Weird NO START condition

[BRIANGEE]

2003 Expedition
EB
5.4L 2V
165K miles

Battery is good. Let me say that again from the get go - battery is good. It's been tested at two different parts stores and when I put it in my other truck it starts like a dream.

Normal battery voltage until you key on engine off. Voltage will drop to 5 or 6 V - this is w/o cranking. Lights on the dash will randomly come on and off, some come on very dim, fuel pump will continuously run (not just 2 second prime) although very weak because of the low voltage. If you try to start you will get crazy relay action, no starter clicking or anything just more electrical wackiness. I've been examining grounds all night but to no avail. Everything looks good so far. When I got done testing for the night I went to disconnect the battery and the negative terminal was really hot.

All fuses are good. I'm checking out wiring diagrams again for further test points but wanted to see if anyone had any leads in the mean time?

Thanks,

 

[stamp11127]

You have a BAS (big azzed short) - the hot battery terminal is the clue. Inspect the post battery cable for stg.

 

[1955moose]

Stamp he said the - was hot. Could he have a loose or missing ground?

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[Habbibie]

Stamp he said the - was hot. Could he have a loose or missing ground?

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No not a bad ground Moose, he's having too much electrical draw somewhere, my guess that either you have a defective solenoid with a partially-shorted activation coil or as stamp said short somewhere on the positive side

 

[BRIANGEE]

The strange thing is EVERY problem I have with this vehicle is intermittent (even leaks! LOL) . It will work fine then BOOM! Gotcha!

I thought I had it figured out with the fair amount of corrosion build up I discovered in the negative battery terminal. I cleaned it up and it started. I thought maybe that was it until I noticed the parking lights were on by themselves. I thought I would turn the motor off and see if they remained on then it wouldn't start again! LOL. So, where I'm at right now is I've changed out the negative battery terminal with a fresh one - everything is fine for now but we'll see when this beast strikes again.

I was trying to track down the thick negative battery cable - it looks like it just runs down the alternator with a few offshoots on the way. I was suspecting something was sticking w/ the alternator but then it would cause a draw all the time since it's always hot and that's not what happens with mine. There is a massive voltage drop only when the key is in the on position - and then again, only when it wants to act up which is the frustrating part. It was acting up nonstop until I changed out the terminal so hopefully I'm on to something.

 

[Habbibie]

Check the resistance of the positive cable to as far back as you can... from terminal point B, B to C, C to D and so on. you should maintain a 0.0-0.3 ohms of resistance the entire time, any more and I'd have a suspect

 

[1955moose]

We had a member a few weeks back that had a weird starting problem. Turned out to be his starter relay on firewall.

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[BRIANGEE]

We had a member a few weeks back that had a weird starting problem. Turned out to be his starter relay on firewall.

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Hmm... I like it. I'll have to find the location and next time it acts up that will be the first place I check.

 

[ThatOneMike]

We had a member a few weeks back that had a weird starting problem. Turned out to be his starter relay on firewall.

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pictures of this relay?and its location?

 

[stamp11127]

Since you changed the terminal that tell me the insulation has been removed and there is some wire exposed to the elements. If the wire doesn't have that "fresh shiny copper penny look" then there is corrosion in the wire. The more corrosion the higher the resistance, which in English means, lower voltage to the starter.