'01 7.3.. I'm having a strange wiring issue. I thought my batteries were dead, gauge read 8v, no crank etc but then all of a sudden power clicked on and the truck cranked over and started normally. I turned it off and tried again, and now its dead again and won't come back.

I hooked up my battery charger and it started doing a weird thing with KOEO where relays kept clicking on and of. I know its not my battery cables because I have the same voltage at the starter relay that I do at my batteries.

Probably next step should be get to the ignition switch and see if voltage is good there? Maybe the switch itself is bad? Thanks!

 

If your relays are clicking with KOEO you have either a cross-feed on the circuit that is not ignition controlled, a relay going south (this also includes the starter solenoid - which is actually a relay in disguise).

Do you have any additional wiring you've done? I had a guy with a radio on the PCM circuit feed and the keep alive memory on the (+), if the radio was on, the truck would not shut off, everything else would, but the engine wouldn't). Just an idea.

The harness under the sash and steering wheel column are suspect. So is the main harness under the hood at the distribution box.

 

Yes, there is a fair amount of really sketchy wiring from the previous owner, some of which is for remote start. I should probably check those wires out. I remember seeing the remote start wiring when I bought the truck and thinking "when this stops working it's gonna suck".

 

When you get your voltage from the battery, are you touching the actual battery posts - or the cables? Have you read the voltage from the battery ground post (not cable) to the chassis?


When the voltage spikes up and all is well, is this a number of seconds after turning on the key? Glow Plug Relay can do that.

 

Well I think the relay issue was just that I was right around 11.5V. I charged the batteries and now I get consistent power (so far) but when running my battery light is on. Maybe my alternator is bad....

I checked out the wiring and it seems good, 12+V at blk/org B+ wire at alt, 12+v at org/lt bl A wire.

Only questionable thing is the 11.7V at the lt grn/red wire at alt (key on). I belive this lower voltage is normal since it runs through the batt light.

Probably time to yank the alt and have it bench tested.

 

The Alternator can be charging and the Batt Lamp on the dash illuminated. There is a fuse in the under hood distribution box which controls the circuit for the lamp. Check your fuses.

With the truck running (operating temp) use a DMM to measure voltage from the B+ (Alt) to the Battery Ground. Should be reading greater than 13.5 VDC.

If the alternator is producing adequate voltage, changes are you have a resistance issue with the cables and grounds on the batteries; which will need to be cleaned.

 

Well I had the alt tested at auto zone and it failed at 11.5v.

Probably get a high output one from quick start. Are there any factory applications I could buy a large case 6G alt from to get some extra amps?

 

I was wondering if you still have your Ford and if you ever found the issue causing the random not starting issue?

 

Better to start your own thread with all the info relevant to your no start. Otherwise folks need to wade thru a bunch of old stuff to get to it.
Be sure to include general truck description (model year, AT/MT etc) and more detail about the problem and when it occurs. Plus anything else that changed recently, like you recently hit a moose or whatever.

 

Thank you! I am a newbie, if you couldn't tell.