Turn signal flashes fast on one side only


Asked by Jan 11, 2014 at 07:29 PM about the Mercury Grand Marquis

Question type: Maintenance & Repair

4 Answers


We checked bulbs and even replaced them, but still doing the same thing.

32 out of 32 people think this is helpful.

Are both front and rear flashing fast on that side?

21 out of 21 people think this is helpful.

Hi, you didn't mention what year the M.G.M was so I can only give you general information. When asking a question always give as much info as possible about the vehicle in question like make, model, year, etc. anything that pertains to the problem. All the bulbs are basically on one main circuit line but pair off to each as is the flasher that controls them. If one bulb is burned out or corroded or just bad, the flasher will still open and close but now faster because of less resistance on that side. . Recheck ALL the bulbs even on the opposite side of the car too. If it's flashing fast on the passenger side, you got a burned out bulb or a bad connection somewhere but not necessarily on that particular side of the car and vise-virsa. Check both sides as that flasher under the dash controls the turn signals on both sides of the car. Does the car have cornering lights? That's a big white light on the front fenders that comes on and stays on while the turn signal is on as you go around the corner thus the name.. If that's burned out there's your problem. It's usually down low but again I don't know where exactly on your Grand Marquis as you didn't give the year of the car and different years are different locations. . Also check those little bulbs in the parking lights. My Crown Victoria (virtually the same as a Grand Marquis) has numerous little bulbs on the front corners of the car and you just might be missing checking them all. Sometimes you didn't even know one was there. They don't all flash but are on the same main circuit. Best to check for a burned out bulb at night in your driveway or inside the garage where it's real dark. You might notice something you overlooked in the daylight. Turn on your 4-way flasher to check all the bulbs at the same time. Wiggle bulbs and check for corrosion with each by pulling bulb and reinstalling then wiggling them to see if there's a change in brightness that you wouldn't see or notice during the day. If all the bulbs light up and are good then it's got to be a bad ground somewhere and unfortunately that could take a long time to find but again, just recheck all your bulbs and their connections. It might take awhile but you will find it eventually. After cleaning and checking all the connections, spray some dielectric compound (comes in a spray can at the autoparts store) into all the sockets and connections. This stuff stops corrosion from starting and stops it from coming back too. .Sorry I couldn't be more help.. Good Luck, Kenny/MrBlueOval

7 out of 7 people think this is helpful.

I don't need many details :-) That is a common problem. I had two 2000 Grand Marquis, and they both had this problem. There is a 'bug' in the electronic light control module. You need to find a replacement box, and this will cure the pain. Worked for me - both times...

4 out of 4 people think this is helpful.

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