Troubleshooting, Warranty & Recalls Latest Topics

Ac not keeping up

Sun, 21 Jun 2026 12:38:29 +0000

2024 l8t . Ac has never felt really cold even new. But lately it seems a little warmer. When it gets in the upper 80s and a little more humid it just does not keep up. And sometimes at idle it gets warm. My wife's 2008 envoy is better. My son's 2016 is colder. I have an apointment for a third try Monday the 29th at a third dealer to try and get cold ac before my warranty is out. The first two told me something about so many degrees under ambient temp blah blah blah seemed like they didn't want to mess with me. This was set at low. Max air fan speed high. 87 degrees and a little humid.

OEM Trailer Hitch Receiver - Impact tightened by shop

Thu, 18 Jun 2026 13:41:45 +0000

After my recent rear end bumper damage, body shop has made the repairs and included a new OEM receiver hitch. I started thinking about how it was tightened...to specs or by hand or ??. I called the body shop and asked and they said it was tightened by an impact gun. I said I wanted it tightened to OEM specs. They said no problem, bring it to shop today and they will torque to specs, which they say is 74 ft/lbs.

A couple of questions,,,,

1. Should new bolts have been used? If so, how many are there (bill shows one and four (I assume different areas of receiver).

2., Since they torqued with impact gun and now are going to probably loosen and then torque to spces, will that damage/stretch the bolts?

3. If old bolts were reused (truck has 9000 miles), is that a problem?

4. Any other things iI may have missed with regard to receiver replacement?

NOTE: Attached are the receiver hitch specs from my digital OEM service manual. It shows to horizontal mounting bolts and four vertically mounted bolts. Other sections of manual reference eight vertical bolts.

Thanks!

DTC P2C48 auxiliary cooling pump

Sat, 13 Jun 2026 17:26:54 +0000

Hello, Im in a bit of a bind maybe someone could help me out.

We towed our trailer, up a pretty steep incline (395 north of Bishop) done it before no issues. I got to our campground turn truck off, i restarted the truck about an hour later and check engine light turns on. Found DTC P2C48, unable to reset. This morning i removed the plug, there's 12.12v at the plug. Reservoir near firewall is full of coolant, checked for leaks nothing. I dont hear or feel the pump turning on. My dilemma, is nearest dealer is 4hrs away that has the pump instock.

Is it safe to drive?

By me checking the available voltage at the connector and not hearing/feeling pump turn on, is it a bad pump?

Please help...

Damaged Left Rear Bumper & Left Rear Quarter Panel - Repair Questions

Mon, 25 May 2026 02:28:35 +0000

Parking Lot Damage...

The bumper appears to be pushed forward into the body and scratched the body behind the bumper.

The left side fender near left edge of bumper, where bumper wraps forward, appears bulged out.

The very bottom lower left of tailgate now scrapes against body when opening the tailgate.

NOTE: Interesting....the chrome bumper does not appear scratched nor the plastic trim (pic of bumper with black marks is camera/light reflection.

Repair questions…

1. Will the complete truck bed need to be replaced due the bulging out of fender and bed/fender pushed slightly inward causing tailgate to run?

2. If no bed is not replaced. How do they address the bulging outward and tailgate rub?

3. Other thoughts on this repair?

Thanks?

Recalls 2024 Chevrolet HD

Sat, 01 Nov 2025 20:37:50 +0000

Truck is 2025 Chevrolet 2500 HD Custom 6.6 Gas . Truck was built in Oshawa .

I have a couple of threads on here fellas but I thought I would just check something out .

Someone has told me that there is a recall or a special bulletin for the tranny on this truck . Is this true ?

Also where do I look for recalls and Special Bulletins for this truck ?

Thank You !

Electrical problem

Fri, 05 Jun 2026 15:58:01 +0000

installed a set of OEM mirrors that had puddles and power folding with the goal of adding the options to a switch panel to control since the truck did not come with the features.
after hooking everything up my head lights don not come on and interior lights are flashing along with hyper flash signal lights.
I took the mirrors off and installed the factory ones and no fix.
Disconnected battery and tried to rest the BCM with no luck.
Along with the interlock solenoid clicking when I press the brake to put in gear.
Truck runs and drives fine.

Cracked tailgate touch pad replacement?

Sat, 21 Feb 2026 19:19:45 +0000

My 2021 2500 HD has a crack in the exterior tailgate touch pad that opens/closes the tailgate. (see the pic) I use this switch often. It's exposed to the weather, so I'd like to replace this insert plastic cover to keep out the rain. (FYI, the truck has about 40k miles and is mostly garaged. I'm surprised that this item would crack after about 5 years of service.) Does anyone have the part # and a source for me to obtain a replacement? Thx!

Keyless touch pad on door

Mon, 25 May 2026 20:36:15 +0000

I have a 2023 Chevy 2500HD Custom, i had Service Chevy in Lafayette, LA try to installed the wireless keypad on my truck(like the ford truck and SUVs have). They are having trouble getting it to sync with my truck. Has anyone else installed this item with success? because they can’t find seem to get any help resolving the issue.

Those with a '23 2500/3500HD - Can you verify a body part for me?

Sat, 30 May 2026 13:29:18 +0000

I took my truck in for a left side bumper/tailgate/fender repair estimate.

There is a section of the tailgate jamb that I was hoping someone could verify and send me a pic of theirs.

I have attached two pics...left and right sides of tailgate jamb. Red markings indicate areas I am referring to on damaged side. Green marking indicate left side where no damage occured.

The sheet metal edge that is spot welded and two black screws on each side is where I am focusing. The left side sheet metal vertical section along the edge has almost no gap and the lower black screw looks more forward (compared to right side).

Can someone who has a 2023 2500/3500 snap a couple of pics of this same door jamb section on both the left and right side and post and/or send to me. It would be much appreciated.

Thanks!

AC 3-10min Delay on cold start - NIGHTMARE ISSUES!!! (2020-2023 trucks)

Tue, 19 May 2026 16:23:31 +0000

Update (see below for my original post) - Alright so the pressure switch and low freon fix both helped the issue, but very quickly the AC started the delay issue again. Ugh. So I took the truck to a HD truck repair place about 5min from me, these guys are awesome, all they work on is HD trucks so I trust them more than the dealer.

NOTE - Already did the pressure sensor and found the low freon issue and added freon before this.

Day 1 - diag'd as a bad control assembly (dash knobs), they said it's common and they do those often. $800 qoute, 2-3 hours should be back up and running quick, part took 3 days to arrive.

Day 4 - These guys actually tested the truck out in the heat, I don't mind the extra testing, that way they actually figure it out. Well low and behold, now it's the expansion valve, ok cool, they give me discount and said it will be ready pretty quick, but of course they test it in the heat hard before letting me pickup the truck. Qoute is now $1100. ($300 more for the expansion valve isn't bad)

Day 6 - Nope, bad news again, issue is still there. But good news, is an electrical issue with the compressor. Compressor can get the vent temps to 42f no problem, but at idle or cold start it quits. Now they are doing the compressor. I was pretty sure based on what I've read on forums and FB that the compressor had some issues in these trucks and the new versions fixed this.

Day 8 - Finally fixed, total cost for everything was now $1888, they ate a ton of the labor thankfully. Honestly cheaper than I had thought, I thought it would be just the compressor and I expected $2000ish.

Original post below

So my truck had low freon from factory, easy fix myself, but I had this really weird delay when starting the truck that started right after that, the AC would blow hot for 3-10min every time, then go cold BUT stay cold as long as it stayed running. No codes, nothing. GMC couldn't figure it out, and just said replace the compressor but I found a post on FB were a guy said both of his GMCs AC died at 50k miles and the GMC dealer replaced a "sensor". Huh, ok, that sounds easy, now the pressure sensor for these trucks is right by the compressor, not easy to get to(or even find at all!), but also still a 5min job. The part is hard to find, my dealer said is was not even available, however Rock Auto had them HERE for $26 bucks shipped. Its a 5min job, but you must do a full reset of the AC system, pull the battery for 3 min and its good to go.

I did a complete video guide but I won't link it so as not to break any rules here.

A/C issue

Sat, 04 Apr 2026 17:30:45 +0000

I have a 2024HD L5P. I have it to 2 different dealers a total of 3 times. The problem is when you get in the truck and lets say it is 90 degrees in the truck the A/C will not go into full blast. It is set on auto at 71 degrees. This is an intermittent problem and of course the dealer can't duplicate it. I opened a case with GM last fall, Has anyone run into this problem?

2021 3500 CCLB LTZ tailgate stuck

Sat, 02 May 2026 20:28:37 +0000

Hello: yesterday I pushed the button on the tailgate to close it. It went to what I would describe as the "first" latched position and stopped. It isn't completely closed but is latched and won't open or finish closing. When I press the button, I hear a noise from inside the tailgate, but it isn't the sound of the motor trying to pull the tailgate closed, or the click of the latch releasing. Double clicking the tailgate open icon on the remote gives the effect of it trying to work. The owner's manual says: the electric tailgate can be opened if the battery is dead: "contact the dealer".
The battery isn't dead. Since it has power, I'm curious if anyone else has experienced this problem. This is my 14th GM truck but first with the electric tailgate. As a retired automotive tech, I'd like to fix it myself if possible.
I have looked down from the top of the tailgate edges to see if anything is jammed in latches. I have removed the inner access cover and found the latch release pins.

When I double click the fob, they rotate. I have attached cable ties (see photo) to these and pulled both of them at the same time, no success.

Anyone have any experience with this?

Thanks, JC

2020 Silverado 3500HD Duramax Diesel "Allison" transmission rear wheel lock-up lawsuit

Tue, 28 Apr 2026 19:00:22 +0000

Rear wheels lock up when it tries to downshift while towing (going uphill with our 5th-wheel RV). This is the known problem that 463,000 trucks were recalled and programed to try and let the owner know about 10,000 miles before a lock-up happens (feels like you ran over a telephone pole). Ours just happens to be one of the "lucky" ones that locks up without prior warning. We took it into nearest Chevy dealer (out in CA). After 2 weeks waiting, we were told by the dealer they didn't need to do anything relating to the recall because it wasn't throwing the PO747 error code. I offered to take a technician up a hill on the highway with our 13,000 lbs 5th-wheel in tow, but they declined. They asked us to wait in California (2100 miles from our home) for another 8 weeks for a GM engineer to come to the dealership and look at it. We declined and put our camper in storage and drove the truck home to be serviced local. We can't wait the 8-10 weeks for a GM engineer. Does anyone know who to contact at GM to get our costs covered? (note: We have filed reports with NHTSA and opened a file with the GM Customer Care line- Who told us we were covered by the recall, but because they were not part of the GM technical service (TAC), they had no authorization to tell the dealer what to do as dealers are independently owned.) Are we forced into a lawsuit to recover our repair costs and expenses for what should be a warranty repair?

And imagine our surprise when we learned that despite the branding on the hood, we didn't have an Allison transmission.

Reference: Special Coverage N242454441-03

2020 3500HD - dead fuel pump module

Tue, 30 Dec 2025 21:29:51 +0000

2020 3500HD 6.6 gas with about 69,000 mi.

I had a crank no start a month ago and then just recently truck had trouble starting and would die on the road. Code P129F and my best guess is I have the fuel pump control module failure.

GM only recalled certain vehicles so I guess mine is on me for now.

Internet advice tells me these have to be reprogrammed at the dealer. Some people report they have swapped it and it runs fine.

Whats the official verdict? Can I replace this myself or am I stuck using the dealer? It looks like its relatively easy to replace.

Help replacing brakes on the 2020+ models

Wed, 15 Apr 2026 19:15:29 +0000

So I am seeing a ton of conflicting info on doing the brakes on these trucks, anyone have a complete step by step from GM? I've heard you need to use brake service mode, but I've also heard you only need to do that on the 1500s. And do you need remove some brake fluid before compressing the pistons for the new pads? Also do you have to run the brake life sensors or can those be left off?

Any clear help would be awesome! I've got the new pads but don't want to mess anything up here.

Should I buy a bi-directional scan tool? (plus J2534 and TDS)

Mon, 02 Feb 2026 18:48:34 +0000

I have always maximized my DIY. tTat is getting hard to do as technology increases. Below is a list of things I want to do to my 2020 Silverado 2500HD L5P Duramax High Country trim:

1) Replace the missing Communications Interface module (Wifi) located above the gas pedal. This also does wireless carplay and bluetooth.

2) I have a "Service Forward Camera" error that requires a Forward Camera Learn procedure at a minimum, but could be a rabbit hole of issues. It worked a few months ago.

3) Reduce the TPMS threshold warning pressure. There are dedicated boxes for this, I think, but not worth it as a stand alone 1-time use for me.

4) KeyFob programming w/ push button start. I only have a single keyfob and it is programmed as driver #3. I need to add a keyfob and would like to update the Driver #, but don't have to.

5) Speedometer calibration for larger tires that are 285/65R20. I think this requires HP Tuners and a ECU license there too.

My question is, do I bite the bullet of the upfront cost of equipment because it should save me money in the long run? The costs I have found are:

J2534 boxes:
MDI2 ($1,300)

If you know if an off-brand one that works well, please do share

Bi-directional scan tools:
Autel MK900-BT ($600)
Thinkcar 689BT ($600)
Snap-on ModisUltra ($1,400)

TDS license through AC Delco for Body module license
$50 per vehicle license and lasts 2 years

I do have an OBDLink MX+ ($150) that can be used as a passthrough device as bluetooth. At least I think it can.

Any info' you could toss my way is much appreciated. I'm not scared of the work, just the cost concern of buying cheap and buying twice. I'm more harbor freight than snap-on. The irony is not lost on my that I drive a high country and am frugal.

Radio Update

Mon, 30 Mar 2026 15:15:43 +0000

I have a 2025 GMC Denali 2500hd Duramax. I took the truck in for the radio update and now Android Auto will not connect to my phone (Android) all the time ( pixel 8 with all the updates).

I took it back to the dealer and they reinstalled the info system and still doing the same thing. I have done all the changes on my phone that I have found on the internet with no luck. It worked fine before the update, any ideas?

Rear Window Leak and GM warranty warning

Fri, 18 Mar 2022 15:21:34 +0000

The rear sliding glass window of my 2020 GMC Sierra 2500 developed a leak in January of 2021. It caused water to saturate the carpet under the rear seats and allowed water to enter the rear seatback storage compartments. TSB 18-NA-383 states the cause is from cracks developing in the rear sliding window plastic upper rail glass guide and the solution instructs dealers to put seam sealant over the cracks. Skip forward a year later and 3,000 miles out of factory warranty. The sealant failed and the window was leaking again. GM initially refused to pay anything and the dealer wanted $1,382.70 because they stated I needed a full rear window replacement. Extended warranty wouldn't cover it because it was not a mechanical breakdown. After a many calls to GM customer assistance, they agreed to cover 70% leaving me to still pay $414. This window leak is not isolated to just a few. I had a 2019 GMC Sierra 1500 in which the rear window leaked before I traded. A friend of mine has a 2020 GMC Sierra 2500 and his window is leaking. There are hundreds of pages of forums in the 1500 forums regarding a leaking rear window.

GM will try to put a bandage on the window cracks in the form of sealant instead of actually replacing the defective window. Many of the people in the forums report that the sealant does not last as was the case with mine. If you are unlucky enough to fall outside of warranty when the sealant fails, GM will not cover anything without a fight.

Hose leak... transmission cooler hose???

Tue, 03 Mar 2026 02:11:46 +0000

Purchased a "CPO" 2022 GMC Sierra 2500HD recently and am slowly learning the ins and outs of the truck. I found what appears to be a leaking hose covered in dirt/sludge. It is on the passenger side and routes under the radiator. I am assuming this is a transmission cooler hose but am not certain. Picture attached for reference. If it is a transmission cooler hose leaking, is this covered under the GM powertrain or bumper-to-bumper warranty?

Rear leaf spring clunk gone with TSB 21-na-138 fix

Mon, 03 Jun 2024 21:51:53 +0000

So I had the inserts done under warranty today and so far so good. No clunking at all anymore. Hopefully that remains the case.
it feels a hair stiffer now in the back but that’s probably just my mind.

I’m happy with the fix so far.

2021 2500HD A/C stops blowing cold at highway speeds

Sun, 07 Jul 2024 20:42:29 +0000

I have a 2021 GMC 2500HD Denali that stops blowing cold when reaching highway speeds. When first start it and idling, it will blow cold. Usually as long as staying within the neighborhood, it will blow cold; however, once get onto the highway and over 55, it stops blowing cold. I can put the truck into neutral to coast on the highway, and the A/C will usually begin blowing cold again. However, compressor shuts off once I put it back into drive. I have had the vehicle at the dealership 3 times over for the past 3 weeks with this issue. First visit (6/17/2024), they reprogrammed the computer (not covered by warranty, so $630 bill), and I was able to pick it up at the end of the day on Friday, 6/21. Second visit (6/24/2024), they replaced the compressor ($1600 bill as "only partially covered by warranty") Picked it up on the Wednesday, the26th, but wasn't able to take a highway trip until Saturday, 6/29 where I still experienced the issue. Third visit (dropped off on 7/1), they called me to say they had no clue as "computer shows no issues" but I needed to come in to disconnect my Banks Derringer as they "were certain" that was the issue. They "drove it a few miles" afterwards and said the Derringer was the issue all along as "the A/C worked like it was supposed to." I picked the vehicle up on 7/2 and left town on a road trip on 7/3. As soon as I hit highway speeds (Derringer still unplugged to prove that was not the issue), the A/C stopped blowing cold yet again. Further info., the technician/dealership has not yet opened a TAC case - unofficially due to the technician's ego.

Anyone have any ideas/advice as the dealership cannot seem to properly diagnose the issue. I have another non-refundable camping trip this coming weekend, so I need to get this issue resolved... Thanks!

Trailer Light Control

Mon, 16 Mar 2026 19:35:42 +0000

I drive a 2021 Chevy 2500hd. Having an issue with trailer lights staying on. Is there a trailer light control module on my truck? The dealership is telling me no. But everything else I see online it says there is one. Does anyone know which module controls the trailer lights on this truck? Vin 1GB1YLE73MF171983

Infotainment audio cuts out.

Fri, 13 Mar 2026 14:09:33 +0000

So does anyone have a sloution to the infotainment losing audio upon startup? Mine cuts out for a second (does it 8-10 times) after starting the truck. My buddy's does the same. I have had a software update done at the dealer and it actually seems worse after that.

Codes will not clear after changing batteries

Sat, 21 Feb 2026 14:55:58 +0000

During the cold freeze a few weeks ago, fuel gelled truck would not start, to many attempts to start cause battery low voltage. Vehicle towed to heated garage on battery charger. Trucks starts after thawed, but a cluster of engine lights were on, ABS, check engine, traction control, engine power reduced, check trailer brake. New acdelco batteries installed, lights remained on. Scanned and tried to clear codes, codes will not clear. Changed fuel filter, will not allow to reset fuel filter.

tried removing negatives from both batteries and followed steps for hard reset. Lights remain on. Thank you for any help.

2025 GMC 2500 Front Axle seals leaking

Mon, 09 Mar 2026 23:03:37 +0000

Is anyone else having trouble with the front axle seals leaking? My truck started leaking at just 1600mi. It took two months to get a warranty appointment but eventually they replaced the seal. Now less than a month and 200 miles later and its leaking again. When I contacted the dealership, they said every 2500 in town is leaking because of the cold weather and they needed to order parts.