Turn Signal / Light Problems

JMFM

MEMBER
2002 MERCURY COUGAR
6 CYL
2WD
AUTOMATIC
131,000 MILES

When I turn my headlights on, the right turn signal illuminates on my dash and all of the turn signals on the right side outside of the car illuminate. They do not flash. Just stuck on. If I flip the turn signal switch for them to come on, nothing happens. The left side signals all work fine. If I turn the headlights off, the right side turn signals including on the dash go off. If I flip the right turn signal switch while the headlights are off, all of the turn signals flash and my license plate lights even flash as well. I have replaced the turn signal switch and relay and that did not fix it. All of my bulbs are good. I do not know what else to do. This just started happening and I cannot figure out what the problem is. Please help me if you have any idea what could be causing this. I would really appreciate it.

6 Replies

CARADIODOC

MECHANIC
33,752 POSTS

You have described perfectly the classic symptom of a bad ground. To verify it, turn the head lights off, turn the right signals on, and you will find the left rear signal is also flashing dimly. If you remove the left rear signal bulb, the right rear bulb will stop lighting up.

I have to qualify that last statement. The right bulb's current may still be finding a path to ground through the license lamp. Regardless, it's the ground wire for the right rear lamp assembly you need to look at. Some bulb sockets use a push-in ground terminal that is noted for corroding. There could be a wire that got cut from something rattling around in the rear. A splice could be corroded. If there's a trailer wiring harness and someone used Scotch-Lok connectors to splice the wires, those do not seal out moisture, and corroded wires are the most likely suspect.

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Sunday, November 20th, 2016 AT 2:42 PM

JMFM

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4 POSTS

We worked on it all day today trying to track it down. When we pulled the fuse on the right front corner running light, everything started working fine. In the manual it was just called the "right side lamp". Regardless, I just pulled the fuse on the left one as well and now it matches. Those lights aren't that important to me. The turn signals work so I am happy. I might look into it further later on, but I have spent too many hours on it here recently and I am just going to leave it alone. I appreciate your response and I apologize for the delay in my response. I have been working on it all day and I just came inside and saw this.
Thanks again!

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Sunday, November 20th, 2016 AT 4:30 PM

CARADIODOC

MECHANIC
33,752 POSTS

Before you get all "wrapped around the axle", a faster test is to measure the voltages on the offending socket, but to have validity, that must be done with the bulb installed in it. You should find 12 volts on one terminal when the tail lights are turned on, and pulsing 12 volts on a different terminal when the signals are on. One terminal must always have 0 volts, regardless of which lights are on or off. When there is a bad ground, you will find 12 volts or some voltage on every terminal. Typically there will be around 4 to 6 volts on the ground terminal. When you identify that one, use a jumper wire to ground that one and you will see the lights start to work properly.

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Sunday, November 20th, 2016 AT 4:57 PM

JMFM

MEMBER
4 POSTS

The fuses we pulled also effected the tail lights so they are back in and my problem still remains. We did find that the ground on one of the bulb sockets was broken off on my back up lights. We fixed it but the lights are still messing up. I am officially wrapped around the axle now. Lol. I do not know what to do. I will check the current on the bulbs like you recommended and I appreciate your help. This is very time consuming and aggravating!

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Monday, November 21st, 2016 AT 5:48 AM

JMFM

MEMBER
4 POSTS

The car is fixed! The problem ended up being a bad turn signal bulb on the passenger side year. When I switched out the 1157 bulb, everything was fine. Crazy! It lit up and everything but since it is a dual bulb, I guess 1/2 of it was bad. Thanks for your suggestions, time and help, I really appreciate it.