No crank no start, no ground to 3 fuses?

Tiny
DAVO23
  • MEMBER
  • 2019 CHEVROLET SILVERADO
  • 6.2L
  • V8
  • 4WD
  • AUTOMATIC
  • 74,000 MILES
Hello to all! I'm looking for help/ good wiring diagram for my truck. It stalled at idle the other day and now no crank no start. The only code I get from scanning is U0100 (lost communication with ECM). I have three fuses under the hood with no solid ground reading. The three fuses are highlighted in pic below. A video testing for ground is in the video. Thanks to all for any advice or help at all!
Image & Video (Click to make bigger)
Thumb
Thumb
Saturday, March 8th, 2025 AT 8:56 AM

6 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 50,314 POSTS
I am not sure what you are talking about the fuse grounding? does the fuse have power on both sides? I saw the video, but I am not sure what the tester you are using is saying? Here are the fuse that run the PCM. Please go over them and get back to me.

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

Check out the images (below).
Image (Click to make bigger)
Thumb
Was this
answer
helpful?
Yes
No
Saturday, March 8th, 2025 AT 12:46 PM
Tiny
DAVO23
  • MEMBER
  • 3 POSTS
Thank you, Ken for the wiring schematic. My scanner showed “ lost communication with ECM” after the stalling and no crank no start issue, I ordered a new ECM and plan to have it programmed after I receive and install it. I have key voltage to both sides of all fuses related. The crank/ start relay = good... In the video I hook my test light to the battery positive and went through the fuses checking for ground... All were showing a ground in the fuse box. (Steady light) except those three fuses which was a blinking light. I just thought that maybe I might have a bad ground somewhere in the system or broken wire.
Thank you, Ken.
Was this
answer
helpful?
Yes
No
Saturday, March 8th, 2025 AT 1:50 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 50,314 POSTS
I see, I am wondering if the tester is seeing low voltage or no voltage? Can I ask which fuses gave you the bad test? It does sound like the PCM is bad, here is how to change it out. Once the electrical connectors are removed check them for corrosion. Check out the images (below). Let us know how it goes.
Images (Click to make bigger)
Thumb
Thumb
Thumb
Thumb
Thumb
Was this
answer
helpful?
Yes
No
+1
Monday, March 10th, 2025 AT 8:49 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 50,314 POSTS
Also, you will need to remove the inner fender liner on the driver side front.
Was this
answer
helpful?
Yes
No
Monday, March 10th, 2025 AT 8:54 AM
Tiny
DAVO23
  • MEMBER
  • 3 POSTS
The three fuses that weren't showing a solid ground were the highlighted ones in the attached photo. I have removed the PCM and installed a new one and am going to haul it to a dealership to have it programmed later this week. Hopefully this fixes the issue.

Thank you, Ken!
Image (Click to make bigger)
Thumb
Was this
answer
helpful?
Yes
No
Monday, March 10th, 2025 AT 10:22 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 50,314 POSTS
Yep, all we can do, please let me know what happens, have a good week ;)
Was this
answer
helpful?
Yes
No
Tuesday, March 11th, 2025 AT 9:55 AM

Please login or register to post a reply.

Related Engine Not Cranking Over Content

Car Not Cranking? Try This | EASY
VIDEO
Car Not Cranking? Try This | EASY
In­struc­tional re­pair video
Starter Not Working
GUIDE
Starter Not Working
This guide is de­signed to help you iden­tify whether the is­sue with your non-work­ing starter mo­tor is due to an elec­tri­cal prob­lem or a fault within the starter mo­tor it­self...
VIEW MORE