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2015 Ford Focus ST
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Discussion Starter · #1 ·
Ok so it's a 2015 Focus ST.
Car unlocked got in and wouldn't start. Key/FOB not present. Accessories running. Could not shut them off with ignition push button. Tried Emergency start using center console, still no dice. Opening doors would not kill accessories. Disconnected Battery to get accessories to shut off. Got a warning on SYNC that needed to start car or shut down for battery.
Got second FOB reconnected battery terminal car fires up. Drove around no issue.
Later that day take car out and same issue. Not start. A few other things I noticed this time. Headlights wouldn't come on. Wiggled positive terminal saw headlights come on and started car. Then car sputtered and stalled. Wiggled again and started up. Jumped in car started driving home. Rear passenger taillight went out. Car sputtered and stalled.
When I wiggle the Mega fuse block at the front of the battery box car will start. When it goes to stall if I wiggle it can catch itself.

What the heck is going on. Does anyone have a wiring diagram for this car? I been reading Forums and every time someone seems to have had the same issue they didn't post the fix.....So frustrating.
Any help appreciated.
 

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2013 Ford Focus ST1
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Ok so it's a 2015 Focus ST.
Car unlocked got in and wouldn't start. Key/FOB not present. Accessories running. Could not shut them off with ignition push button. Tried Emergency start using center console, still no dice. Opening doors would not kill accessories. Disconnected Battery to get accessories to shut off. Got a warning on SYNC that needed to start car or shut down for battery.
Got second FOB reconnected battery terminal car fires up. Drove around no issue.
Later that day take car out and same issue. Not start. A few other things I noticed this time. Headlights wouldn't come on. Wiggled positive terminal saw headlights come on and started car. Then car sputtered and stalled. Wiggled again and started up. Jumped in car started driving home. Rear passenger taillight went out. Car sputtered and stalled.
When I wiggle the Mega fuse block at the front of the battery box car will start. When it goes to stall if I wiggle it can catch itself.

What the heck is going on. Does anyone have a wiring diagram for this car? I been reading Forums and every time someone seems to have had the same issue they didn't post the fix.....So frustrating.
Any help appreciated.
I would say start by checking the battery. These cars do funky things when the battery fails - and they do fail from one day to the next.......
 

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Discussion Starter · #3 ·
I would say start by checking the battery. These cars do funky things when the battery fails - and they do fail from one day to the next.......
I should have stated I have a new Optima REDTOP battery. No issues there.
 
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2017 Kona Blue ST1
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Broken fuse in the HVJB (high voltage junction box) mounted in front of the battery. Check that as power to you BMC may have been cut.

384825
 

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Discussion Starter · #5 ·
That diagram is quite useful thx.
Do these cars have corrosion issues with these connections?
 

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Those fuses are be damaged when changing the battery. Not saying that this is exactly your issue but it's the most common cause.

Let me know if you need anything else.

J
 

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Discussion Starter · #7 ·
Those fuses are be damaged when changing the battery. Not saying that this is exactly your issue but it's the most common cause.

Let me know if you need anything else.

J
Thx. I'll bring a meter to my dead car and OHM the fuses out.
 

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Broken fuse in the HVJB (high voltage junction box) mounted in front of the battery. Check that as power to you BMC may have been cut.
Off topic, BUT THANK YOU FOR POSTING THIS!!! I've been looking for a picture of this that you posted a while ago and couldn't find it. I've got a small project I want to use it for and didn't want to pull mine until I am working with it.
 

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My buddy had similar issues. Even though his terminals (on the wire) looked fine, we replaced them and everything started working again.

Sent from my IN2020 using Tapatalk
 

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Discussion Starter · #10 ·
My buddy had similar issues. Even though his terminals (on the wire) looked fine, we replaced them and everything started working again.

Sent from my IN2020 using Tapatalk
Which terminals exactly?
 

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The terminals actually connecting to the battery. Wiggle them and see if you start to hear solenoids and relays clicking. If you do start to hear them click with some wiggling, replace the terminals and you should be in better shape.

Sent from my IN2020 using Tapatalk
 

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Discussion Starter · #12 ·
The terminals actually connecting to the battery. Wiggle them and see if you start to hear solenoids and relays clicking. If you do, them and you should be in better shape.

Sent from my IN2020 using Tapatalk
Yah, that's what I seem to see. When i grasp the positive battery terminal and kinda wiggle the BJB, I hear the relay's lights come on and car will start. I sure hope it's just a loose connection in there. Going to go look in about a half hour. PITA to get to that BJB though. Bringing tools to take things apart. Sigh.
 

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Broken fuse in the HVJB (high voltage junction box) mounted in front of the battery. Check that as power to you BMC may have been cut.
does anyone know if there is a way to download these images as a jpeg or bitmap or something? I keep trying to save them for future ref stuff, but all I can get is some .webp file and they aren't images, nor will they open. I'm stumped
 

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Yah, that's what I seem to see. When i grasp the positive battery terminal and kinda wiggle the BJB, I hear the relay's lights come on and car will start. I sure hope it's just a loose connection in there. Going to go look in about a half hour. PITA to get to that BJB though. Bringing tools to take things apart. Sigh.
Sand the connections where the positive line meets up with the BJB. Make sure that the nut that clasps down to your BJB is tight.

Sent from my IN2020 using Tapatalk
 

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does anyone know if there is a way to download these images as a jpeg or bitmap or something? I keep trying to save them for future ref stuff, but all I can get is some .webp file and they aren't images, nor will they open. I'm stumped
WebP is a new lightweight image format for the web. They're not supported on Safari, so if you're on an iPhone or Mac computer, just download them from there. Otherwise you have to throw them into a converter online to turn them back into pngs or jpegs.

Sent from my IN2020 using Tapatalk
 

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WebP is a new lightweight image format for the web. They're not supported on Safari, so if you're on an iPhone or Mac computer, just download them from there. Otherwise you have to throw them into a converter online to turn them back into pngs or jpegs.

Sent from my IN2020 using Tapatalk
argh....
thanks man
 

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384826


So the BJB (battery junction box) along with the starter, BCM (body control module) and others are fed from this junction box (see above)

The enclosed box can encourage corrosion on both the battery terminals. The BMS (battery monitoring system) sensor is located on the Negative cable itself and is communicates over the single wire LIN BUS (local Interconnect network). The power for this sensor is a single white wire that attaches to the Positive post terminal directly. Should corrosion travel down this wire it has the potential to wreck havoc on the electrical system.

I have found that if you cut the wire back and crimp a ring terminal on it you can relocate it away from the battery box. This will help mitigate the potential for corrosion and odd electrical gremlins.
 

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Discussion Starter · #18 ·
I like this post. I'll have a look at modding this.
 

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Discussion Starter · #19 ·
So everything tight. No issues with fuses. .04kohm resistance across them.
Car fired right up.
Took main connection off and cleaned it
Not sure
 

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2017 Kona Blue ST1
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Cool. Be careful as I have seen the mega fuses physical crack internally causing intermittent connection issues. But poor / loose / dirty battery terminals will definitely cause issues as well.

Glad you're up and running!

J
 
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