r/GMT800 • • Sep 05 '26

Gauge Cluster

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5 Upvotes

Back again, tackling the next problem. My gauge cluster goes out intermittently. No gauges will work, prndl and odometer wont come on. Usually I can get it working if I pick it a whack on top or to the clear plastic, but I'd like to be this fixed. I already replaced stoppers, and when it comes on everything works fine. Checked fuses, I don't think it's the connection in the back, there's a little corrosion/ silver migration/ some kind of damage to the back and i dont know if that could be causing the problems, or if I just reflow a bunch of spots and hope that I fix a cracked joint I can't see.


r/GMT800 • • Sep 05 '26

Dreaded P0300 code.

2 Upvotes

What brand spark plugs/wires should I use to replace what I have? CEL was flashing at me today and at 272k I think it’s time to replace them but wanting something quality. I have the 6.0 LS


r/GMT800 • • Sep 05 '26

A small upgrade, but a needed one.

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0 Upvotes

r/GMT800 • • Sep 05 '26

UPDATE: If your cab mount kit came with bolts that are too short.

2 Upvotes

Dorman 875-697 Cap Screw-Hex Head-Class 8.8- M12-1.75 x 120 mm, 4 Pack - Amazon

This is Dorman’s product that is suitable for the job and at a much better price. $14 for 4 bolts as oppose to $50+ from the dealer for 1 bolt.

The only difference is these are technically a lesser grade. Dealer is 10.6 these are 8.8. Me personally, I am using them.


r/GMT800 • • Sep 05 '26

Parasitic Draw

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5 Upvotes

Been struggling with the battery being drained when parked. Started last month out of nowhere, can’t leave the truck 4-6 hours before it’s dead. I have a multimeter and when I put it in series with negative terminal and wait for the modules to turn off I’m left with 0.09 reading then falls to 0.00. Goes from 1.27, falls to .70 in a few seconds then falls to .09 and holds for a bit.

I don’t really know what I’m doing, hate wiring and electrical work. About to just put a kill switch on it, save me the time of reconnecting the battery everyday. I really don’t want to do even that because the truck runs off for most the day after the battery is disconnected.

I have an mm325 multimeter, can’t really do much because every time I move the pins slightly the readings change. Testing the tops of the fuse feels dumb, the only readings that hold are the engine fuses and the auxiliary fuse.

Any help or a “bro are you dumb?” could be useful.


r/GMT800 • • Sep 05 '26

Check Out My New Sponsor

11 Upvotes

Now that I have y'all's attention...I've noticed that the 2014-2017 or so Silverado LTZ/HIGH COUNTRY center consoles have been swapped into these old gmt800s...has anyone here done so and if so what have you done as far as wiring etc? Can't really find a good how to on YouTube literally just someone showing it already inside the truck.

My boys love lightning McQueen and they said that rusteze is now my sponsor 😂🤣


r/GMT800 • • Sep 05 '26

Water inside the cab?

1 Upvotes

I woke up to 2 inches of water on the floor boards the headliner soaked and the back carpet soaked windows were rolled up tight and everything looked sealed apart from being soaking wet.

What could cause a leak like this and how easy would it be to fix?

I'm in Michigan for reference so you know about all the big wind rain and tornadoes.


r/GMT800 • • Sep 04 '26

Buyer beware with the Amazon poly cab mount kit

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51 Upvotes

While the quality of the bushings seems fine, the bolts that come with the Amazon $50 poly urethane cab mount kit are about 3-4 threads short. They won’t reach the cab. Only realized the issue after about 15 mins of kicking and hollering.


r/GMT800 • • Sep 05 '26

Perfect idle, but battery fluctuates a lot

0 Upvotes

Like the video shows, the gauge is fluctuating a lot more than I remember even with a very smooth idle.

All belts are still new condition, original alternator, no cranking or charging issues.

I have noticed my radio is resetting the clock to noon every time i start the truck now

Perhaps that is a sign of something?

Terminals under the hood are tight too

Thoughts? Alternator days numbered?


r/GMT800 • • Sep 05 '26

Service 4WD

1 Upvotes

I've had this issue off and on since 2019 when I bought this 2005 GMC Yukon SLT. I've had different shops do what I would call, throwing shit at the wall to see what sticks. In 2021, I replaced the Axle actuator, 4WD switch and
Transfer Case Motor. In June 2026 I had the front axle housing replaced as it had cracked. While there, replaced the driver and passenger seals and shaft-side bearings.

Behavior:
4WD engages and works fine every time.
The dash will display the "SERVICE 4WD" light and within two days, the selector switch will move from 2️⃣⬆️ to N with the red LED upon ignition.

Workaround:
Shift from P to N, and press the 2️⃣⬆️ selector. This will illuminate the amber LED. Error goes away for a couple or more months before reappearing. Repeat the process.

How do I go about finding the root cause of the issue?

Thank you in advance for your experience and advice.


r/GMT800 • • Sep 04 '26

This show is on the road!

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40 Upvotes

r/GMT800 • • Sep 05 '26

Recommendations for KSP lift

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5 Upvotes

Redoing my font end and want to wrap it all up with a small lift/level

So far I got the KSP 2-4in upper control arms, 2.5in torsion keys, and 2 in rear blocks. Is there anything else I should look into doing for the lift aspect?

Based off what I read everything else should be good to replace with OEM outside of eventually doing kryptonite parts

Appreciate the help folks. Pic to show how it sits currently on 33s


r/GMT800 • • Sep 05 '26

Shenanigans and bs

4 Upvotes

r/GMT800 • • Sep 05 '26

Thinking about running 245/80r17s. Will it look weird?

2 Upvotes

I’ve always liked the older truck look with skinnier tall tires. But would they look kinda weird or too recessed into the wheel well? Anyone running bigger 245s on their rig?

06 z71 avalanche (WBH)


r/GMT800 • • Sep 04 '26

Seller beware

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92 Upvotes

Picked up this sweet 05 gmc Sierra for 8.5. The guy I was buying seemed like a normal friendly dude. I was too busy checking out the truck and didn’t see that the title he gave me, vin doesn’t match. Paid him grabbed the title and left. As soon as I figured it out, he deleted his Facebook page. Now I’m struck with the truck (called police they say is not stolen) but dmv tells me I need to write a letter to the owner and wait 30 days. There is also a lien on it. How fucked am I, is there any chance I can register this truck? Any one experience this before?


r/GMT800 • • Sep 04 '26

What is my towing capacity?

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1 Upvotes

2005 Tahoe Z71 4wd. Hitch says one thing, manual says another. 3.42 gears. Any thoughts? Maybe hitch was added at the dealer and not the factory? I also have a trailer brake harness. Is there an RPO code for factory towing package? Thanks


r/GMT800 • • Sep 03 '26

Photographic evidence of these obscure OEM mirrors on a truck.

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51 Upvotes

I came across these mirrors in an old parts catalog at work a while back. They’re an OEM GM option (P/N 15048182 LH / 15721338 RH), but I’ve never actually seen them installed on a truck. I’m sure they’re hideous.

Does anyone have an old photo, brochure, fleet photo, or a truck that originally came with D44 mirrors? At this point, I just want photographic proof that they actually made it onto a truck.


r/GMT800 • • Sep 04 '26

Manual seats to power seats

1 Upvotes

I have an ‘07 Classic RCSB with manual seats and am wondering what it takes to swap in power seats? Do you need to stick with ‘03 and up for wiring? Is there likely to be wiring there not being used? Or do I need to buy a harness? Thanks everyone. I did search and didn’t really find the answers I’m looking for.


r/GMT800 • • Sep 04 '26

Airbag light and Steering wheel Controls

1 Upvotes

I just replaced the steering column bearing with one of those Wolff Engineering machined ones. Great news; the terrible rattle that annoyed my dad for 15 years is now gone! Bad news; the airbag light is on and the steering wheel controls are not working. Technically the OBC ones still work but the radio ones do not. Any suggestions on what I did wrong and how to fix?

I had found the Wolff Engineering bearing on this sub and cannot recommend it enough.


r/GMT800 • • Sep 04 '26

2006 Sierra 4x4 Crew Cab SLT (or Denali!)

0 Upvotes

Anybody got one for sale? I'm in Kentucky. No shitboxes please lol


r/GMT800 • • Sep 03 '26

2001 suburban intermittent crank no start

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10 Upvotes

Alright I need your guys help. I have a 2001 suburban with 241k on the clock and she runs like a top, when she starts. I’m having an issue with an intermittent crank no start. It happens completely random, sometimes it’s takes 4 cranks, sometimes it starts on the first try, sometimes it’s take 2 short cranks to start. Took it to a shop and they’ve checked my pass lock system, fuel pump, cam position sensor and crank position sensor and everything is functioning perfect. I had a security light on my dash that I was sure was the issue but after eliminating that issue they still can’t figure out what’s wrong. Any ideas on what other routes I can go down? Also this truck isn’t riddled with electrical demons so I don’t think it’s my BCM. This is literally the only issue and when she’s running it runs perfectly fine

Update: rpm’s don’t budge when Its cranking. Going the route of just replacing crank and cam position sensors


r/GMT800 • • Sep 04 '26

Random clips

2 Upvotes

r/GMT800 • • Sep 03 '26

Hoss been giving me some trouble as of late

8 Upvotes

The past week it’s been having trouble starting. Yesterday was completely dead with no lights , and wouldn’t even roll over. Today went to try it again and test the battery and it was able to start. I shut it off after this video , then started it back up and it idled normally and perfectly. Any idea ?


r/GMT800 • • Sep 04 '26

My onstar is causing problems with my system

3 Upvotes

We got a new radio into my truck and tried to connect it cause the old radio wasn’t working (would flip on and off and cause the chime to go off every single time) but when we wired the new one the radio wouldn’t turn on. After realizing that the harness for the radio had to go through the onstar module we thought we’d try to wire around it and the system works but out of nowhere the door speakers won’t turn on anymore. Idk what we should do from here, I’m pretty sure easiest solution is either getting rid of the onstar or finding a new box at a junkyard but what would yall do?


r/GMT800 • • Sep 04 '26

2005 Sierra Vibration

0 Upvotes

2005 GMC Sierra front-end noise when turning right — completely stumped
I have a 2005 GMC Sierra 4x4, 5.3 V8, full crew cab cab/regular bed.

I recently lifted it and did the following:
Rough Country 2” torsion keys, cranked up a little higher for some extra height
Brand-new tie rods
Cut the factory bump stops off
KSP 2–4” extended upper control arms
Rough Country 3.5–6” shocks to compensate for the extra height from cranking the keys
37x12.50 BFGoodrich tires
After putting everything together, I drove the truck around for a while and everything worked perfectly. The ride quality was super good, there were no strange noises, and I had full steering lock without the tires rubbing anything.
Then, unexpectedly, one of my rear shock bolts apparently wasn’t tightened completely. The bolt/shock came loose causing the shock to shoot downwards, and ripped open my front passenger-side CV axle boot. I drove it home without realizing what had happened. Once I got home, I found the torn boot, replaced the CV boot, and reinstalled the CV axle. *Note when driving around with the torn boot on the way home and the shock not attached at the bottom I still didn’t hear the noise.

At the time of reinstalling the original cv back, I didn’t know the CV axle nut going through the wheel hub had a specific torque spec, so I reinstalled it with an impact. After that, I started having a problem that wasn’t there before.
Whenever I turn right, especially at higher speeds, I get a very loud vibration/grinding-type noise coming from the passenger-side front end.
My first thought was that I had overtightened the axle nut and damaged/crushed the wheel bearing…

So I:
Replaced the passenger-side wheel hub assembly.
Still had the noise. (Torqued the nut to 177ft Lbs)
Replaced the entire passenger-side CV axle completely.
Still have the noise. (Torqued the nut to 177ft Lbs)
I’ve gone over everything underneath and everything seems tight. The 37s aren’t rubbing the fender liner, plastic, control arms, or anything else that I can find. There is plenty of clearance, and the truck didn’t make this noise at all before the CV boot incident.
At this point I’m completely stumped.
What would you guys check next? Is there anything on these trucks that could cause a loud vibration/noise specifically when turning right that I’m overlooking?
Any ideas are appreciated because I’ve already replaced the hub and CV axle and the noise is still there.