Jump to content

Pulling DFM fuses

03blackz71
 Share

Recommended Posts

BlancoSilverado Enthusiast

BlancoSilverado

Posted
Posted (edited)

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 and 67 and started the engine back up. no CEL, no codes in any other module. hit the main road and pulled my foot off the pedal(still light pedal to keep speed, noticed that the DFM was activating.  Pulling the fuses does NOT disable the DFM. 

 

I **saw** that the hood status was on the DFM page, i pulled over popped the hood and verified that the hood was properly latched and continued, immediately the dash reminder came on(to tell you the hood is open) and DFM was still not disable. 

 

Sorry guys i wish this would of worked. I wonder what those fuses actually do?

 

FYI i was that DFM is activated when you're off the petal and coasting it seems to default to pistons 1 &3.

Edited by BlancoSilverado
** added more info**
  • Like 4
  • Thanks 1
  • Replies 67
  • Created
  • Last Reply

Top Posters In This Topic

Popular Days

Top Posters In This Topic

Popular Days

Popular Posts

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.

Posted Images

RedLT Enthusiast

RedLT

Posted
Posted
4 hours ago, BlancoSilverado said:

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 and 67 and started the engine back up. no CEL, no codes in any other module. hit the main road and pulled my foot off the pedal(still light pedal to keep speed, noticed that the DFM was activating.  Pulling the fuses does NOT disable the DFM. 

 

I was that the hood status was on the DFM page, i pulled over popped the hood and verified that the hood was properly latched and continued, immediately the dash reminder came on(to tell you the hood is open) and DFM was still not disable. 

 

Sorry guys i wish this would of worked. I wonder what those fuses actually do?

 

FYI i was that DFM is activated when you're off the petal and coasting it seems to default to pistons 1 &3.

Was really wishing it did the trick, but I guess that would be too easy. Thanks for verifying it.

  • Like 1
Silverado4x4 Senior Enthusiast

Silverado4x4

Posted
Posted

Well let me throw this in there being the fuses are pulled the computer might be throwing the signal to activate the lifters thus seeing it on the scanner, but they are not being activated due to the fuses being pulled much like a light bulb removed from a socket, you turn the light switch on it sends the power to the socket but won't work due to no bulb. :dunno:

  • Like 1
voided3 Enthusiast

voided3

Posted
Posted
47 minutes ago, Silverado4x4 said:

Well let me throw this in there being the fuses are pulled the computer might be throwing the signal to activate the lifters thus seeing it on the scanner, but they are not being activated due to the fuses being pulled much like a light bulb removed from a socket, you turn the light switch on it sends the power to the socket but won't work due to no bulb. :dunno:

That's a really good point; the computer would still be sending the signal and the scan tool would pick it up, but there's no power to the solenoids (I assume) with the fuses pulled.

 

I know on our L84 5.3 truck with the 8-speed, DFM is painfully obvious if you maintain precisely 31 MPH on flat ground as that is prior to a transmission up shift point at 32 MPH (it sounds like a helicopter in the cab...). If someone with the same setup wanted to try this with and without fuses, that would be pretty conclusive for me.

 

I'm really tempted to try this myself, but I've already had four lifters replaced and I have extended component coverage on the engine as a result, so I'm a bit chicken to try anything that would potentially void that as I know it's going to happen again. This does have me hopeful, though, as it doesn't doesn't seem to set any codes when you pull the fuses, at least.

BlancoSilverado Enthusiast

BlancoSilverado

Posted
Posted
3 hours ago, Silverado4x4 said:

Well let me throw this in there being the fuses are pulled the computer might be throwing the signal to activate the lifters thus seeing it on the scanner, but they are not being activated due to the fuses being pulled much like a light bulb removed from a socket, you turn the light switch on it sends the power to the socket but won't work due to no bulb. :dunno:

That is a really good point. What we really need to find out is what are those fuses powering? I don't have access to a wire diagram.

voided3 Enthusiast

voided3

Posted
Posted

Ok, I tried it. Based on the fuel economy readings and tell-tale vibrations, DFM was still active in D with the fuses removed. I switched between L7 and D on a few low speed neighborhood roads and also cruised up to 65 MPH on the highway to try this out. Looks like I'm firmly in the "L7 for Life" club.

  • 2 weeks later...
kmeleon Enthusiast

kmeleon

Posted
Posted
1 hour ago, Deadstockpomp said:

I started the thread on the trailboss forum. I just wish we can figure out what the fuses do. If it does not disable it then what is the purpose of them? It just makes no sense 

Agreed, mine are still out. 

M1ck3y Senior Enthusiast

M1ck3y

Posted
Posted

Guys... I haven't really read any of this thread; but there's no fuse you can pull that will disable dfm. Dfm operation is controlled by the ecm, and can only be altered through tuning. 

WeGone Enthusiast

WeGone

Posted
Posted
10 hours ago, M1ck3y said:

Guys... I haven't really read any of this thread; but there's no fuse you can pull that will disable dfm. Dfm operation is controlled by the ecm, and can only be altered through tuning. 

Added a Pulsar LT to disable mine.

  • Like 1
M1ck3y Senior Enthusiast

M1ck3y

Posted
Posted
3 hours ago, WeGone said:

Added a Pulsar LT to disable mine.

 

3 hours ago, WeGone said:

Added a Pulsar LT to disable mine.

 

Nice! I didn't know they managed to figure something out. But yes, that's still through tuning.

xtrythis1 Enthusiast

xtrythis1

Posted
Posted

Interesting topic, shame this doesn't work. I have a Range OBD2 DFM disabler but for the first 5 to 10 miles it still allows DFM to activate which is annoying and not great for a cold engine.. I just leave my trans in L7 (8 speed) and keeps it from kicking on until i hit the 10ish mile mark on a drive. Once i hit around 10 miles or so I can put it in D and runs as it should on all 8 cylinders all the time... until i turn the truck off again then have to start the whole process over again. UGH

NOCO Boss New Member

NOCO Boss

Posted
Posted

There is a lot of interesting information in this article. It explains that equipment/wiring/etc. for the DFM can be present, but if the vehicle has RPO YK9 (was built without DFM) the ECM can’t activate it.  I guess this explains why someone without DFM still has the fuses in the block. 
 

https://gm-techlink.com/?p=14558

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.

  • Forum Statistics

    250.5k
    Total Topics
    2.7m
    Total Posts

  • Member Statistics

    342,894
    Total Members
    8,960
    Most Online
    TopBo
    Newest Member
    TopBo
    Joined

  • Who's Online   4 Members, 0 Anonymous, 965 Guests (See full list)

  • Latest Articles

  • Posts

    • 81mmcat
      Higher oil pressure after DFM shut off

      By 81mmcat · Posted

      Can anyone explain why the oil pressure runs higher after the DFM is shut off?  just installed the Pulsar Lt.
    • fm2176
      New to Me 2010 SLE (Quirks, Issues)

      By fm2176 · Posted

      Thanks!  I figured as such; GM and other manufacturers have used standard parts and harnesses across trim levels and such for decades.  I pulled the blank accessory cover off of my commuter van (a 2016 or so Chevy 15-passenger) years ago and found the plug for a USB outlet.  It wasn't connected to anything, though (I tried swapping in an outlet from another van).  I was a GM Tech years ago (late-90s) and was pretty familiar with my 2006.  I might be wrong, but I view newer vehicles (pretty much anything made in the past 20 years) as being a lot more plug and play.  Meaning, more unused wires and plugs unless you have the Mack Daddy of vehicles.    
    • Coastie05
      It's Been a Long Time...

      By Coastie05 · Posted

      Welcome back!
    • davester
      New to Me 2010 SLE (Quirks, Issues)

      By davester · Posted

      not all plugs will be used.  gm uses more generic harnesses that support most/all options, and if your truck doesn't have a specfiic option, the plug won't be used (commonly will have a dummy insert in the plug , or it'll be taped up, but some may just be left as is).  But it's sldo possible some p.o. has installed the wrong/cheaper parts that aren't correct for your vehicle...
    • fm2176
      New to Me 2010 SLE (Quirks, Issues)

      By fm2176 · Posted

      First off, I'm not trying to just get easy advice/fixes for the issues I've noticed so far.  I'll be combing through the site via searches and such, and if past experiences are any indication, should find what I need.  For the sake of conversation, though, I figured I'd post the handful of things I've noticed in the 12 hours since buying my 2010 SLE CCSB.     Indicator lights: Airbag and TPMS.  The tire pressures aren't reading for any of the wheels, so I'm pretty certain the sensors were either removed, are damaged, or are otherwise inoperable.  I used to mount and balance tires 25 years ago but am pretty much ignorant when it comes to TPMS.  My 2006 didn't have the sensors and this might be the fourth vehicle I've owned that does.     Radio: Rear speakers aren't working.  I removed the driver's side rear door panel and checked the speaker and wiring.  I also removed the sill and b-pillar covers to check the wiring.  A few minutes of Google Fu showed that this is potentially a head unit issue.    Switches: Power mirrors don't turn left/right.  I ordered replacement driver's door switches that should arrive tomorrow.  The windows and locks work but it was only about $20 for all of them.  The driver's side rear window switch lets the window down but won't put it back up.  I think the passenger rear doesn't work at all.  In the coming days/weeks, I'll break out my multimeter to check all of that.   Unknown wiring harness: There's a box attached to the front driver's side of the engine compartment, right where the second battery shelf is located.  There are three plugs, one of which looks like it fits a standard headlight-style bulb (9007 or similar).  It doesn't look like it's plugged into anything.  I'll do some digging and if I don't see anything elsewhere on the site, post some pictures here.   Unknown plugs on brake booster: There are at least two female plugs on the brake booster that aren't being used.  I think it might be a replacement/aftermarket, so maybe those are used for a different application, as there don't seem to be any unplugged harnesses and no indicator lights are on.   Little squeaks when turning: Sounds almost like a bushing around the bed of the truck.  I'll have to pay close attention as I get more familiar with the truck.   Clunk on acceleration: possibly the infamous drivetrain clunk.  My 2006 had it and I'm just not familiar enough with this truck yet to fully grasp what it is.   Anyway, my apologies for the vague and all over the place post.  This truck is new to me, and it's been four years since I drove my 2006.  With 200k miles, I know I'll need to learn this truck quickly to avoid having any major issues, despite being confident it's got much more life to it.  My 2006 had nearly 320k on it when I parked it (nearly 300k of which I put on the truck), and it was still drivable then, though I suspected the head gasket might have blown.  I'd hoped to have that truck back by now, but it's gone forever, as I detailed in my reintroduction thread.  

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...