No power to cab

2004 CHEVROLET SILVERADO
195,000 MILES
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WILLIAM WARNER
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My gauges all quit working except speedometer and tachometer. The 4x4 switch won't light up, dome light won't work, windows, door locks, cruise control, A/C, rear defrost all don't work. Took it to a shop to have it scanned and won't communicate with anything. Replaced BCM and no difference. Checked all grounds and cleaned them. Any help would be appreciated.
Feb 12, 2020 at 7:18 AM
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ASEMASTER6371
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Good morning,

Did the shop test for voltage to the fuse block under the hood? It sounds like there is not power coming from the fuse block to the accessories.

Roy
Feb 12, 2020 at 8:34 AM
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WILLIAM WARNER
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There is power everywhere, all fuses are good also.
Feb 12, 2020 at 8:54 AM
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ASEMASTER6371
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When you replaced the BCM, was it new and did you have it flashed to your VIN?

The BCM does control most of those functions.

Beyond that, you have a wiring issue somewhere.

Roy
Feb 12, 2020 at 9:16 AM
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WILLIAM WARNER
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Yes, I had it flashed to my VIN. doesn't make sense of why a scanner can't communicate with anything.
Feb 12, 2020 at 9:18 AM
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ASEMASTER6371
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Was there power to the data link connector? Did the shop verify that?
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Feb 12, 2020 at 9:20 AM
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WILLIAM WARNER
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Yes there is power to it.
Feb 12, 2020 at 9:21 AM
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ASEMASTER6371
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Okay, back to power. Did the shop check for powers to the modules? The ECM would be the first one to check.

Does the check engine light come on with the key in the on position?

I attached the powers and grounds to the ECM to be checked. Check those pins for power and the grounds as well.

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

Roy
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Feb 12, 2020 at 9:30 AM