V8 mode 4 cylinder

Discussion in 'Performance' started by Don S, Nov 6, 2019.

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  1. Don S

    Don S TYF Newbie

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    Just bought this Tahoe Friday. Never see it switch from V8 to 4 cylinder mode on dash.
    What among my list of issues will keep it from working?
    1.Oil sending gauge shows to be out and not reading any oil pressure on gauge.
    2. C0660 suspension code
    3. Tire pressure not reading on rear wheels according to dash messages.
    4. Cruise control won’t set.
    5. Pedals won’t move up and down with switch on dash.
    Thanks
     
    Last edited: Nov 6, 2019
  2. HiHoeSilver

    HiHoeSilver Away!

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    First things first. Tell us about "this" Tahoe. Year, trim level, miles, etc?

    1. Did it show oil pressure when you bought it? Have you checked the pressure with a mechanical gauge? Two things, the sensors die, but the pickup tube o ring is also a known source for low pressure problems.

    2. Trouble with the exhaust valve for the air ride system, looks like. There are some good threads and youtube videos that talk about the system and how to troubleshoot it. Lots to go wrong there. Start planning your autoride delete, imo.

    3. Could try a relearn. Could be dead batteries in the sensors.

    4. Check some fuses, but likely your brake switch.

    5. Check some more fuses. Inspect wiring down by the pedals. Maybe your cruise issue and this are related somehow?
     
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  3. swathdiver

    swathdiver Full Access Member

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    The oil pressure sending unit will keep AFM from operating. Under the sensor is a little filter, clean or replace it while you have it apart. Get a Tech-2 so you can work on it properly. Under the dash is a brake switch, about $10-20 ACDelco, this is usual culprit for cruise not working. Takes about ten minutes to replace. Do not use anything but GM OE or ACDelco Professional.

    25981009 or D1539J
     
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  4. iamdub

    iamdub Hold on... Lemme overthink this for a bit...

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    I'll echo what Nate and James mentioned.

    Other than the gauge reading no oil pressure, they're all common and fairly easily resolved issues. I'm guessing since you didn't say the engine is tapping or knocking that you actually do have oil pressure and it's just a gauge or sensor issue.
     
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  5. Don S

    Don S TYF Newbie

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  6. Don S

    Don S TYF Newbie

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    Runs great no over heating thx
     
  7. Don S

    Don S TYF Newbie

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  8. Don S

    Don S TYF Newbie

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    Great advice thx
     

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