Was out doing a tune up on the truck. Started it to adjust my carb. It died. So when I went to restart it, I lost all electrical. No interior, no idiot lights, no headlights, no flashers, no nothing. Battery is good and new, checked the three fusible links near the solenoid, all have 12 volts, checked the wire going to the altrernator, 12v, pulled off teh ignition swith harness and check for voltage there, have none on any wire. I didn't do anything else that I can think of. All I did was turn teh key, it clicked like it was gonna crank then nothing, as though someone removed the battery. tried another jsut for sure, and still nothihg. only thing confusing to me is while I was checking voltage on teh regulator, the 'I' terminal has only 8 volts on it, and it constantly varies between 8-9 volts, other than that, I have no clue where to go next. help??!! P.S. All fuses in the fuse box are good.

 

There should be more than 3 fusible links. Is the battery brand new and did you check the batteries voltage? it might be a bad battery. pull all the fuses and check current (amperage) at each terminal. If there is a short at any circuit you will read amps. I just had to replace my headlight switch because it was killing my battery (internally shorted) every time I turned the truck off. other than that it could be real simple, maybe you just detuned the carb too much and the idle is too low. sorry if this is no help, I am just basing this thread on my own limited experience.

 

Check your battery cables including the ground connection to the engine block.

Some people replace just the cable ends and leave it at that; copper exposed to the elements corrodes (turns green) and this corrosion permeates inside the cable, beneath any insulation.

 

if there is more than 3 I have no idea where they are. I cut insualtion on the links and get power on both sides of the green, orange, and the one thats on the big solenoid. I get power on the alt terminals as well. Battery is new and was replaced with another. Have checked cables as well. Just cannot figure what is going on!!

 

And the headlights worked before?

 

everything worked before. I just went and load tested battery, its good. should I be getting power at least to the big wires on teh ignition switch plug as well? getting nothing there.

 

If you do not have any headlights, then your problem is out near the solenoid(starter relay) where you checked the fusible links. The headlights get their power directly from a fusible link out there.

If the headlights do not work, make sure you leave the switch pulled out all the way before you start checking things with your meter. You need to load the circuit down before you do any voltage checks.

If the headlights come on, but then go out when you try to crank it over, you have a bad connection or bad wire somewhere near the battery or the solenoid. If this happens, do your voltage checks while someone inside tries to crank it. Again, you cannot accurately pinpoint the problem without a load on the circuit.

 

I have no headlights, no interior lights, no nothing... I have power on both sides of the orange and green fusible links, voltage on the link that comes directly off the soleniod (pos batt cable side). redid my ground and power battery cables. still nothing. Unhooked teh ign switch harness, no power on any wire there. I checked the links by shaving insulation off down to bare wire, did the tug test as well. trying to follow schematic on haynes manual, not a good schematic, but doing best with it I can.

 

I checked and have power on teh engine side of the big yellow wire. by the time it gets to the ign switch plug it dissapears. I have no power on any terminal on that plug. What am I missing?

 

Where are you placing the negative lead of your meter? To the neg battery post I'm guessing.. And the lead is too short to use it inside so you are using another body ground.. Right?

If the above is correct check BOTH ends of your neg battery cable again pay close attention to the frame ground and the engine block..!!! I'm betting on a bad ground...

 

i had a similar problem with my pickup, turned out to be a bad battery cable, couldnt see the break in the cable until i removed it. installed a new cable and havent had a problem since.

 

While outside, yes, the neg cable, on teh inside, was placing it on the steering column, and any other place I could find a ground. As for ground cables, I have one cable from battery neg to the engine block. thats all I know of. been like that since I got teh truck about 2 years ago.

cables and terminals are relatively new, and I went over them again while I was trouble-guessing this mess.

Does anyone know where I can get a decent schematic?

 

There HAS to be a body ground somewhere or else nothing is gonna work.. There should be a wire going from the engine to the body somewhere. or from the battery to the fender close to the battery...

Try making a jumper that will reach inside for a ground then check for voltages again, bet you find they are there... This will prove the bad ground theory...

 

So if I run a wire from the neg post to my VOM's neg, then check the ign switch plug I should have power,, right?

 

It would help to know which engine we are dealing with, and if your truck has ammeter and oil pressure gauges, or idiot lights. The trucks are wired differently depending on these factors, including grounds.

You should not shave the wires down to bear metal to test them. This will leave them wide open to possible severe problems later.

Depending on the gauge system you will have 3 or more fuse links.

Trucks with ammeter and oil pressure gauges will have 3 fuseable links.

One link comes off the starter solenoid. The other 2 are on the passenger side fender. Green/Orange.

To check these links properly, you should disconnect the battery and use an ohm meter.

--------------------------------

As for the ground, you should have a firewall to engine ground cable on the driver's side. make sure it's clean and tight between the engine and the firewall on the cab.

On V8's the negative battery cable hooks to the engine block. Make sure this is clean and tight between the engine and the battery.

On 300-6, the negative battery cable hooks in two places. One place is inbetween the cable length and the frame. About mid way through the cable there will be a tang that hooks to the frame. this is the frame ground. The other end of the cable hooks to the starter bolts that hook it to the bellhousing. Make sure these are clean and tight. (If the factory original cable has been replaced you may have lost the battery to frame ground tang. Run another seperate cable from the engine block to the frame if this is the case.)

Make sure all these grounds are clean. IE: Remove them sandpaper the connections, replace the cables if in doubt of their condition, and go from there.

If still no power to the ignition switch, then you will have to slowly trace the Yellow wire from the switch back, untill you find power.