Probs Body Control Module (Intermittent)

[hflores3]

Would appreciate your help guys.
a) Code found - U0140-00 ... no communication with Body Control Module
b) Car goes into limp home
c) Does anyone have a graphic on where all the "ground points" are (as a diagnostic starting point)? ...that they could share?
d) I need to check the BCM connection - perhaps clean and use some dialectic grease on it as well.

I regret not purchasing a service manual. I may need to now. ....but in the meantime - would you gents throw me a bone?

Henry

[STL_G8GT]

I don't believe I have a diagram of all of the grounds. I have one that lists them, but not with a corresponding picture.

[STL_G8GT]

G110 is MAF, ECM, even ign coils. I think that one is the engine block, which is then jumpered to the frame at the front left to the abs bracket.
G201 is BCM, Airbags, Sunroof, all sorts of stuff. It's most likely the ground under the dash to the left looking at the steering wheel.

Is the code pending, history, or current?

[Napalm]

Check the fuses for comm enable, ecu, tcu, under the hood

check the fuses for security, IP, and I suspect there's another one related to controls.

Those all interplay with the BCM.

There there are some relays and one is even labeled communications - I think it's an interior relay. It might have gone bad or weakly contacts. Hard to say.

Then I would check battery voltage, and if the car cranks - I'd check voltage at the battery with the car running just to make sure it's up over 12. you should get a alternator light if it wasn't but doesn't mean there aren't other issues.

[hflores3]

If you guys were near - I would buy each you beer and fajitas!

Thanks for the leads!

Will chase this tonight!


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[hflores3]

If you have a “list” of ground points you can share — “mucho appreciado!”




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[STL_G8GT]

If you have a “list” of ground points you can share — “mucho appreciado!”




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The list I have is about fifteen ground points, and then each one you can click on and it shows the circuits it impacts, but not the location. It wouldn't do much good visually. The two I referenced are the ones that would impact the bcm and ecm. It's possible that another module lost contact with the bcm, not the bcm losing its ground, if that makes sense. In that case, though, I'd imagine other codes would be tripped.

Again - is the code pending, current, or history? Is it an intermittent thing? When you shut off and restart is the car fine?

[Napalm]

Did this happen on a start up? get the X contact dealer , check for code, no - comms code. shut down. Restart - still X car in limp home mode.

Then second or third start up - acts fine but the code lingers in history till cleared?

2 things - my car did something similar but I don't have the code number a few years ago - about 2 weeks before my battery died. Checked the systems, new battery - hasn't happened since.

So it's possible you had a low volt situation during the start up check sum and one of the modules didn't communicate with the BCM in time sequence.

This is why I suggest you check those fuses too. If it continues - and check your battery voltages.

[hflores3]

Did “not” happen during start up.

I did “indeed” get the “contact dealer” message.

I may run to AutoZone for a code read (my code reader was a Hurricane Harvey” casualty).

I’ve got another on the way.


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[hflores3]

Battery is less than 3 months old.


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[-Ray-]

Did Harvey pee on your BCM Henry?

I think you are looking at a replacement. ACDELCO 22860591 from Rock auto is $150.00