So I have lost all power to the truck....
A little back story, last Saturday my dad came up to take my truck to store at my parents place since I will be in a rental until my new home is built. Well anyways we pulled it out of the garage and he took it around the block with no issues. he parked the truck in the driveway, shut it down and we checked a few things, then I hopped in and went around the block then pulled it back in the driveway, shut it down. after about 10 mins of excitement of driving we decided to take it around the block one last time before the 2 hour journey to my parents, well when I got back into the cab to start it, I got nothing....no crank, no lights, no dash lights.....absolutely nothing. we go from driving it around to it just not responding at all. the next day we tried to trace what the issue could be, started with the battery(replaced it)....nothing. thought maybe the starter solenoid(replaced it)....nothing. thought maybe the voltage regulator(replaced it)....nothing. noticed a 1 fuse on the fuse block under the dash was blown so we replaced it, but that wasn't the source. we tried using a jumper wire on the starter solenoid to crank it over and it turned over but wouldn't stay running...just died as soon as the jumper wire came off.








in the end we are lost on what the issue could be, especially going from a running truck with lights etc to absolutely nothing.


any idea/suggestions?

 

My first guess would be a bad ignition switch, but you need to track it down. Does the horn work? Do you have a volt meter?

 

the horn I don't believe worked since I got the truck. I do have a volt meter and I tested the solenoid to see if it had power to it, it does...I checked the voltage regulator and it has power.... I checked the plug at the ignition switch, and it has power but doesn't mean the switch couldn't be bad. its the only think I haven't replaced electrical wise that pertains to the starting sequence..... would this switch being bad cause no dash lights or headlights?

 

I'd suspect the ignition switch first.

With the ignition in the off position you shouldn't have any voltage across the smaller or across the larger connections on the solenoid. Once you have someone turn the key to the Start position then you should get voltage across the smaller terminals which energizes the solenoid and moves the internal slug to contact the larger terminals together so then you should get voltage across the larger terminals which energizes the starter motor.

If you have someone turn the key to the Start position while you measure the voltage across the smaller terminals - if you don't get any change in voltage then it's likely the switch or the wiring between the switch and the solenoid.

Chad

.

 

There is a 66 F100 diagram here:
http://www.fordification.info/tech/i...sterwiring.jpg

Besides the ignition switch, about the only other place where everything comes together is the plug through the firewall. Possible but doubtful. So I'm sticking with the switch at this point.

When you turn the ignition switch to "on", you should get voltage at the coil. Without that, the engine won't run. From your description, you aren't getting voltage to the coil in the 'on' position, which is why it dies right away when you start it by shorting out the solenoid. So you may be getting voltage to the switch, but not through the switch.

 

I would check all the grounds first. Especially the battery ground. Just back off on the bolts a little and re-tighten them. If that doesn't help try the harness plug on the firewall. That black wire with the yellow stripe is the main power feed to everything. Be careful with that plug they can get corrosion in them and become very difficult to separate without breaking off the pins. Electrical problems are just a matter of elimination and yours sounds like it is a complete loss of continuity somewhere.

 

One other thing to try if your voltmeter is really a multimeter - set it to the ohms or continuity setting and probe from the center of the battery negative post (not the battery cable clamp) right dead center - and the other lead to various places (bare metal) like the chassis, engine block, negative side of the solenoid and make sure any place that you probe that should be a ground reference is a very low resistance between it and that negative post of the battery.

Chad

.

 

Ordered an ignition switch and will pick it up today in preparation for the weekend to work on this thing

so if it is the black wire with yellow strip that is the problem how do you go about fixing It?

 

This picture is an under dash harness that I have been mining parts out of but if you look you will see the firewall plug with the Blk/Yel wire. That wire goes to a splice point in the harness at that point the Blk/Red wire goes to the light switch, the yellow wire goes to the ignition switch the red one goes to the cigar lighter fuse. As you can see if you have power to that plug the lights will work and the cigar lighter will work regardless of the ignition switch position. So my assumption is your problem is not inside the cab. First you need to make sure you are getting power to the Blk/Yel wire where it is connected to the junction block or the solenoid or where ever it hooks up. If so then pull the plug at the firewall and clean the connections and check for power there.
If your plug is no good you can just splice around it. Or get a new harness. But it could be you just aren't getting any power to it. A picture of your wiring would be helpful. Good Luck!

 

I have a question. Does your truck have the amp and oil pressure gauges? I'm asking because if it does there is a fuse in that circuit that will shut you down completely if it blows.

 

If you have power but not the starting circuit, maybe a neutral safety switch if its an auto trans...? But definitely could be the ignition switch

 

When ya ain't got nothin', ya got nothin' to lose. Wait, that's not it. Think about it though...

One minute you're cruising, the next there's no electrical anywhere - no lights, no dash no nothin', it should be simple to find and fix because it's a major connection. Check for loose and corroded cables &c. Try wiggling wires harness and connections.

 

^ this

I'm thinking something primary as well. chassis ground, something like that. if you go from running to ice cold everything, that'd be my very first set of tests and re-tightening.

 

Starter wire loose?

One of my employees changed the starter on my daughters 75. worked fine. One day later, and 25 miles away from home, she said it would not start. Nothing. Dead. I drove up to find starter wire on starter was loose.

 

Yea! That's what I been trying to say.