intermitent power to ignition
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From: Virginia
This is going to be very hard to trace. But I just remembered a good test. Next time it throws a fit, turn the headlights on and see if they look ok. If it's daytime, hopefully you have someone with you that can watch the headlights while you try to crank the engine. If the headlights go dim, or stay bright while you are having this problem, it could possibly narrow down the problem.
What we are doing with the headlights is using them as a crude voltmeter. The headlights are hooked directly to the wiring at the starter relay.
If you have your problem, and your dash lights go dim, and the headlights go dim too, then we know the problem is out in the engine compartment near the starter relay or the battery.
If they stay bright when the dash lights go dim, and even stay bright when you turn it to start, then we can figure it's going to be deeper in the circuits like you were thinking in your last post.
What we are doing with the headlights is using them as a crude voltmeter. The headlights are hooked directly to the wiring at the starter relay.
If you have your problem, and your dash lights go dim, and the headlights go dim too, then we know the problem is out in the engine compartment near the starter relay or the battery.
If they stay bright when the dash lights go dim, and even stay bright when you turn it to start, then we can figure it's going to be deeper in the circuits like you were thinking in your last post.
Fleet Owner
Joined: Sep 2005
Posts: 28,609
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From: Lake Tahoe, Nevada
Originally Posted by alz
Battery connections are good and tight. Less than a year ago I replaced the entire battery cable assembly with the Ford replacement. Positive, negative and all grounds. It came as a whole unit, not cheap from the dealer. I was thinking, what is the next thing to get power when key is turned to ON pos after the ign switch. Is there a relay? Maybe fuel pump relay?
As to the cables, there is no mimimum time for a connection to develop some corrosion. I would clean them up anyway just on suspicion.
A lesson that I have learned over and over: New means new, it doesn't mean good.
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Fleet Mechanic
Joined: Nov 2004
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From: Michigan
Thanks for the suggestions. The next time I have a problem with it I'll give it a try. When this happens, I have no power in the cab when I try to start the truck. I also noticed, when this happened, the gear selector shifted out of park without pressing the brake. Is this mechanical or electrical? I was trying to see if there was a short by moving the tilt colum and steering wheel. Also, when the truck does start, it runs fine and you would never suspect anything wrong. I'll let you know about the headlights trick.
Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
Originally Posted by alz
Just remembered something else. The radio lost it's memory, but the battery never went dead. Just the power in the cab from what I could tell.
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Fleet Mechanic
Joined: Nov 2004
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From: Michigan
I think that the whole power dist box loses power because the fuel pump doesn't run either. Like when you turn the key to the ON pos and you here the pump run for about two or three seconds. If you leave the key in the ON pos for a while, I eventually here some clicking under the hood, kind of like a relay trying to close with bad contacts. Shortly after this the dash lights up (meaning, the CEL, battery,ABS,and seat belt lights come on like normal)and everything has full power and the truck starts like nothing ever happened.
Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
Where the Fuse Link A & B bolt on to the starter relay, make sure it is clean and a good connection.
If that is not it then you are going to have to pull the Engine Compartment Fuse Box up and look under it at where the big Yellow wire connects to the bus, that is more than likely where the bad connection is.
If that is not it then you are going to have to pull the Engine Compartment Fuse Box up and look under it at where the big Yellow wire connects to the bus, that is more than likely where the bad connection is.
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Fleet Mechanic
Joined: Nov 2004
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From: Michigan
Well here we are again. I haven't been having any problems and it's the holiday again and it happens. Turn the key and everything goes dead. I turned the headlights on and what I could see, was that they were not on. I turned the key again and she started right up and the lights went bright. I'm thinking that the problem is at the starter relay on the firewall since this is only an issue when starting. I will remove the connections on the relay but as of now they seem good and tight. Any comments Franklin2 or Subford or anyone else?
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From: Virginia
Ok. No headlights. You are right, it's going to be at the starter relay connection that goes to the battery, or that cable is bad going from the starter relay to the battery +, or the battery has a bad connection. It could also be the ground cable to the battery - is bad, or the end at the battery or the engine block is bad, or it could be an intermittent problem in the battery. I can't remember if you had replaced the battery or not.
It sounds like the bad connection is welding itself together and working for awhile before it quits again. Or you have a very rare battery problem.
It sounds like the bad connection is welding itself together and working for awhile before it quits again. Or you have a very rare battery problem.
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Fleet Mechanic
Joined: Nov 2004
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From: Michigan
Monday I replaced the relay and made sure to have good connections between the wire terminal ends and the posts. The Battery cable is relatively new and is a factory replacement not one pieced together. Battery seems good, cranks strong when not having this problem. I have not rechecked the grounds on the block and chasis. If the relay is not where the problem lies, that is my next stop.