2010 KW possible bad cecu

[Bigmack713]

Hello all, I recently lost my turn signals headlights and washer functions. I've read some threads and have checked fuses and relays. Also checked power and ground to the cecu under the cup holder. All seems to be fine. This truck has always had issues what speedometer and tachometer not working. But I fear that the cecu might have gone bad altogether. Is there any other test to conduct to completely eliminate other issues before I purchase a new cecu? I heard about a chassis node, but I cannot find it. Please advise. Thank you in advance[/size][/font]