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  1. #1

    Unhappy DoD AFM Issues on 2008 5.3

    Hi...My name is Bud and I'm a Burb-a-holic.

    Bought this 08 in October of last year with 130xxx miles on it. Super clean little Burb. Started getting random "Low Oil Pressure-Stop Engine" warnings an SES lights within a few weeks of buying it. Also was getting random "Service Stabilitrak/Service Traction Control" warnings also accompanied by a SES light. In every instance, shutting off the engine for 15 seconds and restarting it made the warning go away. SES would linger for 24 hours or so and go out. Read a little on line about the symptoms and deduced it was a common failing associated with AFM.

    Last week, the "Service Stabilitrak/Service Traction Control" warning came on while pulling my boat, and a lifter started hammering. When it wouldn't subside after shutting down the engine in repeated attempts, I had it towed to a friends house who's a retired ASE Certified Master Technician. He researched the collapsed lifter syndrome that seems rampant, and replaced the lifters on the right bank, cylinders 1,4,6, and 7, and cleaned the VLOM filter.

    After he got it reassembled, it idled fine, and had no codes or warnings. After driving it a mile or so, it showed pending code P3401, P3425, P3441, and P3449, and ran like crap. If he clears the codes, they immediately come back upon starting the engine as pending.

    Any solid suggestions would be greatly appreciated. He's been told by a past L1 he used to work with to test the voltage and ground to the solenoids on the VLOM. Will changing the VLOM fix this, or is this an issue with the ECM?

    I'm totally bummed. I've got a grand invested and it's not right, and I feel my mechanic is doing what he can, he's just not real familiar with the DoD AFM 5.3's.

  2. #2

    Default

    I found this description on another site:
    To provide maximum fuel economy under light load driving conditions, the engine control module (ECM) will command the displacement on demand (DoD) system ON to deactivate engine cylinders 1 and 7 on the left bank, and cylinders 4 and 6 on the right bank, switching to a V4 mode. The DoD systems use an electro-hydraulic actuator device called the valve lifter oil manifold (VLOM) assembly. The VLOM consists of 4 electrically operated normally closed solenoids that directs engine oil pressure to the deactivating DoD valve lifters. All 4 VLOM solenoids are connected in parallel to a fused ignition 1 voltage circuit supplied by the powertrain relay. The ground or control circuit for each solenoid is connected to an individual low side driver internal to the ECM. When all enabling conditions for V4 mode are met, the ECM will command the low side driver to turn ON, grounding each VLOM solenoid control circuit, in engine firing order sequence.

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors, http://www.gmtruckclub.com/forum/sho...5-GMC-Yukon-XL
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

  3. #3

    Default

    I think I am getting a headache, Pikey. I cannot comprehend.

    I hate AFM. If you buy a V8, why would you want it to run on just 4 cylinders? That is just wrong.
    2011 Chevy Silverado LT 4WD 30k miles
    2001 Suburban 2WD, 5.3, V8 185k miles
    1993 964
    1996 318TI

  4. #4

    Default

    Quote Originally Posted by bazar01 View Post
    I think I am getting a headache, Pikey. I cannot comprehend.

    I hate AFM. If you buy a V8, why would you want it to run on just 4 cylinders? That is just wrong.
    You could always get a tune and disable the DoD completely. I don't know if it would stop throwing the codes but, it would be 8 cylinders all the time. I am not sure if over the counter tuners are able to disable the system or if you would have to have someone do a custom tune.

    "The ground or control circuit for each solenoid is connected to an individual low side driver internal to the ECM. When all enabling conditions for V4 mode are met, the ECM will command the low side driver to turn ON, grounding each VLOM solenoid control circuit, in engine firing order sequence."

    I wonder if you just disconnected the "ground or control circuit" wire described
    above, if that would disable the dod.

    Last edited by Pikey; 05-22-2012 at 08:41 AM.

  5. #5

    Default

    Problem solved. Had to have it towed to a dealer. Short circuited Valve Lifter Oil Manifold (VLOM). Labor and parts $723.00.

    The failing VLOM caused the lifter collapse and disabled the traction control and stabilitrak to reduce load on the engine. Hence the Service Stabilitrak/Traction Control warnings I was getting.

    I hope someone effectively gains something valuable at my expense from what I've posted here. I'm certainly disappointed with the lack of response I got to my initial post on this issue.

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