Rear right side light not working/ reverse lights not working All lights in the back function when brakes and turn signals are applied though

Non functioning parklights when running lights are on/but turn signals work when applied

Left turn on when running are turned on/ no dash lights even after turning the ****. Also light and wiper washer light not working same for the air controls which quit lighting up
Hey Guys! I'm James, This is my first post on any ford forums! I'm 18 and I own and daily drive my 1977 4.9L inline-six F-100 custom to school and everywhere else. I've been working on it with my dad for a year and it has come a long way.
I'm currently having issues with my dash light and exterior lights as well. I've replaced all my dash light bulbs and both flashers but the 2 bulbs which light up the entire dash don't work same for the air controls and for the light that illuminates the lights and wiper washer controls. The left turn signal goes and stays on when I turn on my running lights on but still works when I indicate a left turn. My reverse lights don't work at all. The rear light doesn't work when the running lights are turned on but does work when the brakes and turn signal are applied. And the last issue is.... that my front park lights don't work when running lights are turned on but do when both side turn signals are applied.
I hope you guys can help me out and hopefully I didn't make it too hard to understand. I've also attached pictures

 

Good chance most of your problems can be traced back to either your turn signal switch or your bulb sockets . or both.

 

Most likely cause of your exterior lights not working , are the sockets . I replaced all 4 , 2 front ,2 rear , and removed the poorly installed trailer wiring on my truck to fix the same problem .
Dash lights are controlled by the headlight switch , but I think there is also a fuse for instrument lamps , as well as for reverse lamps, under dash , driver side .

 

Reviving an old thread. I'm having the same issue with my dash lights. No lights and turn signal stays on.

It blows the fuse after I replace it.

I've replaced the headlight switch and have changed the entire column and the issue persists. I guess the turn signal switches in both columns could be junk.

 

Try jiggling your turn signal stalk, and see if that changes the symptoms or makes them go away.

Do you think that anyone might've changed the instrument cluster or its printed circuit board? That could cause those symptoms if they put in the wrong one.

But the turn signal switch is still a likely culprit.

 

I've had my gauge cluster out, its the original and everything worked before. Even swapped it out for another used one. No change.

I ordered a new turn signal switch. I'll see if that helps when I get a chance to install it.

 

The fuse blowing seems fishy. Either there is a short circuit, or too much load on that circuit.
Are there any additional wires that might be tapping into that very low amp fuse? If not, the previous mention of the lamp sockets would be my next check. I've seen contacts get bent in such a way as they were either touching each other, touching the metal housing (I think ours are plastic though, correct?) or just touching another contact point that messes things up.

And checking grounds any time there is a strange thing going on with lights is always a good move.
The backup lights not working (was that only the OP, or is yours acting that way too?) could just be the neutral-safety switch dying.

Last, but not least, in case it wasn't mentioned check the entire run of wires along the frame. You're looking for pinches, burns, tears and anything that is not supposed to be there.
If the truck has dual exhaust, look for anywhere that the tubing passes close enough to the wiring to mess it up.
And sometimes there is a main harness disconnect along the harness, I believe almost all the way back. That connector gets buggered up sometimes. There are also aftermarket "jumpers" if that's the term (maybe "interconnect"?), that are used to tap (maybe "tap" is the word!) into the wires for a trailer plug. Do you have a hitch and electric plug? If so, follow those wires to see if they are part of the problem with the tail lights.

good luck!

Paul

 

Welcome! And welcome to fun with wiring!

1. Most likely, the reason the blinker light stays on is to indicate something is wrong with the system. Do the lights blink outside when you have them turned on? Does the right turn blink?
2. The reverse lights are connected directly from the transmission (or neutral safety switch) and run together. If both of them are out, it is probably upstream from the back of the truck. Check the plug (either directly into the transmission or the neutral safety switch if you have one)
3. The wires for the brake lights, tailights and turn signals are all different. Tailights come off the headlight switch. Brake lights come off the switch on the pedal. Turn signal comes off the turn signal switch. If bulbs and sockets are good, check at those places.
4. Headlights without side marker lights are usually bulb, switch, or wire not connected to headlights. They usually run in series.

 

On mine, turn signals and brake lights still work.

 

So you're only having the issue with the dash lights not working and the turn signal indicator staying lit?
Is the indicator lit anytime the key is ON, or only when the headlights are on?

If it's not exactly the same as the previous poster, give us a full detailed rundown of yours.

Paul

 

My side marker lights and taillights quit working. Ill start with my headlight switch

 

The side marker lights are usually connected in series. Meaning wiring goes from the switch to the headlight, and from the headlight to the side marker lights. There may not be a direct connection between the side markers and the headlight switch. It would go through the headlight harness first.

 

Exterior lights - using a test light, make sure you have juice going where it should. Lights on, you should have juice to each socket to work the running lights. Lights off, turn on your turn signals and make sure you have juice to the second base post in each socket for front and rear turn signals. Check each socket's ground wire (a bad front ground can affect the rear on the same side, remember - they are on the same circuit.) Make sure you have a solid connection between the sockets and the grounds... those grounds may look to be screwed in solidly, but if the connection from the wall of the socket to that ground wire is broken, no ground and you will get a wonky circuit. And check each bulb to make sure they work... they may be over 40 years old. Once you have done this, you will have a better idea of what you are looking for (like "no power to RR turn signal" or whatever) when you start tracing wiring.

 

When I got the truck no dash lights worked pretty much all I had was headlights. A lot of wire tracing and reading diagrams. I fixed my marker light issue this morning. The plug on the harness at the rear of the truck was the issue.

 

I clearly noticed in HoustonDave's post right above is :

Mentioning the word "ground(s)" a total of 5 times....

I cannot advocate enough above how important it is to have adequate and clean grounding, and also highly recommend superior grounding by installing larger main ground wiring and interlinking together, mounting to engine - frame - clip - body - cowling - starter - volt reg - etc. and coating all interlink connections so they never corrode - and one will never have these type of red green, jerry rig, cross wiring kind of looking functions in the first place.

I see enough times when dash lights and marker lights go out on our old Fords (like 194 bulbs).... If there are multi bulbs that have blown out or turned black (or have a short life span after replacing them) - that is usually an indication of BAD grounding somewhere...if none of the bulbs are blown at all and just do not function - I would lean more suspect towards a broken wire, connection, switch, or power issue.

Over 75 percent of the time when I see or hear someone tell me about funky lighting functions happening such as : my tail light doesn't do this but my other lights do that when I apply this or that, and that this won't work by itself unless I do this or that while this or that is on or off, etc. - I guarantee there is some grounding issues causing stuff like that.....then in some cases gets worse when a previous or current owner splices and jerry rigs other wiring and circuits to 'fix' a dysfunctional issue - which leads back to square one because there is still lack of grounding somewhere.

My superior grounding that is all interlinked in certain spots do count for 2 way, 3 way, and a few 4 way grounding circuits as I rarely have electrical issues at all.

My recommendation is to clean and fix all ground points and circuits FIRST and double checking by confirming each ground wire having full continuity, before tackling any one dysfunctional component at a time - that will eliminate an awful lot of time and guesswork once that is done.