BCM not working

KEVIN BOYCE

MEMBER
2015 JEEP GRAND CHEROKEE
6 CYL
4WD
AUTOMATIC
55,000 MILES

(To begin, I will respond with updates regardless of the outcome. It's very frustrating to read forums and get so close to the end, but the owner never gave the final results)
I noticed a couple of days ago my passenger side door was not locking. I had to manually lock it and could only open it from using the inside handle. Through research and YouTube, I learned how to take the door panel off and look at the inner workings. After 5 hours of flash-lighting, revisiting YouTube, checking wires. I gave up and put the panel back on. Everything continued to work the same, except the passenger door (still not locking or unlocking using the key fob, or interior controls). I did however notice the clicking that was coming from the passenger foot-well.
With my headlamp on I got down on the floorboard and took off the carpeted cover that is just below the glove box. I was able to locate several plugs/connectors/pins (whatever you would like to call them.) When I pushed the lock button (on either the driver side or passenger door) I could hear the click and it felt like I could feel which pin was making the licking sound. So I carefully pushed in the tab, pulled down the latch and released the plug from the port. (This seemingly controls, windows, door locks, lights etc, )
Making sure all the wires were inserted correctly with no breaks, I went ahead and put it back in, because it didn't reveal anything. And that's when it went from a small issue to a big issue!
Now none of the doors respond (still clicking when you push the button), dome lights won't come on when you open the door, radio won't turn off when the car is turned off (it has to time itself out), my trunk is locked and now I can't open it, and the driver side tail light blew out (can't change that until I can open the lift gate). What is going on? What do I do, and where do I start? Obviously all of this stuff is connected, because it all happened at the same time, but I don't understand it. Help!

7 Replies

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

Hello,

Two things could have happened; either some fuses blew when you were connecting the electrical or you have a BCM that is going out. Lets start with the fuses. here is a guide to help us check for power and to see if the fuses are good along with the fuse location and descriptions. Test with the key in the on position.

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

If everything looks okay fuse wise I would think the BCM is out but to be sure. here is a CAN scan which must be done to confirm the issue:

https://youtu.be/InIlnsjOVFA

Here is how you replace the BCM and the unit location below as well. Check out the diagrams (below). Please let us know what you find. We are interested to see what it is.

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Wednesday, July 31st, 2019 AT 12:38 PM

KEVIN BOYCE

MEMBER
4 POSTS

Okay, so I don't know if my last response went through or not, because I don't see it anywhere.
But! I will reiterate what I had planned to say before, below. Anyway, now that I've gone out and checked the fuses. And they are all good, I went a head an bought a test light just to be sure, so when that comes in tomorrow I will look into that again just to make sure I'm not crazy. But thinking about this some more, I had thought maybe it was a faulty relay somewhere. But now I'm thinking that the BCM is probably the issue. Pressing the locks yields a response (not the one we want but.) When I press the locks on the inside, it will click at the BCM and the lights on the dash and the gear shift light up, so there is acknowledgement of the locks being initiated. If I press it on the key-fob, the head lights and tail light blink, so the care acknowledges that as well. If the BCM controls the tail lights (maybe you know this better than I do) then perhaps this is why that left one is out of wack as well (the only thing that worries me here is that the multi-meter detected no power at the tail light socket, however I could have been doing something wrong).
The door sensors must be integrated in the BCM as well, because the dome lights and the radio are in working conditions but they don't respond to the doors being opened. However I can place my hand on the door handle from the outside and the dome lights will come on and the dash lights up, so there is acknowledgement there as well.

I'm ready to buy a BCM! But I'm listening to what you say and trouble shooting first. But thinking ahead, is the BCM in a 2015 Jeep just a plug and play? Disconnect the battery, unplug the ports, disconnect the old BCM, install the new one, plug in the ports, and reconnect the battery? If so, that's easy enough. If it has to be programmed and such. Well where do you get that done at? (Please don't say the dealer)

my previous message asked three questions:

1. Could this be a faulty relay somewhere and do you know if the tail lights are controlled by a relay and which one?
2. (I actually cant remember)
3. The CAN scanner that you referenced in the video was by ALLDATA, but I don't see where you can get the actual handheld device from. Its all just the app. Am I missing something?

This stuff consumes your entire day and brainpower, but I'm motivated to find an answer.
Thanks, in advance!
Added some pictures as well. Why is one upside down. No clue!
1. The tail light out (it's the whole unit!).
2. Touching the door handle lights up the inside of the car.
3. The BCM you know what that looks like.
4. The fuse box.

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Wednesday, July 31st, 2019 AT 8:18 PM

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

Nice work, there are fuses we should check for power before (#14, 10, 12 and 23) we replace the BCM which ties these systems together which you can see from the wiring diagrams below. The BCM must be programmed and is not plug and play like the TIPM is. Check for power and check out the BCM, door lock and blinker wiring diagrams below. Please let us know what you find.

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Thursday, August 1st, 2019 AT 10:18 AM

KEVIN BOYCE

MEMBER
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Okay, well those diagrams made me feel stupid. Because Lord knows I don't understand anything about what they mean! But, here's what I found: I checked on the fuses; now the small fuses light up on both test points, but the fuses that we needed to check are larger 30 and 40amp fuses. Well to you can't check those with a test light (or so I believe) I decided to take those out again, inspect them and then test the prongs that the fuse would sit on. I noticed that one prong lights up, but the other prong doesn't. All of them did that. Now that must be normal because if power was being interrupted then things in the car wouldn't work. (Correct?)
So what I have done now is setup and appointment at a car shop to look at the BCM replacement was quoted at $375.00 on the high end. If it has to be programmed then I might as well let a professional do the whole job yea?
1. Can a test light be placed on an insulated wire? Or does it have to be metal to metal?
This is definitely interesting.

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Thursday, August 1st, 2019 AT 1:20 PM

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

Yes and yes, you can use the test light to probe the wire but use a small amount of silicone sealer to seal the hole after the test. $375.00 sounds about right for the job. Please let me know.