Forum > Classic Mustang Technical forum

Wiring Harness on a '66

(1/5) > >>

When I purchased my '66 Mustang, I was well aware that I didn't have a left turn signal (hence the big ugly 'Rejection' sticker on the windshield) because of something in the wiring harness.  I thought it would be a quick fix.  However, the person who owned it prior to me toyed with the wires and apparently wired them backwards (according to a friend of mine)

He took a look at the wires and spliced them.  After he spliced them, we tested the lights.  I still don't have a turn signal.  The parking lights work fine.  But when I turn the headlights on they over ride the parking lights.  I don't know what else could be wrong with it.  He said something may be wrong with ground wire or alternator.  I'm not sure, since I don't mess much with wiring in a car.  

Any ideas on what might be wrong with it?

The only way to find out what's wrong is to test the wires with a multimeter. Check the power wire at the light bulb with one end of the meter on the wire the other one in a non painted location of the body like a bolt. If you get 12 V on this wire then you have a ground problem. If not you can locate the appropriate  
fuse in the fuse box and test both ends to see if you have any power. If you do the problem comes from the wire runing from the fuse box to the signal light.
Someone may have a better idea to fix this problem but this is the way I would do it. Good luck and let us know if you get it to work.

I borrowed a multimeter and my buddy and tried out what you suggested.  The ground wires are fine.  I'm glad you suggested that so I didn't have to replace a perfectly good harness.  We've narrowed it down to one thing:  the turn signal switch.

It has to be.  You see, the boy I bought her off of replaced the steering wheel.  Of course, the steering wheel he bought was different, so a completely new steering column had to be used (it's not made for a '66 Mustang).  We think that he may have unhooked something or fouled something up in the process of changing it and the problem didn't show up until later.  That's the only other thing we can think of that could possibly keep the turn signal from working.  I'm more than likely going to have to take her somewhere to get this figured out.  Know of anything else that may be the cause?   :-(

The switch might be the right place to look at especially if as you say the steering wheel and column are not original but it can also come from the relay. I am not sure how they work but they should not be very expensive and you may replace it to see if it makes any diference or you can take your steering wheel and switch apart to check if you have any power on the wire connected to the switch and coming from the battery (meter connected on the wire and the ground on the body). If there is power the problem is between the switch and the signal light. If not it is between the switch and the battery.

Well...after what seemed like forever, we finally figured out what was wrong with it.  

The signal light wires were fried.  Boy, do I feel dumb.  I met a boy that helps his stepfather restore hot rods, and he had a multimeter (I think) different from what Eric had.  Aaron told me the problem was the wires in the signal light itself.  We replaced it and presto...turn signal.

She passed inspection.  However, when I press the brakes, the parking light comes on on the left side.  It never ends, does it?  I think that this has something to do with the harness this time.  I'm pretty sure Aaron installed the light correctly.  She's driveable and I just ride with my lights on so there isn't a question mark to oncoming traffic when I brake.  I would like to get this fixed in the near future.  Any suggestions on this one?  Should I go ahead and replace the harness, which, by the way, has been cut and spliced and taped in so many different places?  Apparently whoever did the wiring on her during restoration didn't know what they were doing.


[0] Message Index

[#] Next page

Go to full version