No power to cab

2004 CHEVROLET SILVERADO
195,000 MILES
Avatar
WILLIAM WARNER
  • MEMBER
  • 4 POSTS
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 11, 2020 at 11:18 PM
Advertisement
Avatar
ASEMASTER6371
  • ✓Experienced Mechanic
  • 52,796 POSTS
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 12:34 AM
Avatar
WILLIAM WARNER
  • MEMBER
  • 4 POSTS
There is power everywhere, all fuses are good also.
Feb 12, 2020 at 12:54 AM
Avatar
ASEMASTER6371
  • ✓Experienced Mechanic
  • 52,796 POSTS
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 1:16 AM
Avatar
WILLIAM WARNER
  • MEMBER
  • 4 POSTS
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 1:18 AM
Avatar
ASEMASTER6371
  • ✓Experienced Mechanic
  • 52,796 POSTS
Was there power to the data link connector? Did the shop verify that?
Images (Click to enlarge)
Professional Diagram for 2CarPros Members
Click here to log in and view diagram.
Professional Diagram for 2CarPros Members
Click here to log in and view diagram.
Feb 12, 2020 at 1:20 AM
Avatar
WILLIAM WARNER
  • MEMBER
  • 4 POSTS
Yes there is power to it.
Feb 12, 2020 at 1:21 AM
Avatar
ASEMASTER6371
  • ✓Experienced Mechanic
  • 52,796 POSTS
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
Images (Click to enlarge)
Professional Diagram for 2CarPros Members
Click here to log in and view diagram.
Professional Diagram for 2CarPros Members
Click here to log in and view diagram.
Professional Diagram for 2CarPros Members
Click here to log in and view diagram.
Feb 12, 2020 at 1:30 AM
Join 2CarPros for free, one of the most advanced car repair communities on the internet. From first-time drivers to seasoned mechanics, everyone is welcome to reply, share details, and get better answers. You can add a temporary image or video first; uploads are limited to 20 MB.
Ask a Free Question
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.