Multiple electrical issues

Tiny
TRUECOUNTRY
  • MEMBER
  • 2011 FORD MUSTANG
  • 3.7L
  • V6
  • 2WD
  • AUTOMATIC
  • 105,000 MILES
All this happened at once. I started the car and could not get shifter to move from park. The parking brake light is on, low tire pressure light is on, radio, headlights, turn signals, power windows, power locks, trunk release, blower motor, and dome light are not working at all. Checked all fuses in kicker panel.
Thursday, February 17th, 2022 AT 4:18 PM

11 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

Chances are there is a fuse in the battery junction box that has failed causing a power loss to the central junction box in the vehicle. Interestingly, the headlamps are powered from the battery junction box, but power continues from there to the interior box.

Since the power windows don't work, we must have lost power before that fuse. Power is provided by fuse 31 in the battery junction box. See pics below.

Do me a favor. In the under-hood fuse box, I need you to check a few fuses to see if they are good. If they are, you need to confirm there is power to them. Check fuses 18 and 29. If you find the fuse is good and there is no power to them, go to fuse 31 and do the same thing.

Pic 3 shows the fuse locations.

Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

If these all test good, we will need to check the accessory delay relay.

Let me know what you find,

Joe

See pics below.

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Thursday, February 17th, 2022 AT 5:28 PM
Tiny
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Checked the fuses and all good. Exchanged the accessory delay relay in the central junction box.
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Friday, February 18th, 2022 AT 10:45 AM
Tiny
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I also noticed the windows do drop opening and closing doors they go back up.
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Friday, February 18th, 2022 AT 2:16 PM
Tiny
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Okay, I got Autel hooked up and these are the codes: b1218:51-8a, u0140:87-0a, and u0140:2f.
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Friday, February 18th, 2022 AT 3:10 PM
Tiny
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  • MECHANIC
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The codes you have are related to the can-bus, the smart junction box, the body control module, and so on. When you checked the fuses in the SJB, did they have power to them? If the SJB lost power, it can be the issue with the BCM.

Let me know,

Joe
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Friday, February 18th, 2022 AT 4:09 PM
Tiny
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Yes power to all fuses at sjb.
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Friday, February 18th, 2022 AT 5:01 PM
Tiny
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  • MECHANIC
  • 109,747 POSTS
Hi,

Okay, then at this point, I feel either we have an issue with the can-bus to the BCM or the BCM has failed. In the case where multiple modules DTCs are stored, the diagnosis will shift to the CAN bus. It could be related to the module itself, so confirm the wiring to it is in good condition and the connectors are not loose.

Is the scan tool able to communicate with the BCM? If there is no communication ability, then I need you to look through the directions for checking a no communication/can-bus information below.

The BCM is located in the right rear of the luggage compartment. I need you to locate it. Next, locate the gray wire with an orange tracer and the violet wire with an orange tracer. These are the can wires to the BCM. Inspect them. Make sure they are tight and undamaged. Also, confirm the gray/orange has a 2.5v signal to it.

If they appear good, try a hard reset. Disconnect the battery negative terminal and allow the vehicle to sit that way for at least 5 minutes. Reconnect it and there is a chance it will resolve any issues within the can network.

Let me know what you find. Also, the last two pics below show the two wires to the BCM I am referring to and the BCM. The last pic is a pinout of the connector at the BCM. I highlighted the two pins related to the CAN.

I hope this helps. Let me know if you have questions.

Take care,

Joe

See pics below.
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Friday, February 18th, 2022 AT 7:25 PM
Tiny
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Okay, started unplugging the sjb after I unhooked battery and noticed two small, corroded places on two different plugs cleaned them with electrical cleaner and put a little dielectric grease and reconnected sjb and battery and car is back up and everything is working now. Next is seeing where the water came in to get it wet. Thanks, Joe, for your help.
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Saturday, February 19th, 2022 AT 2:12 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

Thanks for the update. I'm glad to hear you got it fixed. Today's vehicles are becoming more and more complex. LOL

Take care and please feel free to come back anytime in the future. You're always welcome here.

Joe
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Saturday, February 19th, 2022 AT 2:19 PM
Tiny
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Hi,

Yes, sir I see that complex a lot but I'm heavy equipment mech twenty plus years and don't have diagrams like you have for autos that's why I asked here. Thanks again Joe.
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Sunday, February 20th, 2022 AT 5:46 PM
Tiny
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  • MECHANIC
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Hi,

You are very welcome. Please feel free to come back anytime in the future if you need anything. You're always welcome here.

Take care,

Joe
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Sunday, February 20th, 2022 AT 9:16 PM

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