Did a Bad Thing
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Tuned
Joined: Jun 2006
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From: Graham WA
Did a Bad Thing
I feel like an idiot, but, we all make mistakes!
I installed my battery backwards (+ cable to - term, and visa versa). Before I did that the engine cranked ok, but my fuel pumps were not working.
Now, it won't even turn over. So I replaced the starter relay. That didn't help. The fuses in the fuse box are all good.
What have I likely damaged? Is there an inline fused link I have likely fried?
Dumb Me
I installed my battery backwards (+ cable to - term, and visa versa). Before I did that the engine cranked ok, but my fuel pumps were not working.
Now, it won't even turn over. So I replaced the starter relay. That didn't help. The fuses in the fuse box are all good.
What have I likely damaged? Is there an inline fused link I have likely fried?
Dumb Me
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From: Virginia
What year are you working on? Depending on that, yes you may have some fusible links that are burnt in two.
Go back to the starter relay. Look at the large terminal that goes to the battery +. On that same terminal with the large bat wire, there should be one or two other smaller wires. These power the whole truck. Follow these smaller wire(s) down, and you should run into some colored rubber things in the wire. These are the fusible links. If you keep following the harness, you may find some more down the line were the power splits off to feed other parts of the vehicle.
Go back to the starter relay. Look at the large terminal that goes to the battery +. On that same terminal with the large bat wire, there should be one or two other smaller wires. These power the whole truck. Follow these smaller wire(s) down, and you should run into some colored rubber things in the wire. These are the fusible links. If you keep following the harness, you may find some more down the line were the power splits off to feed other parts of the vehicle.
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Tuned
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From: Graham WA
What I did, reversing the terminals would send power directly to the starter solidoid which is part of the starter, would it not? And the other side would be grounded. So I thought it was probably the relay. But no!
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From: Virginia
You should have a fusible link right there at the starter relay. If not, then you might have to follow the harness down some to find them.
The starter relay large terminal that goes to the battery + is the spot where the factory hooks to the bat + for all power to the truck. This includes the alternator. There is a chance you have run current through the alt backwards, burning it up too. But you won't know that till you get the fusible links fixed to repower the truck. If the fusible link burnt in time, you might not have any trouble at all.
The starter relay large terminal that goes to the battery + is the spot where the factory hooks to the bat + for all power to the truck. This includes the alternator. There is a chance you have run current through the alt backwards, burning it up too. But you won't know that till you get the fusible links fixed to repower the truck. If the fusible link burnt in time, you might not have any trouble at all.
Last edited by Franklin2; Nov 10, 2006 at 09:10 PM.
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From: Rural Norfolk, England
It will certainly have resulted in a high current through the alternator, as the rectifier diodes will have been forward biased in chains of two across the reversed battery. If you're lucky, the fusible link will have blown before the high current had a chance to take out one or more diodes.
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Tuned
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From: Graham WA
Would the alternator burnout cause a break in the circuit such that the starter would not get any power to turn it over?
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Fleet Owner
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From: Easton,Ks
Originally Posted by E30tdf
Would the alternator burnout cause a break in the circuit such that the starter would not get any power to turn it over?
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From: Easton,Ks
Originally Posted by E30tdf
This is an 1986 F250 with Duraspark II ignition. Carberated 460. Should I untape the wire harness to find these fusible links?
One of the small terminals goes to the fuel system and the other goes to the Ignition Switch byway of a safety switch.
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From: Easton,Ks
Originally Posted by E30tdf
Then, I'm inclined to think it took out something in the starter, ignition, run circuit. Is it obvious from a visual inspection that the fused links are blown?
Also if you jumper a wire from the POS side of the battery to the small terminal of the starter solenoid that had the red wire with a blue stripe on it the engine should crank.
Make sure it is out of gear or in park when you do this.
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Tuned
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From: Graham WA
By using a volt meter I have determined that at least one fused link is damaged in the harness to the alternator. With the wire coming off the hot side of the starter relay terminal I checked for voltage at the alternator terminal and there was no voltage.
So assuming that the fused link is blown, does one just patch in a new fused link, or go to Ford for a new harness (at least that portion going to the alternator)?
So assuming that the fused link is blown, does one just patch in a new fused link, or go to Ford for a new harness (at least that portion going to the alternator)?
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From: Easton,Ks
Originally Posted by E30tdf
So assuming that the fused link is blown, does one just patch in a new fused link, or go to Ford for a new harness (at least that portion going to the alternator)?
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Tuned
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From: Graham WA
Unfortunately here in WA it is getting dark by 5:00 PM now and this rig is outside. Also it is raining (what RAIN in Seattle area....what a surprise) as this is probably the wettest month. SO, it may be a while until I get to work on the truck. Thank goodness this is NOT my DD. Thanks to all!