66 thundrchikn tail light brake light nightmare!

[zx28]

I have a 66 bird 74000 miles. main problems are electrical. I have bought the cougars unlimited all in one relay. The relay i thought fixed all the tail light issues; however after holding the brake pedal for a min or so the relay will start buzzing and lights go off, shortly after releasing the brake and depressing again they come back on. The blinkers now seem to work flawlessly; and i have no running/tail lights at any time. can anyone shed some light on my situation. Thank you very much in advance for your time.

[simplyconnected]

Welcome to Squarebirds, zx28.

I am not familiar with the schematics for the Cougar setup, but I know this: Check your grounds. The relay coil needs a SOLID ground, or the reduced voltage will cause your relay coil to weaken and 'buzz'.

Everyone knows that +12 is essential, but two wires are required for all circuits to function. That means the ground side is equally as important.

I always run two #6AWG stranded copper wires from my battery to my trunk. The ground wire can be clamped to the floor or tapped-off along the way (for dash, seats, fuel tank...), but it is UN-broken all the way to the tail light housings. Depending on 20 feet of spot welded rusty steel is bad news in a 50 yr-old car. #6 copper wire is heavy, but not if you put a battery back there sometime in the future. Even if you don't, it's handy to have a power wire for inverters, relays, stereo accessories, etc.

Hope this helps. - Dave

[simplyconnected]

...The blinkers now seem to work flawlessly; and i have no running/tail lights at any time...

Running & Tail Lights, are separate circuits from your Stop Lights & Flashers. Electrically, they have nothing to do with each other. Use a 12-Volt test light to troubleshoot the circuit.

You have connectors in your trunk for all your lights. Turn your parking lights on, check for power on the Black Parking/Tail Light wire in the trunk. That wire originates at your headlight switch, so if you find power at the switch, and not at the lights, one of your connectors may be corroded or a wire is broken.

Of course, if you find +12 in the trunk, you may have bad bulbs or sockets. That is common.

[zx28]

simplyconnected Thank you sir for your help. I did not realize the two were on different circuits; ha that would explain my confusion. i believe my switch/or dimmer switch is the problem, my headlights flicker constantly and i can hear the switch making a ticking noise...probably not good. there is no power to the two prong plug behind the lights. i ll take the switch out tomorrow and see what i find.

Im sorry if i seem dumb for this question but i am 21 and this is my first classic bird...had a 94 sc t bird.... but you mentioned a relay coil in your post.. what or where i guess is that? If it is on the old rubber pad with all the crazy relays i may be able to figure that out but just curious. Thanks again sir for your time and patience

[YellowRose]

66 thundrchikn tail light brake light nightmare!

Hi Eric, recently, Dave ~ simplyconnected, put all our electrical wiring diagrams in one location in our Technical Resource Library. If you need all the '66 wiring diagrams, you will find them here.. They will help you, if you do not have a '66 shop manual yet. If you do not, you should invest in one. It will be a big help to you. As for your questions, they are not dumb... You were in need of good information, so please do not feel that any questions you need answers to are dumb questions. Not at all... Hopefully, these wiring schematics will help you trace out your problem. It sounds like you are on the right track with checking out that dimmer switch. It might be a faulty ground. Dave will tell you that many electrical problems can be traced back to a bad ground. If that is the case, do a good cleaning of the area the ground wire is attached to and that should end that problem. Unless the dimmer switch itself is bad, and that could also be the case. Let us know how you come out. Here is the link you need to get the '66 wiring schematics.
-Wiring

*new!* all TBird wiring diagrams in one location!

http://squarebirds.org/Diagrams-Sche...rams/index.htm

[simplyconnected]

Eric, there's no need to thank me because I'm only passing on information that the REAL designers passed-on to me years ago. We all start out equally ignorant until questions are correctly answered. Feel free to ask any question, here. We have a lot of great restorers who love to help out.

You really need a Shop Manual for your car, and an electrical diagram before you start.

From your description, I would start at the headlight switch. They are known to fail, especially if someone went nuts with trailer lights and/or high-intensity headlights.

Disconnect your battery before going under the dash. There is a button on your headlight switch that will allow you to pull the headlight switch knob all the way out. Then you can dismount the switch from the front of the dash. Look for signs of melted plastic, cooked wires, or loose connections. Take LOTS of clear pictures along the way. Sometimes a 6" mirror helps, and provide lots of light (I use those twisted fluorescent bulbs that don't get hot, in my trouble light).

Back in the day, we only had low-wattage headlights and the turn signal circuit was designed for slightly more capacity than the car came with. But, we can still use the original components to safely turn on MUCH more using relays.

A relay uses a simple coil that makes magnetism. When +12 is applied to the coil, magnetism pulls-in heavy contacts which completes a circuit (like a switch). So, a very small current energizes the relay which allows heavy current to flow through the contacts. A relay is an electrical switch, run by magnetism.

A great use for relays is modern, high-current headlights. All modern cars use this method: Close to the headlights, battery power is connected to one side of the 'headlight relay' contacts, and the other side of the contacts goes to the bulb wires. The relay coil is energized by the headlight switch on one side, and the other side of the coil is connected to chassis (GND). So, the real heavy current never goes through the headlight switch, it goes through the contacts which is controlled by the coil.

You can do the same with trailer lights: In the trunk, wire three relay coils to ground. The other side of those coils go to:
tail lights wire,
RH stop/signal light wire,
LH stop/signal light wire.

You need a power wire from the battery (always on) to the trunk that connects to all three open relay contacts. The other side of those contacts go to the trailer plug (to run the trailer lights). Because none of the trailer power comes from your dashboard, the turn signal rate won't speed up and there's no danger of overloading your headlight, turn signal, or brake light switches. The car's light bulbs turn on the relay coils, which close contacts, that run the trailer lights.

I'm not familiar with the rubber pad, and the relay coil I mentioned was for the Cougar stop light setup. - Dave

[zx28]

thanks

Thank you so much guys! The advice and schematics are a huge help. I will definately try to find and good shop manual. I will try to keep you busy as im sure i ll have many more questions. Thanks guys

[YellowRose]

66 thundrchikn tail light brake light nightmare!

Hi Eric, shop manuals are available through any one of the many Tbird parts houses listed in the Advertisements Forum below this. They all have them. You can also find them on eBay, I am sure. Anyone working on one of these old birds needs to have the shop manual at their finger tips. There are also other manuals, like the Electrical Assembly, Body & Interior Trim Assembly, Thunderbird Restoration Guide, and Owners Manuals available from them.

[zx28]

update

Alrighty for a small update, i got the headlight switch out yesterday. It has been replaced once before i believe because it is a motorcraft switch and not original ford. I also found the old rheostat out of the switch in the glove box. None of the wires look burned or corroded they look good. Looking at the diagrams that Dave posted i figured out which wire powered most of the dash lights and i just jumped a hot wire across to it to see if the lights worked and they all came on so i reckon that means that the switch is bad; or at least the rheostat anyway. I ordered a new one for like 15$ and i gotta pick it up today.

Im not sure where i read it, but i read that the dimmer switch can cause the headlights to flicker too even if you have a brand new headlight switch. If my lights still flicker is there a way to test the dimmer switch. It does make the lights brighter and dimmer like it should, so what about it would cause the flickering problem? Would it just be a ground that needs cleaning, or the switch replaced?

Would a chilton manual or another manual like that at a parts store be sufficient or is there a better one i should look for?

[simplyconnected]

...i read that the dimmer switch can cause the headlights to flicker too...

Let's be sure we are talking about the same thing. The headlight dimmer switch is on the floor. The dash lights dimmer is the rheostat in the headlight switch. Headlights have no association with the rheostat circuit.

Your headlight switch feeds the floor-mounted dimmer switch with ONE wire. That switch toggles between two output wires (low beams, and high beams).

Flickering headlights are caused by a loose or corroded connection, anywhere in the circuit. Most likely, a connection will be bad. Wires rarely fault in the middle (except at hinge flex areas). It could be at the headlight switch, foot switch, or simply a bad ground at the headlights.

Check the circuit UNDER LOAD, meaning, with the headlights on. Use your test light to determine where the circuit is 'breaking'.

Buy a real Ford Shop Manual. Chilton's and Motor's are ok for generic problems, but you need a manual for your specific car. They are still available and at a reasonable cost. Check eBay for good 'used' book prices.

Try these suggestions. If you have more questions, ask away... - Dave

[zx28]

well i just typed a book in the quick reply thing a few minutes ago and i guess it logged me out and so im going to try to remember what i wrote

I put in the new headlight switch and i now have dash lights but they begin to flicker on and off after a few seconds. the headlights stay on but the flicker too.

O yes sir Dave i was talking about the dimmer in the floor, sorry i wasn t more clear about that.

I still have no taillights when the other lights are on. I've been going over the diagrams and it looks like the tails run through the flasher motor. If something is wrong with my flashers can that keep the tails from coming on?

[simplyconnected]

Just about all of your wires have plugs and receptacles (even the headlight & ignition switches). That makes crossing wires nearly impossible. There are a few switches that have individual push-on connectors, like the Emergency Flasher Switch. Check the wire colors to be sure they are on the correct stabs.

Emergency Flashers should only control your stop/turn signals, not your parking lights. Is that what is clicking?

Two of your descriptions bother me. Dash lights and headlights should not flicker. You also indicated an audible, as the flicker was happening. That could be a self-resetting circuit breaker. Feel the breakers on your fuse box. If you find one that clicks, pull it out and look at the amperage written on it. If you can find another next to it with the same amp rating, swap them. If they both do the same thing, that indicates a short, so you need to troubleshoot. Warm or hot wires also indicate a short.

Don't buy any more parts until you prove a component is bad.

Continue using the test light with the electrical diagram. At some point in the wiring, the flicker will stop on one side of a component. I print out the schematic, and use colored pencils to trace wires. Then I cross them out as they prove them to be ok.

Use all your senses when troubleshooting: Look at the test light, feel and listen for the clicking noise, or warm wires. Plan your attack using the diagram and STICK TO YOUR PLAN. Don't get sidetracked until you prove a circuit all the way through. If you get sidetracked, you will be chasing all over. Start with something that is NOT working, and trace the wires from the light bulb to the power source. When you find that fault, you may also find the cause for other things that aren't working properly. Dont' be afraid to unplug receptacles; I have found corroded and shorted plugs.

A good test light indication is the truth. You may need to nick the insulation on a wire to test it. That's what they make electrical tape for.

If you get stuck, call me (248) 544-8834
- Dave Dare

[zx28]

The clicking noise im hearing and feeling is coming from the headlight switch itself. I read on the diagrams that there is an 18 amp breaker in the headlight switch itself; does that mean there is a short in one of the wires coming into the switch?

I ve been kinda a.d.d i guess, brainstorming to see where to start. im about to head to head to work and when i get off im going to prepare for battle and start tracing wires.

[simplyconnected]

...I read on the diagrams that there is an 18 amp breaker in the headlight switch itself; does that mean there is a short in one of the wires coming into the switch?...

It means the short is AFTER (downstream of) the switch.

I'm going to jump ahead of myself and ask you to take ALL your parking light bulbs out. Shoot for the Parking/Tail Light circuit (because it doesn't work). Then test the headlight switch. Sockets usually go bad before connectors. If you have 'extra' wiring from a trailer hookup, disconnect it. Headlight sw still clicking? Continue.

Disconnect the first plug after the headlight switch, and if it doesn't click, that's a good sign. Unplug the next one in the tail light circuit, and restore the first plug. Use this process of ellimination all the way to the end. That's the easiest way to find this problem.

If the switch starts clicking again, back up to the last plug. As you go, mark good plugs/receptacles in the diagram. You can number them on the print, while using masking tape and a marker on the plug/receptacle. - Dave

[simplyconnected]

I spoke with Eric tonight. He has nearly all of his plugs disconnected (headlights, tail lights, stop lights) and the headlight switch still flickers internally.

He's going to invest in a multimeter so he can chase grounds. I have a feeling one of his wires is pinched in a body panel or maybe a relay is grounded. We'll soon see.