Where is flasher loction on 1990 gmc serria and what does it look like

You have one flasher for your turn signals and one for your emergency flashers. If one turn signal works then it isn't your flasher. I would look at the connector under the bed where the trailer plug splits off. This is a common place for corrosion. With a 12v test light you can probe from the light for power. If there isn't anything at the connector at the light move up to the splitter. If you have a signal there your problem is between it and the tail light.

Normally, yes.The flasher should be in the fusebox - turn on the signal and get your ear close to the fusebox - you should hear the flasher clicking. There should be 2 flashers there - 1 for the turn sigs and the other for the hazard/emergency flashers.

its most likley a bad bulb or actually a connection.. couple things.. check bulb connection n check ground wires... if that dont work replace flasher..

This problem could be a fuse, flasher or signal light switch, the most common is a fuse or flasher, i would first check the fuses and is they are good then replace the flasher.

If you turn sigals one or both dont work this could be a flasher ,,,change flasher not expensive.

If they don't blink, the round flasher underneath the driver's side kick plate could be the culprit, There is one for the hazard flashers and one for the turn signals.

Also, check for bulbs burnt out.

I had the same problem and the flasher is not located in the fuse box because it is not a normal flasher. the cougar has an electronic flasher unit that is located on the left side of the center console. the best and cheapest place to order a new one is amazon.com. they run about $30-$40

if i remember right the flasher is located on the back side of the fuse panel

it is inside, under dash, on left side is a plastic sound protector, mine had 3 screws holding it up, drop this down and straight in you will see a 1" round thing - this is the flasher, pull it out and replace with new one (there are two flat prongs that plug in). It appears this is a well guarded secret!