I know electrical problems are common, and now my my 66 coupe seems to have developed one (or more). Specifically, the front and rear right turn signalsand dash indicator light do not flash when the headlights are on. They just stay lit. However, if the headlights are off, theright turn signals and dash indicator flash asthey should. I also notice that when the right turn signal is activated, with the headlights off, the rear left turn signal flashes as well but is very faint.

Any ideas on where to start to diagnosethe problem? I have no electrical experience to speak of so any and allhelp would be appreciated.

Lee

 

Electrical problems definitely suck. At least you are able to reproduce the problem for trouble shooting purposes. Clearly there is a shorting issue. Start with a schematic and a long wire to temporarily substitute the wire you are testing for a short. This may be easier said than done if previous owners have already started chopping the electrical system (possibly the reason you're having problems). Once you locate the problem wire, you have a choice of finding where the problem lies, or simply abandoning the problem wire in place of a replacement.

Any chance your mustang has replacement guages (i.e. accessory type tach/battery/temp)? That's how mine got screwed up.

Good luck.

 

A few of the gauges have been replaced as I have a box with the old temp and amp gauge in it. I'm half-inclined to take it to a shop because I have no idea where to begin.What basic tool or tools do I need to check for a short and how is it done? Thanks for the input.

 

The best and cheepest tool is a lighted tester you would get from a automotive store. It has a light in it and when you put it across your bat it lights up. Start by connecting the alligator clip to the pos (+) side of the bat and put the point of the tester on the bezel of your turn signal lights, if you have good grounds then the light should go on.......Then we can go from there.

 

Try using this... Don't know if the wire colors changed.... There are links in the FAQ for wiring schematics for a 66.

 

Before tearing into everything, try swapping the flasher unit first and see if that doesn't fix things. It has been years, but I thought that sometimes a light would become solid when the flasher took a dump.

If that doesn't work then have at it with the wiring diagram. [sm=signs003.gif]

 

Yeah, I at first I thought it may be even a burned out bulb. However, it seems to only be affect his turn signals when the headlights are on.

Another piece of advice is to take your time and take notes as to which lines you've already tested for. I've been known to get confused and test the same lines multiple times (and not on purpose!).

 

I would check your Alternator voltage. When you pull the lights on you may be drawing the voltage down enough the flasher won't cycle. Check it at the battery lights off then pull the lights on and recheck. If drops below12.5 volts that may be your problem.

 

Thanks for all of the replies. I will go to the local Napa store to get the flasher and replace it this weekend. Sorry for being so dense, but if I need to test a wire for a short, for example, one of the wires coming out of the taillight socket, how exactly do I test it?

Also, does the wire loom for the taillights run underneath the door sill plate on the driver's side. If so, I have removed the plate numerous times to deal with the kick panel and quarter trim panel. Maybe I drove a screw into one of the wires and caused a short. The reason I say this is that I have had the car for a year, it is in great condition, and the turn signals all worked normally when I bought the car. Thoughts?

 

Take a long piece of wire, say 10 feet or so, and solder two aligator clips on each end. Take one and clip it to the load side of the flasher (not the hot/power supplyside). Run the wire around the outside of the car, open your trunk and clip the other aligator clip to the tail light connector (this part does not have to look pretty). Turn on your turn signal and your head lights and test for a blink. If you've isolated your problem, then get creative about running a permanent line. If you've got endless time, you can try to determine where the break is.

Its possible you may have knicked a cable with a screw, but I'm now thinking that 67Coupe may be onto something... Check your Voltage first. Go ahead and turn on the fan blower, too, to really load the electrical system while your testing.