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Car will not start

Tiny
ELCINCOCINCO
  • MEMBER
  • 2010 FORD FUSION
  • 2.5L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 180,000 MILES
Oh man where to begin, car doesn’t start. So I replaced the battery and no luck, replaced all the relays and no luck, started checking the small fuses with light and noticed that there was no power to fuse 45-49 and those fuses are injectors, PCM, General Powertrain, ignition coils, and other components. Buddy said it could be the PCM so went ahead and replaced the PCM and nothing. Checked power to alternator and starter and there was power there. Grounds look good and all cables as well. Now I checked the power in the interior fuses and the ignition switch fuse keeps blowing? All your help is greatly appreciated! It’s the wife’s car and it had battery issues and would have it jumped all the time, I’m assuming they attempted to jump it with the cables backwards but she assures they didn’t.
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Saturday, April 17th, 2021 AT 4:52 PM

9 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

If there is no power at the fuse, the PCM isn't the cause. Power to the PCM comes from the fuse.

As far as fuses, the ones under the hood are important. And yes, one of them powers the PCM. See pic 1

Next, I just want to confirm it is fuse 27 in the SJB that is blowing. See pic 2. Is that the fuse? Do you have to turn on the key for it to blow? If that is the case, disconnect the ignition switch and install a new fuse to see if it blows. Let me know the results.

Also, let me know if this is a hybrid. I'm looking through the wiring schematics (power distribution) and the two models are different.

I will watch for your reply. Also, fuses 45 - 49 seem to be tied into the ignition switch. So, if fuse 27 was an issue, that may be why they had no power. I need to know if fuse 27 blows as soon as you install it. If it does, chances are the switch is bad. If it doesn't and requires you to turn the key on, we have several circuits to check.

Let me know. Also, here is a link you may find helpful.

https://www.2carpros.com/articles/how-to-check-wiring

Let me know if it is a hybrid as well.

Take care,

Joe

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Saturday, April 17th, 2021 AT 8:18 PM
Tiny
ELCINCOCINCO
  • MEMBER
  • 5 POSTS
Yes, it’s fuse 27 that keeps blowing and no, the car is not a hybrid. I tried it this morning, I disconnected the ignition switch and put the new fuse in and it did blow it a soon as I put it on? Maybe it is the ignition switch then?
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Sunday, April 18th, 2021 AT 9:10 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
If the switch was disconnected, then the problem is between the fuse and the switch. Check wiring near the switch for any damage, make sure none of the connectors in the plug are damaged, and check near the fuse box as well.

Let me know.

Joe
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Sunday, April 18th, 2021 AT 5:14 PM
Tiny
ELCINCOCINCO
  • MEMBER
  • 5 POSTS
Okay, just got back and I checked all the connections from the switch to the fuse. All the wires and connections around the fuse box, and the other wires and connections in the same area, and everything looks fine. Any other suggestions?
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Monday, April 19th, 2021 AT 5:36 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

If the fuse blows as soon as you put it in and the ignition switch is disconnected, there has to be a direct short. What I need you to do next is check for a short to ground. Disconnect the battery and remove the fuse. Using a voltmeter or multimeter, probe the prongs where the fuse goes and see if there is continuity to ground. Again, have the switch disconnected.
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Monday, April 19th, 2021 AT 8:39 PM
Tiny
ELCINCOCINCO
  • MEMBER
  • 5 POSTS
I had no continuity to ground on fuse 27 nor any other fuse.
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Friday, April 30th, 2021 AT 9:17 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Check the wiring at the switch that was disconnected to make sure nothing is bent or allowing a short. Since it blows with the switch disconnected, the short has to be between the fuse and switch.

Joe
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Friday, April 30th, 2021 AT 8:00 PM
Tiny
ELCINCOCINCO
  • MEMBER
  • 5 POSTS
Sorry I took forever to answer, I was out of town because of work. So the wife called an electrical mechanic and diagnosed the car and said the interior fuse box was fried. He did mention that if I replaced the fuse box that I’d have to take it to Ford dealership or a shop that has the equipment to “flash” the new fuse box to the car. I can’t seem to find any new ones but I did find a ton of used ones, can I put a used one on the car?
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Friday, June 11th, 2021 AT 2:17 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

If the smart junction box is bad, he is correct. If you purchase a used one, it will already be programmed for the vehicle it came from. I don't think they can be cleared.

As far as replacement, take a look at the attachments below. I highlighted the two sections which discuss programming.

Let me know if I can help in any way.

Take care,

Joe
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Friday, June 11th, 2021 AT 9:36 PM

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