Turn Signal Issue

[mike_b_svt]

Hey Fellahs,

Ok, I've done some searching around here and other sites, but I'm not finding the right symptoms and the solutions I've tried have not worked.

Problem: Fast blinking turn signal for both left and right turns.
- Hazards and brake lights function normally. Head lights (high and low beam) function normally. Cruise Control functions normally (at least it did yesterday).

Over the last few days the fast blinking was intermittant and would only happen when I had the turn signal on (either direction) AND pressed the brake pedal.
Now it is happening at all times, just by turning the signal left or right.

I understand that the fast blink tells you that load in the system has changed, i.e. a blown bulb or bad connection. I checked ALL filaments in all bulbs front and back and they are all good. I thought it might be a corroded connector or bulb / socket, but that doesn't explain both sides suddenly flaking out.

I did remove the Flasher Module (little yellow box under dash, above the gas pedal). I even opened it up and inspected the contacts - they were ok, and I cleaned them up a bit. Still same issue.

So now I'm leaning toward the Multifunction Switch / Turn signal lever, but I tried wiggling it and whatnot, but the fast blinking doesn't change.

I don't think it would be a fuse, as all the lights work when they should.

Any other ideas or input?

Thanks fellahs,

 

[Crimson2v]

I would check the terminals on the back of the multi-function switch connector make sure none of the wires are pulled out.

 

[Jimmysidecarr]

Is it possible there is a bulb going out intermittently? Hanging filament which touches every now and then and lights up?

 

[mike_b_svt]

Is it possible there is a bulb going out intermittently? Hanging filament which touches every now and then and lights up?

Thats what I thought too, so I did a pretty thorough inspection of all the bulbs. Both filaments in each appear to be good.

Also, if it were a hanging filament I think it would only affect left or right, but not both. Maybe.

Pulling apart the stearing column now to check the multifunction switch.

 

[Ironhand]

Thats what I thought too, so I did a pretty thorough inspection of all the bulbs. Both filaments in each appear to be good.

Also, if it were a hanging filament I think it would only affect left or right, but not both. Maybe.

Pulling apart the stearing column now to check the multifunction switch.

I had a similar problem with a customers car. It wasnt a Mustang and the customer swore up and down it wasnt a bulb. I double checked the bulb and it "looked" to be ok. I replaced it anyways and it fixed the problem. Sometimes the bottom part of it does get alittle messed up but doesnt appear to be bad. Replace all 4 turn signal bulbs and go from there. If it still does it then it will probably be the multifunction switch but its hard to tell cause I cant test or see it in person.

 

[MaximumVelocity]

Fast flash also happens with LED bulbs if you don't use a resistor. If bulbs are OK (and the right part number (no 3156 / 3157 mix ups)), look for a short to ground (although this should pop a fuse first).

 

[330mach1]

wrong buld in there possibly?

 

[UncleSAm]

i had a similar problem with m 98, whenever i had it on a performance tune it would do that but if i dummed down the tune to less aggressive it would go away...could be a computer thing. and it happen after i was running the tune for quite some time

 

[mike_b_svt]

Thanks for the input fellahs. All the bulbs have been in there for... well, from the factory. You guys are probably right, and one (or more) is getting ready to fail.

Pulled apart the multi-switch last night and all the contacts looked ok. Some of the dielectric grease was a bit dirty, so I cleaned it up though. Put it back in and same problem.

Threw the battery on the charger last night, thinking maybe it was a bit low and causing issues.

Guess I'm gonna drive with it as is for now. All the lights work, so i'm not endangering myself or others - at least no more than normal >.>

Might pick up a new set of bulbs, and maybe a flasher relay to see if they fix it.

Thanks again, and I'll update if I find a solution.

 

[mike_b_svt]

Update:

Ok, so I charged up the battery (BatteryMinder) for about 36hours before it topped off. I checked the voltage before hand and it was at 12.3V. Battery itself is less than 1 year old.

Next morning my flashers were working almost normal. I would get a double-flash for the first blink when I first turned on the blinker, but then it would switch back to normal.
Drove home in the evening and it was acting flakey again. Some blinks normal speed, some fast.

So I checked the alternator output last night and it is putting out 14.1V at the battery terminals at idle, no accessory loads. Now, when I checked it last year before replacing the battery it was putting out 14.4V in the same conditions.

Now I'm wondering if my alternator (factory stock!) is starting to go out.

Anyone have any theories on this?

 

[mike_b_svt]

Alright, so it turned out that my alternator was dropping voltage as it heated up. After it was warm it was only putting out about 12.5v.

Got it checked and it had a bad diode, so I replaced it.
Think I'm gonna keep the original alt and just have it rebuilt ~ probably cheaper than buying another new one sometime down the road.

Turnsignals seem to be back to normal, but I admit I haven't had it out long enough to get it hot yet. Either way the alternator needed replaced.

/sigh... I've joined the new battery and new alternator club. Only got about 35k miles out of them, but I guess 8 years isn't too bad

 

[mu22stang]

Alright, so it turned out that my alternator was dropping voltage as it heated up. After it was warm it was only putting out about 12.5v.

Got it checked and it had a bad diode, so I replaced it.
Think I'm gonna keep the original alt and just have it rebuilt ~ probably cheaper than buying another new one sometime down the road.

Turnsignals seem to be back to normal, but I admit I haven't had it out long enough to get it hot yet. Either way the alternator needed replaced.

/sigh... I've joined the new battery and new alternator club. Only got about 35k miles out of them, but I guess 8 years isn't too bad

The reduction in voltage output as the engine bay temperature rises is typical. My original (as far as I know, 2nd owner) alternator died at 45,XXX miles. I'm on alternator number 4. You get pretty good at replacing them after a while.

Did you ever replace the bulbs? Inpection vs replacement on a such a cheap part is a bit strange. You may have a great deal of knowledge on bulbs and be able to determine if it's faulty just by looking at them. But, why not just spend a few dollars and eliminate it as a potential source of the problem?

 

[mike_b_svt]

The reduction in voltage output as the engine bay temperature rises is typical. My original (as far as I know, 2nd owner) alternator died at 45,XXX miles. I'm on alternator number 4. You get pretty good at replacing them after a while.

Did you ever replace the bulbs? Inpection vs replacement on a such a cheap part is a bit strange. You may have a great deal of knowledge on bulbs and be able to determine if it's faulty just by looking at them. But, why not just spend a few dollars and eliminate it as a potential source of the problem?

I had more faith in the bulbs than I did with the Alt. Especially after checking them, and with all the "failed alternator" stories I've read on here.

I would have replaced bulbs if the blinker had been fast on one side or the other. But it started flashing fast on BOTH sides. What are the odds of bulbs on both sides failing at the same time with "hanging filaments"? Yeah, I'm gonna get a lotto ticket when that happens

Besides that, the car has felt "weak" lately and had a bit of intermittant stumble at 3k RPM. So that was another thing that pointed me toward the Alt instead of bulbs.