2021 RST with 6.2L charging RV Battery?

[M A D M I K E]

I've just noticed, unlike my 2017 model, my 2021 RST does not charge the RV Trailer Battery when plugged in and the engine running.  That seems unusual to me because all the past models did this automatically - except for my 2003 that I needed to buy an extra fuse for.  Is this the case again?  Did I blow the fuse in spot #63 (TRLR BTRY)?  Do I need an additional fuse or is there something preventing the alternator from directly charging the RV battery?

[EddDe]

Hopefully, a blown fuse. Check this post, it recommends checking Fuse 63, 30 amp is TRLR BATT in the underhood block (same fuse number on my 2020 1500.)
https://www.gm-trucks.com/forums/topic/222819-activating-7-pin-plug-12v-power/

[Anacortes Army Guy]

20 hours ago, M A D M I K E said:

I've just noticed, unlike my 2017 model, my 2021 RST does not charge the RV Trailer Battery when plugged in and the engine running.  That seems unusual to me because all the past models did this automatically - except for my 2003 that I needed to buy an extra fuse for.  Is this the case again?  Did I blow the fuse in spot #63 (TRLR BTRY)?  Do I need an additional fuse or is there something preventing the alternator from directly charging the RV battery?

My 2020 LT charges my RV's battery just fine, so there is definitely something amiss with your setup.  I assume when hooked up all other functions of your seven-pin work (lights, trailer brakes, trailer connected detection system)?  You could check the power to the pin that's suppose to be providing the 12V power to the trailer (pin in the one o'clock position on the male plug I believe??) with a multimeter.

[Z45]

Might need to be in Tow/Haul Mode?

 

Don't know if this is still applicable to current models as this is a few years old info...

Quote

Camper/Trailer Battery Charging Concerns:
Some customers may comment that when towing or hauling a camper/trailer, the auxiliary battery for the camper/trailer will not stay charged. In most cases, this concern is blamed on the new RVC system. While the RVC system does reduce the generator's targeted output voltage to 12.6-13.1 volts when in "Fuel Economy Mode", this feature is bypassed if the tow/haul feature is enabled. With the tow/haul feature enabled, the RVC system will stay in "Charge Mode" and the targeted generator output voltage will be 13.9-15.5 volts, depending on the battery state of charge and the estimated battery temperature. To keep the generator in the "Charge Mode", use either of the following two methods.

• The first method is to use the tow/haul mode when towing or hauling a camper or trailer.

• The second method is to turn on the headlights, which will increase the generator's targeted output voltage to 13.9-14.5 volts.

 

[johnsills1]

On 8/30/2021 at 9:20 AM, M A D M I K E said:

I've just noticed, unlike my 2017 model, my 2021 RST does not charge the RV Trailer Battery when plugged in and the engine running.  That seems unusual to me because all the past models did this automatically - except for my 2003 that I needed to buy an extra fuse for.  Is this the case again?  Did I blow the fuse in spot #63 (TRLR BTRY)?  Do I need an additional fuse or is there something preventing the alternator from directly charging the RV battery?

Not that this is normal, but my truck (2020 6.2 RST) wasn’t charging the battery on my dump trailer. I removed the fuse and saw that it was good. All I can say is that putting the fuse back in fixed the problem. I bought a 7 pin connector tester off of Amazon for 8 bucks. It was delivered the next day, so quick turn around. Now, the pin has power to it continuously, as it should. I know it seems impossible, but I’ve seen crazier ****** having been an electronic technician in the NAVY for 11 years. 90% of electrical problems are cabling. Fuses are considered part of that in my book.