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DoD AFM Issues on 2008 5.3

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by Hairfarmer, May 21, 2012.

  1. Hairfarmer

    Hairfarmer New Member

    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. Pikey

    Pikey Moderator Staff Member 1000 Posts 100 Posts

    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.
  3. bazar01

    bazar01 New Member 100 Posts

    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.
  4. Pikey

    Pikey Moderator Staff Member 1000 Posts 100 Posts

    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: May 22, 2012
  5. Hairfarmer

    Hairfarmer New Member

    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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