2020 Silverado 1500 LT 5.3L Electronic Problems

[D Farrow]

2020 Silverado purchased used April last year. Everything worked as expected until December (in Michigan) when fobs stopped working intermittently. Vehicle starts and runs normally when fob is in pocket. Fob batteries tested good but were replaced with new. Mechanic friend suggested battery load test (Michigan winter is the time most of my batteries have failed in the past). Load test revealed failed battery (factory original). Battery replaced and all problems resolved until about one month ago when fobs would fail intermittently as with problem last winter. Battery tested good. Fob batteries tested good. Noted low voltage on DIC voltmeter. Alternator tested bad. Alternator replaced with satisfactory charging now showing on DIC. Fob issues persisted for about 3 days then suddenly disappeared. About one week later fob issues returned and "Service Tire Pressure Monitoring System" displayed on the DIC which would then vanish. TPMS is working as it should when no alert displayed. With fob in pocket the truck starts, runs, and all electrical functions are normal. Pulling battery terminals and shorting together for residual voltage drain was performed too. Intermittent "No Remote Detected" displays on DIC when starting with fob in pocket. 
Any suggestions will be greatly appreciated.

[newdude]

20 minutes ago, D Farrow said:

2020 Silverado purchased used April last year. Everything worked as expected until December (in Michigan) when fobs stopped working intermittently. Vehicle starts and runs normally when fob is in pocket. Fob batteries tested good but were replaced with new. Mechanic friend suggested battery load test (Michigan winter is the time most of my batteries have failed in the past). Load test revealed failed battery (factory original). Battery replaced and all problems resolved until about one month ago when fobs would fail intermittently as with problem last winter. Battery tested good. Fob batteries tested good. Noted low voltage on DIC voltmeter. Alternator tested bad. Alternator replaced with satisfactory charging now showing on DIC. Fob issues persisted for about 3 days then suddenly disappeared. About one week later fob issues returned and "Service Tire Pressure Monitoring System" displayed on the DIC which would then vanish. TPMS is working as it should when no alert displayed. With fob in pocket the truck starts, runs, and all electrical functions are normal. Pulling battery terminals and shorting together for residual voltage drain was performed too. Intermittent "No Remote Detected" displays on DIC when starting with fob in pocket. 
Any suggestions will be greatly appreciated.

 

 

Sounds like a fault with the remote control door lock receiver or in the wiring circuits to it.  

[D Farrow]

I have been trying to figure out how to troubleshoot the remote receiver and associated wiring...

[davester]

alldata.com for wiring diagrams, connector pinouts, diagnostic procedures

a more advanced code reader that can access all the computers in your truck, including the rdclr.  Not cheap. a good j2534 obdii-usb passthrough device, a windows laptop and finding GDS2 software on the internet would probably be the cheapest way

[silveradosid]

don't know what it cost in the usa but in canada 30 bucks gives you 3 day of access to gm service information for everything on your truck