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Tranny trouble?

Discussion in 'GM Powertrain' started by getawaycars, Aug 18, 2010.

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  1. getawaycars

    getawaycars New Member

    My 97 Suburban K1500 4x4 with a 4l60e trans (183,000mi) seems to be developing issues.

    When pulling a hill at about 45-50 mph, the trans seems to go in and out of overdrive.
    Two weeks ago, i dropped the pan and changed the fluid (about 4.5 qts) and filter.
    A week later, after driving about an hour, it shifted hard a few times from 1st to 2nd.
    I stopped to check the fluid, which was full. When I drove away it shifted fine from then on.
    Another week later (today), it shifted hard (1-2) after highway driving for about 30 min.
    Once I stopped it was fine. After another highway run (an hour later), the check engine light came on (code p1870), and it shifted hard (1-2 only) until i stopped, since then it's been ok.
    Any ideas?
    Last edited: Aug 18, 2010
  2. 95Chevyk1500

    95Chevyk1500 New Member 100 Posts

    yup. mine does the same thing. its because of a worn part that causes a slip. and when the computer detects the slip it goes into "limp mode" and thats shifting hard from 1-2.
    I dont remember what tyhe worn part is called but i beleive it is the valve body
  3. 99'HEARTBEAT

    99'HEARTBEAT Moderator Staff Member Platinum Contributor 1000 Posts 100 Posts

    A Code.....P1870......is telling you there's a Problem with the Control Valve Body in your Transmission.

    Below is a G.M. Service Bulletin,that might apply to your Vehicle,
    TSB # 01-07-30-023A
    Harsh 1-2 Upshift, SES, MIL, or CEL Illuminated, DTC P1870 Set (Replace Valve Body)
    1996 Buick Roadmaster
    1996 Cadillac Fleetwood
    1999-2000 Cadillac Escalade
    1996-2000 Chevrolet Camaro, Corvette
    1996-2000 Pontiac Firebird
    1996-2000 Chevrolet and GMC Light Duty Truck Models
    1996-2000 Oldsmobile Bravada
    with 4L60-E Automatic Transmission (RPO M30)
    Built Prior to January 15, 1999 (Julian Date 9015)
    This bulletin is being revised to update the Parts Information

    Please discard Corporate Bulletin Number 01-07-30-023 (Section 07 -- Transmission/Transaxle).
    Condition,
    .......Some customers may comment on a harsh 1-2 upshift and the Check Engine Light or Service Engine Soon indicator is illuminated.
    Diagnosis,
    .......Typically, these vehicles will have been driven more than 32,000 km (20,000 mi) before this condition occurs.
    .......The scan tool may show a DTC P1870 set as a history code.
    ........A harsh 1-2 shift or DTC P1870, caused by wear in the control valve body, may be difficult to duplicate when the transmission temperature is below 93°C (200°F).
    Cause,
    ......The condition may be due to wear in the control valve body. This wear occurs in the bore that contains the TCC isolator and regulator valves, and results in poor, or no, TCC apply

    Important,
    ......DTC P1870 is a type B code. The conditions for setting the P1870 DTC must occur on TWO CONSECUTIVE TRIPS (ignition cycles, with a drive cycle) before setting a P1870 history code.
    ......When the conditions for setting DTC P1870 are met (first trip), the PCM commands maximum line pressure and harsh 1-2 shifts are the result.
    ......This may result in a harsh 1-2 shift with no history code if the conditions for setting the DTC required for the second trip are not met, on two consecutive trips (Ignition cycles, with a drive cycle).
    ......When the conditions for setting the DTC are met, on the second consecutive trip, a DTC P1870 is stored as a history code.
    ......When the P1870 code is stored, the PCM will turn on the Service Engine Soon (SES), ......Check Engine Light (CEL), or Malfunction Indicator Lamp (MIL).

    Correction,
    Install a control valve body with the revised TCC regulator and isolator valves. These valves are used in all transmissions produced after January 15, 1999 (Julian Date 9015), and all of the service parts currently available through GMSPO contain revised TCC regulator and isolator valves.

    Also,
    ......If all of the following conditions are true, it is not necessary to rebuild the transmission or to replace additional transmission components beyond the control valve body.
    .......Transmission operation is normal before the transmission reaches operating temperature, or before DTC P1870 is set (no slips, flares, or missing gears).
    ......The torque converter is not blue or overheated.
    ......The transmission fluid is not burned or has no burned odor.
    ......The transmission fluid pan contains no abnormal debris (clutch material, bronze, brass, or metal fragments).
    Last edited: Nov 5, 2010
    1 person likes this.
  4. silveradotrailblazer

    silveradotrailblazer New Member 1000 Posts 100 Posts

    I think TransGo has a repair/updated part to fix this problem.
  5. getawaycars

    getawaycars New Member

    95chevyk1500 - How long has yours been doing this?

    '99 Heartbeat - thanks for the info

    Has anybody tried Lucas Oil Trans Fix on this issue. Someone told me it fixed theirs.
  6. murdog94

    murdog94 New Member 1000 Posts 100 Posts

    99 Heartbeat. THat is some great info!! To bad no light but hard 1-2 shift for me... We shall see.

    And Getaway- I havent used it and some people have that have had luck. It all depends if something is gumming it up or if you need to replace the Valve body as the TSB mentions.
  7. Jcloud

    Jcloud New Member

    My truck does the same thing! it is a new transmission in there and has about 57,000 miles on it. the only time my 1st-2nd shift is smooth is if its not up to regular running temp or if i go up to 3000 RPMS it will shift smooth. i have been wondering what has been causing it to have that harsh shift. Very good info!!:great:

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