984 190E, it is simple - there are a couple of tabs at the bottom of the back seat (where your heels would be if you were sittng), you have to look, the seat will pull right out!
You have to remove the entire door panel. Some models are screwed on and some models just snap on. For the very best advise, take it to you closes Mercedes-Benz dealer. Good luck!
I have a 1987 Mercedes that has no trunk key. Do I remove the back seat to get in?
How do you remove the seat to replace the battery on the mercedes r350 2006
The 1990 Mercedes-Benz 190E 1.8 did not come equipped with airbags as a standard feature. Airbags became more common in vehicles during the early 1990s, but the 190E model from that year typically relied on seat belts for occupant safety. Some later models or trims may have offered airbags, but it was not standard in the 1990 version.
No. All motors controled. Check your fues and the control switch.
battery is located under the rear seat
If the heater still works the bulb is just burn out. I doubt you can change the light you will have to replace the switch.
Check that the wire that controls the seat adjustment has not been cut through.