Jay P

The knob above the headlight switch is where you select tow-haul and some other modes. Coming from a diesel truck these trucks don't have any significant grade braking. Also if you put the trans in manual mode and select the highest gear it defeats grade braking no matter what mode you select. Jay

Been that way since they started using independent front suspension. I think 1988 was first year for pickups. Jay

Know someone else with a phone you could try the app on? If you can log into account on computer is has to be an issue with the phone/app combo (something on the phone is corrupt). I have had to wipe/reinstall everything on my iPhone a couple of times for issues like this. Make sure you have a good back up before wiping the phone if you decide to try that. Also look at anything installed on the phone recently. Another app could be causing some conflict with the GMC app. Jay

Can you log into your On Star/My GMC account on a computer? The answer may help lead to the problem. Jay

Is this for the factory Nav? If so you will likely find the disk write protected. Just slide the switch to remove the write protect. Jay

Cutoff for which ones got the new fluid is based on the VIN (should be around March 1st). Dealers should have that info.

Sort of there is an 8L45 and an 8L90 but the Silverado as only had the 8L90. When was your truck built? Starting in March they had the new fluid from the factory and that may be why it doesn't apply. Jay

It's the 8 speed transmissions that are getting new fluid to deal with a shutter issue, not the 6 speed. Hopefully yours is fixed. Jay

Have you tried the new Andriod auto? It's a big improvement. Also the new Apple car play in ios 13 is much better than the old version. I have both an iPhone X and a Galaxy S10E and I like the iPhone/Apple car play better. Open the Android Auto app on your phone. Tap the three line menu icon in the top left corner. Tap Settings. Tap Try the new Android Auto to toggle it on.

It's on the 1st page of this thread.

There are owners of the Colorado/Canyon with the 8 speed that have reported the harsh 1 to 2 shift was fixed with the Blue label MobilOne trans fluid specified in the two TSBs (one TSB for the T1s and one for everything else). Jay

There is an updated fluid for the 8 speed. Seems that the original fluid was absorbing moisture and causing shuttering and some shifting issues. Being a 19 the production date would tell which fluid it had from the factory (I think they switched in March). Here is the TSB -> TSB 18-NA-355. It was updated in July to eliminate the need for testing. Jay

If you want to tow tandem, no way I would do that with any 1500 (brakes). You should be able to stop whatever you are towing going down hill with only the truck brakes (if trailer brakes fail). 2500/3500s are also a lot more stable towing. While a light 5th wheel may seem within the tow limits you will likely exceed the weight carrying capacity of the 1500 due to pin weight. With a 5th wheel you will have around 20% to 25% of the trailer weight on the 5th wheel hitch. You will also need a 6.5' bed to safely tow a 5th wheel. I have popped the rear window out of a truck backing a 5th wheel and it's loud and a mess (thought I could get away without using the slide on the hitch). I just went from a 2500 High Country Diesel to a 1500 Denali because we sold our 5th wheel. You can actually get a better deal on a 3500 SRW that a 2500 with the same trim level. Jay

Normal. It's the A/C pulling moisture out of the air. Jay

The tpms sensor read absolute pressure and the guage reads pressure above atmospheric. Since it looks like you are in Colorado elevation will make it read lower than actual pressure (the higher in elevation the lower the atmospheric pressure). The sensors are inside the tire so no way for them to know outside air pressure. I live at 7000' so mine are off also. Jay