Hello Everyone,

My name is Chris and Im up here in Snohomish Wa. Howdy to everyone!

Ive been following this forum for awhile now and it's obvious you guys definitely know your stuff

With that said, my wife and I just picked up a 65 F100. It runs like a top except for one small tick.

I was attempting to get at the ICVR on the speedo to replace and somehow the ignition switch stopped working? Meaning, I get no power to the switch. I cant even jump start the dang truck because turning the key to the ON position does nothing lol. Man i feel like a goob

With the ICVR out of commission, would this affect my ignition switch working?
I wonder if I should just run a fresh red/blue wire to get a good signal from starter relay?

Also, the starter relay has a black wire on the starter side along with the starter wire. What the hell is that for? It goes back along the firewall to driver's side and into the fire wall?

Any help would be much appreciated. We simply want the be able to start this baby again!

 

Do have an ammeter gauge or an idiot light? Is that black wire a large gauge? I have lots of wiring diagrams but I don't post pics. I know a lot of the guys here have them also and can post what ya need.

 

When you turn the switch to the on position, do you have power at all?

 

I have the ammeter gauge. When I turn the key to start I get zero power.

The gauge of wire is indeed the thick black one. Any ideas w hat its for?

 

Are you getting power at the battery? Head lights coming on, or anything else working?

 

I do get power at the battery and the battery side post on the starter solenoid, however no lights and no other electrical.

Question: Should that thick gauge black wire go on the battery side of the starter solenoid, or the starter side? If in the correct place, would that prohibit my lights from working?

Its really weird, im trying to figure how to get a signal to the starter relay via the ignition switch, however is there another wire giving the switch power? Or is the red/blue wire the one that feeds power to the switch?

These old trucks are a handful, but it seems like there is a sequence of how everything is arranged. I just can't tell which wire is supposed to supply power to the switch, at least if I did, I could trace it back or something

Hopefully this helps everyone understand the issue. Here is a pic of what im working with.

View image: 20140428 213214

So red/blue is the 'S' wire...is this the power? Or is it the Yellow that splices to black/yellow? I also have the pink resistor wire too and the green/black accessory wire that goes on the post.... am i missing anything? lol I cant image i did that much damage?

Is there a fuse somewhere besides the fuse box or something that could have fried? Im lost my friends.

 

One new development as doing research....

Looking at my starter relay, I have the typical battery, S, I, Starter setup. HOWEVER, there is a thick gauge black wire that runs along the firewall.

This was connected to the starter relay, however which side should it go? Battery or starter side? I always thought only the starter goes on starter side?

I assume this black wire is the accessory cable which would give power to the ignition switch and dash loom etc..

Unfortunately Im at work, not working lol so I cant take a pic or see it

Anyone think otherwise??

 

The big black wire DOES indeed attach to the + side of the relay. From the relay, it goes to a 70 amp circuit breaker that is also mounted on that same fender skirt. The circuit breaker looks kind of round with 2 metal threaded posts. From there (some have it, some don't that I have found) it goes to a 'junction block' which may also be mounted to the fender skirt. It is square. From there it goes up under the dash and through a 'hoop' (not a threaded post) on the back of the ammeter. The hoop picks up and senses current that is carried along that LARGE wire - which gives a read out on the ammeter. That wire at this point is the large black one.
After the ammeter, the wire splits into two wires. One is black/orange with goes to the headlight switch. The black/orange wire splits again into 3 wires. One that continues on to the ignition switch and plugs into the bottom of the switch. This wire is yellow. The other two of the 3 wires are Red and the other is Black/Green and both of those go to the fuse panel.
If someone would post a pic of the wire diagram for the lighting/gauges/wiper/------, you would see what I'm talking about. I know a lot of these guys have it, I just don't post pics.

Have you checked the fuses?
Have you check for broken wires? Looks like some of those wires are bent pretty bad.
You also might check to see if you have power at the large black wire at the end that is under the dash. If no power there, there is either a break in that wire, OR possibly the 70 amp circuit breaker is bad or possible loose wire.

 

The Masked Rider, many thanks!

Thank you that is exactly what I needed to know. I will correct my connections on the starter relay as soon as I get home tonight and report back!

I did check all the fuses and none are blown on the box. One of the prongs that holds in the bottom right fuse was rusted and broke off, but Im just going to get a new fuse box anyway. Would that give issue?

One last questions before I start actually working lol, With the ICVR removed from the dash, will I still be able to test everything to at least get power and have her start?
As I understand, the ICVR is only there to regulate power levels to the temp and oil gauge from 12v to 5v, thus not affecting the ignition function.

Am I wrong here? Do I need a new ICVR to get this thing started and/or tested?

 

the wire to the CVR did not affect the starter when I disconnected mine. don't know if this will print but I'll try

 

masked rider that was incredible answer. It took me weeks when I had to rewire my ignition switch and got lots of help here. but your answer was straightforward and concise. wish I had asked you.
pokermon - there are postings here of the wiring diagram if you can look around. Also a few posts how to build a CVR for about $5 from radio shack that works great
Good luck
Scott

 

Thanks Scott for all the insights! I actually got a hold of a black and white wire diagram which should be helpful

Ill look into making a CVR asap! I looked online and the lowest I found them is $25 shipped. Now that I know I can test everything without it this evening, I would definitely be open to making one myself.

More to come this evening, and thanks to everyone for sharing

Cheers!
Chris

 

The wire from the ignition switch to the Constant Voltage Unit (CVR) is Black/Green. It is attached to the center threaded post on the back of the ignition. From the CVR, it ONLY goes to the gauges to supply power. That wire is also Black/Green.
On another note, you mentioned rust at the fuse box. You also might have rust where the wire harness plugs into/passes through the firewall. Those pins sometimes get very rusty. A place well overlooked.

 

Thanks for schooling me on the CVR, peace of mind

Do you reckon I spray some WD-40 on the fuse box and the harness to help the connections? I could spray from under the dash as well as engine bay side?

 

I don't usually use WD for electronics unless its just to repel water. For real badly rusted pins, I use a drill bit that will fit in the holes BUT, you need to run the drill in reverse. Its only to clean out the rust. For the lighter parts, you don't need to do that.

I use a product called 'Deoxit D100'. Made by GAIG Labs. You can get it in D25, D50, D75 & D100. I always use the D100. Its used for electrical/electronics. It will dissolve corrosion on contact and keep it well protected. Its NOT cheap but will last a very long time. You don't need much. It sprays out in a buff - not a stream like most products. You hit a spot a couple times and it will start foaming up - dissolving the crud.
A good electronics place will carry it. Radio Shack might still carry it. They've gone through big changes in the last few years and don't carry much of anything anymore.