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Pulling DFM fuses

03blackz71
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03blackz71 Senior Enthusiast

03blackz71

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18 hours ago, Firehawk99 said:

Well I tried this and my truck ran like crap! It was shifting all wonky and started hard. I put them back in and it's back to normal. I have a 21 6.2 trail boss.

 

I think the fuse numbers are for the 5.3l.     The 6.2l might be different.

 

 

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BlancoSilverado
BlancoSilverado

Alright everyone,    First went for a drive and verified that i can see the DFM activate, which i saw. i am using an Autel MP808   i pulled over shut off the engine pulled fuse 60

voided3
voided3

That's a bummer. I would be so happy if there was a way to make it so "D" was the same as "L7" on the gear selector so I wouldn't have to toggle up every single time.  I'd be even happier if cylinder

Firehawk99
Firehawk99

Well I tried this and my truck ran like crap! It was shifting all wonky and started hard. I put them back in and it's back to normal. I have a 21 6.2 trail boss.

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WeGone Enthusiast

WeGone

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Posted
1 hour ago, 03blackz71 said:

 

I think the fuse numbers are for the 5.3l.     The 6.2l might be different.

 

 

 

Can anyone confirm on 6.2?

Silverado4x4 Senior Enthusiast

Silverado4x4

Posted
Posted (edited)
19 minutes ago, WeGone said:

 

Can anyone confirm on 6.2?

Nope same fuse numbers. If you're unsure the fuse numbers are in the back part of your owner's manual.

Edited by Silverado4x4
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JohnH4260 Enthusiast

JohnH4260

Posted
Posted

The images below are from pages 352-354 in my 2021 GMC Sierra owners manual. In the engine compartment fuse box, it shows #60 and #67 are the Active Fuel Management 1 and Active Fuel Management 2 fuses. Maybe there’s another system involved as well. 

054858C1-D349-4FBE-BED9-F98DB474D369.jpeg

EB5C8F19-6556-4F7D-8FEF-3BF953F783B2.jpeg

D979D0BA-671D-41DA-A930-CF3E7C01D056.jpeg

kmeleon Enthusiast

kmeleon

Posted
Posted

I hooked up to my Bluetooth scan tool yesterday and I cannot see anyway to monitor how many cylinders are active in real time. I do believe pulling the fuses works but I have no way of proving it. 

RedLT Enthusiast

RedLT

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Posted
On 12/19/2021 at 3:42 PM, voided3 said:

Driving in L7 on the 8-speed or L9 on the 10-speed does disable DFM on the L84 5.3 or L87 6.2 with DFM.

 

Driving in L8 on the 8-speed or L10 on the 10-speed, however, does not; you have to lock out the final overdrive gear to disable it. Driving in L8 or L10 is the same as D on these trucks.

Sorry if it's a dumb question but what does driving in L7 do? The truck only shifts gears 1 through 7? Is DFM beneficial when traveling long distance and disable DFM (L7) when driving around town?

WeGone Enthusiast

WeGone

Posted
Posted

Its my understanding As long as your driving in one gear under the highest you have using L? the cylinder cancellation does not activate. I use L9 under 70mph.

voided3 Enthusiast

voided3

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Posted
On 12/28/2021 at 10:51 AM, RedLT said:

Sorry if it's a dumb question but what does driving in L7 do? The truck only shifts gears 1 through 7? Is DFM beneficial when traveling long distance and disable DFM (L7) when driving around town?

Correct, using "L" limits your gear range. If you have L1 through L7 selected, DFM is disabled. If you are driving in D or L8, DFM is active. I drive in L7 all of the time, but our highway speed limits are only 55-65 around here. Our truck with the 3.23 rear end turns 1900 RPM at 65 MPH in 7th gear and I still squeak out 19 to 20 MPG on the highway.

BlancoSilverado Enthusiast

BlancoSilverado

Posted
Posted

I might try this in the next few days,

I do have a scan tool that tells me if the DFM is activated and which cylinders they are activated. I will also post any codes that become present. 

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WeGone Enthusiast

WeGone

Posted
Posted
1 hour ago, BlancoSilverado said:

I might try this in the next few days,

I do have a scan tool that tells me if the DFM is activated and which cylinders they are activated. I will also post any codes that become present. 

 

looking forward to the results.

kmeleon Enthusiast

kmeleon

Posted
Posted
8 hours ago, BlancoSilverado said:

I might try this in the next few days,

I do have a scan tool that tells me if the DFM is activated and which cylinders they are activated. I will also post any codes that become present. 

Please do! Nobody has been able to know for sure if this works. I'd like to know 100%

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