21 GMC Sierra AT4 1500 Mirrors

[David Krueger]

 First off, I am not happy with the mirrors on my 21 GMC sierra 1500. I hate "objects in mirror appear closer than they are"  Who ever thought, that this would be a good idea to put on a truck used for pulling trailers.  Absolutely can't judge distance when backing up. Next, what engineer thought that it would be a good idea to put the convex mirror on the drivers side, in the upper left corner of the mirror. The Mirrors are to small to begin with. Lets make them worse by putting the convex mirror in a stupid place. It belongs on the bottom.

 I'm thinking about replacing the mirrors with mirrors from a HD. They are available from salvage yards. I have a few questions about this before I start buying mirrors. I have a 2021 AT4 with a 3.0 diesel. About 36k miles. Love the truck. I am wondering if I go to the larger mirror, will it affect my fuel mileage? Will they bolt up to my truck? My truck has power folding mirrors, lights on the front side, and auto dim on the DS only. 

 I was thinking about getting mirrors from a HD Denali . They have cameras in them, can my truck be programed to use the cameras? Will they fit on my truck?

 Has anyone else tryed this swap? Any advice would greatly apreciated.

[newdude]

2 hours ago, David Krueger said:

 First off, I am not happy with the mirrors on my 21 GMC sierra 1500. I hate "objects in mirror appear closer than they are"  Who ever thought, that this would be a good idea to put on a truck used for pulling trailers.  Absolutely can't judge distance when backing up. Next, what engineer thought that it would be a good idea to put the convex mirror on the drivers side, in the upper left corner of the mirror. The Mirrors are to small to begin with. Lets make them worse by putting the convex mirror in a stupid place. It belongs on the bottom.

 I'm thinking about replacing the mirrors with mirrors from a HD. They are available from salvage yards. I have a few questions about this before I start buying mirrors. I have a 2021 AT4 with a 3.0 diesel. About 36k miles. Love the truck. I am wondering if I go to the larger mirror, will it affect my fuel mileage? Will they bolt up to my truck? My truck has power folding mirrors, lights on the front side, and auto dim on the DS only. 

 I was thinking about getting mirrors from a HD Denali . They have cameras in them, can my truck be programed to use the cameras? Will they fit on my truck?

 Has anyone else tryed this swap? Any advice would greatly apreciated.

 

 

 

HD tow mirrors will not fit the 1500s.  The doors are different between the two as is the mirror mount design and stud pattern.  

 

You will need the 1500 loaded tow mirrors from a GMC (because the doors are also different 1500 Chevy vs GMC), option code is DQS from GM, or, use the ones from Boost Auto Parts.  Only problem with Boost is they are at a fixed 1/2 extension position where the OEM ones have the 3 or so inches of extension travel.  

Edited July 26, 2024 by newdude

[David Krueger]

Thank You, That helps alot. I'll see if any salvage yards have them. If not, I'll price them out. 

[redwngr]

T1 1500's have factory tow mirrors available.  1500's were revised before the HD's and the T1 1500's didn't get tow mirrors until HD's platform was revised

 

21 LM2 and 23 LZO 1500 Denali's

Both 4wd, both standard box and on 20's 

Ordered the 21 with tow mirrors and sunroof.   

Ordered the 23 with regular mirrors and no sunroof. 

Both trucks have the full camera stuff in the mirrors

Bed cover was moved from the 21 to the 23. 

 

Both trucks doing/did the same jobs

36000+/- miles on the LM2

19000 so far on the LZO 

 

 

I log all fuel and do hand calcs to compare with the trucks tripmeter numbers.

 

The 21 got 26. something over it's lifetime

The 23 is running 29.6 so far. 

 

I don't know how much of the mpg difference is due to the mirrors.

Speculation when LZO came out was that it might get slightly lower mpg.  (because it has a higher output levels)

That has not be the experience with these 2 trucks. 

 

[David Krueger]

14 hours ago, redwngr said:

T1 1500's have factory tow mirrors available.  1500's were revised before the HD's and the T1 1500's didn't get tow mirrors until HD's platform was revised

 

21 LM2 and 23 LZO 1500 Denali's

Both 4wd, both standard box and on 20's 

Ordered the 21 with tow mirrors and sunroof.   

Ordered the 23 with regular mirrors and no sunroof. 

Both trucks have the full camera stuff in the mirrors

Bed cover was moved from the 21 to the 23. 

 

Both trucks doing/did the same jobs

36000+/- miles on the LM2

19000 so far on the LZO 

 

 

I log all fuel and do hand calcs to compare with the trucks tripmeter numbers.

 

The 21 got 26. something over it's lifetime

The 23 is running 29.6 so far. 

 

I don't know how much of the mpg difference is due to the mirrors.

Speculation when LZO came out was that it might get slightly lower mpg.  (because it has a higher output levels)

That has not be the experience with these 2 trucks. 

 

 I found a set of Mirrors, Ineed to check to make sure that they will fit my truck before I buy them. DS 84994407 and PS 84994408. The discription says that they will fit the Sierra and/or the Silverado, I don't know if that's true. I will also need to get a wire harness for them from what I can tell. I haven't found that yet. 

  Thanks for the picture. I can do a good compairison with it. 

 So what do you think of the small mirrors verses the tow mirrors? Are the tow mirrors noisey?

I am retired, 67 yrs. old. I figure that this should be my last truck. I think that I should be comfortable with it, so better mirrors. On the other hand I don't want to spend a bunch of money on them and then find out that I don't like them. 

 I have 10 ft wide garage doors so they should fit through it no problem.

[redwngr]

1 hour ago, David Krueger said:

 I found a set of Mirrors, Ineed to check to make sure that they will fit my truck before I buy them. DS 84994407 and PS 84994408. The discription says that they will fit the Sierra and/or the Silverado, I don't know if that's true. I will also need to get a wire harness for them from what I can tell. I haven't found that yet. 

  Thanks for the picture. I can do a good compairison with it. 

 So what do you think of the small mirrors verses the tow mirrors? Are the tow mirrors noisey?

I am retired, 67 yrs. old. I figure that this should be my last truck. I think that I should be comfortable with it, so better mirrors. On the other hand I don't want to spend a bunch of money on them and then find out that I don't like them. 

 I have 10 ft wide garage doors so they should fit through it no problem.

 

 

 

I can't help with the part numbers.

You could get a quote for 'price and availability' from a dealer parts department or from one of the online GM parts suppliers.   Parts department will have part numbers on the quote. 

 

I have been a long time GM trailering mirror fan. 

To make a long story short, I found (on a '21 1500) that the blind spot on passenger side when checking to the right at intersections was worse than with previous generations of cab/tow mirror. 

I didn't notice them being noisy. 

 

I factory ordered them on the  '21.

They were power fold.

 

As pictured, I ordered the  '23 without tow mirrors. 

The '23, doing same tasks, is getting better mpg as the '21. 

 

For my use, all the cameras have reduced the need and benefit of upright trailer mirrors. 

Might be different if a lot of camper or car hauler width towing is done. 

Packages with all the cameras will still have all the cameras if ordered with tow mirrors.

 

Before adding them, I'd suggest finding one with the tow mirrors to drive. (buddy, demo, rental, etc)

Drive an area, with lots of stops/intersections/corners to deal with. 

 

[David Krueger]

Thanks for the information.

My wife, myself, family and friends have been traveling to Ontario for over 25 yrs. We love fishing there. This year, plans have changed and we are staying in the US. We always went to Perault Falls to a camp that we liked. Well,  it was sold and we don't care for the new owner or what he's doing to the camp. We still like going to the Dryden area in the fall but, That's on hold for now as well. 

Thanks again for all of your help.

[redwngr]

13 hours ago, David Krueger said:

Thanks for the information.

My wife, myself, family and friends have been traveling to Ontario for over 25 yrs. We love fishing there. This year, plans have changed and we are staying in the US. We always went to Perault Falls to a camp that we liked. Well,  it was sold and we don't care for the new owner or what he's doing to the camp. We still like going to the Dryden area in the fall but, That's on hold for now as well. 

Thanks again for all of your help.

 

Mom spent part of her childhood at the mine in Red Lake --  I see it's up the road from Perault Falls

 

That's seriously north from me.

I'm on the north shore of Lake Erie.

[David Krueger]

I did a little reading about the LM2 vs LZO

The LZO looks to have a quite abit of improved air flow at the turbo. That would equate to more power and better mileage. 

  So if you live near Lake Erie you must be used to heavy snow and cooler temps. Whenever we drive through Superior the temperature drops. Living by Lake Erie must be similar. We are going fishing on Lake Erie in September. Just for 1 afternoon on a charter boat. I am fortunate to have a wife that enjoys fishing too. 

[newdude]

On 7/28/2024 at 8:22 AM, David Krueger said:

 I found a set of Mirrors, Ineed to check to make sure that they will fit my truck before I buy them. DS 84994407 and PS 84994408. 

 

 

 

Those are Chevrolet only.  

 

You need 87864007 and 87864006.

[David Krueger]

So, do you know if these have power fold, heated and cameras? Do I need to install a new wire harness with them? Do you have a part number for the harness?

Thank you for your help, I really apreciat it.  

[jw63]

OP - If I may offer some assistance from experience.

 

On my '21 Sierra, I recently tried going from tow mirrors (with tech package [360 view camera]) to standard denali mirrors with the camera.  Thought it would be a straight up swap.  The mirrors mounted up just fine, but the mirror lights were all messed up (coming on with headlights), and the 360 camera view was skewed due to the different camera position.

 

I tried doing some research at the time of said project.  You would definitely need new wire harnesses for the doors to correct the lighting issue. 

 

The camera issue (if you want the 360 view to still be usable) is a different story.  Dealership did not know if the BCM flash is in the computer for the standard mirrors (going from factory tow mirrors to standard we thought the original BCM flash may be in the computer).  In your case, you would need the tow mirror BCM flash, which I would confidently say is not in your BCM.  And unless the dealer knows how to get and add that themselves, you'd be SOL in regards to the 360 view.

[David Krueger]

So what did you do with the mirrors that you took off? Are they for sale? 

[redwngr]

"Diesel Hub" website has some good spec info about GM/Ford/Ram diesels and transmissions.

 

Including this story about LM2, and they have added LZO info.

3.0 Duramax LM2 & LZ0 Engine Specs, Info, History (dieselhub.com) 

 

 

DieselHub lists a bunch of the differences with the LZO  -- 

 

[David Krueger]

Interesting to know about the oil pump repair. I'll have to keep that on my raidar now. I wonder if adding a second DEF injector increases the amount of DEF used.

Thanks for the Information.