now power when parking. And other problems.

Phantom 4D · August 4, 2023

Pulled out of the carport this morning and the truck shuddered hard and did the same in the driveway. Got out on the road and the transmission shifted hard 1st and 2nd. Low power and the typical noise from the rear. The truck seemed sluggish on the highway and hard the hard downshift coming to a stop. Got to my destination and started to pull into a parking slot while steering left and the truck would hardly move. I straightened the wheel and backed out, no problem. Turned the wheels right, pulled forward and had the same problem. 5 hours later, backing out of the slot, wheels cut right, low power. Pulled forward, wheels cut left, low power. It was as if the truck was being held back. Once on the road, hard downshift at stops. Seemed to be sluggish. I slowed down for some railroad tracks and again, sluggish acceleration. I looked down at the cluster and the 4 wheel hi icon was on. I haven't used 4WD in at least two years. I pulled over, put the truck in park and the parking brake light came on. Mind you, I hadn't noticed the 4WD HI icon earlier. I never use the parking brake either. I hit the switch to turn of the parking brake off and set the transmission to 2WD. The only problem for the rest of the 6 mile drive home still seemed to be sluggish acceleration. Turned into my driveway and hard as I tried, no problems with steering. I put the truck in park, set the parking brake, put the truck in drive and the parking brake went off as it's supposed to do. I've about had it. I only have 26,000 miles on the truck. 2019 Sierra SLT bought new in 2020. I still owe on the loan. Anyone else have similar problems?

silveradosid · August 5, 2023

sounds like your truck is stuck in limp mode, time to get it scanned and find out why

redwngr · August 5, 2023

A bunch of that will have been caused by running with 4wd engaged on dry pavement.

alrockaz · August 5, 2023

Like redwngr said, many of those issues are related being in 4WD. Anything related to difficulty turning, shuddering when turning, etc. are related to the 4WD (lock) issues. The "low power" isn't likely low engine power but the heavy resistance of the transfer case being locked and the front wheels struggling to turn at different speeds on dry pavement. You don't notice it on dirt as one tire is able to slip on dirt (or snow, or mud).

Beyond that, it's speculation for me. Maybe it was on beforehand and you didn't notice, causing damage to the diffs or transfer case. Chunks in the diff can affect acceleration, but it's less about sluggishness and more about a lot of noise and more of a surging as pieces get caught and released. The transfer case could have had something slip and bind up. I would recommend checking/draining those fluids and looking for silvery discoloration.

Your shifting issues of course sound like a classic transmission issue but I could also see how the driveline could create those symptoms. I've blown up a few diffs and transfer cases off road in another vehicle. I've seen the red transfer case fluid come out as Terminator silver before when I completely destroyed a transfer case and drove on it for a while.

None of my speculation covers the parking brake light. And I'm likely hitting a worst case scenario and hopefully it's something much easier and simple. Heck, I would get under the truck and make sure everything looks good. Maybe the a driveshaft is wrapped in 20' of plastic debris, or something wound around an axle and pinched a brake line.

Phantom 4D · August 6, 2023

On 8/5/2023 at 9:57 AM, redwngr said:

A bunch of that will have been caused by running with 4wd engaged on dry pavement.

Agree. I can't figure out why it was in 4WD to start with. I haven't used 4WD in at least two years. Today I took the truck out and did duplicate the problem in 4WD. Going to keep a close eye on it. I haven't located the gremlin who put it in 4WD. Thanks for the replies.