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  1. #1
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    Default 4l60e slipping after warm up

    Hey guys just joined the forum after picking up a 96 silverado with 118,000 on it as a little project and I hope someone can answer this one for me. The truck s ok before it warms up but once it does it slips bad in any gear, won't even move. Could this be a valve body problem or should i just have it rebuilt? It would suck to have it rebuilt if I don't need to.

  2. #2
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    That sounds like a lot more than just a valve body problem, more like no pressure on the clutch packs once the transmission warms up. Before throwing money at it, it will pay dividens to diagnose it correctly on the first go around. Check the obvious first, like the fluid level. Than move on to a line pressure test or dropping the pan and checking if the filter is seated correctly on the transmission and has not cracked, or fallen off. Either way if you try driving it like this you'll burn up the transmission.

    Here is something interesting I found:

    Some of the early 1996 GM vehicle lost the internal ground in the computer.
    There is a service bulletin out by Gm to reroute some wires and add one.
    1996 4L60/80E, 1-2 Slip/Flare, No 3rd or 4th, erratic line pressure and/or poor line rise, shudder on take-off, sometimes accompanied by Code P1870. These conditions can all be caused by a poor internal ground in the VCM.
    All 1996 Chevrolet and GMC C/K, S/T, M/L, G/P Models must have the harness updated per GM Service Bulletin 667103A. Make repairs using GM Service Kit Part # 12167310, unless this flag label is attached to the clear branch. Or you have a corrected VCM with service # 16244210 on the VCM ID label.
    This may or may not be the problem. You can have any number of inputs to the computer causing your issue. It could also be a bad transmission.
    Edit:
    Here is more on the same...
    00-07-30-026 - (12/21/2000) Automatic Transmission 1-2 and/or 2-3 Upshift Slip/Flare, No 3rd or 4th gear, Launch Shudder (Revise VCM Wiring)
    1996 Chevrolet and GMC C/K, S/T, M/L, G1, G2, P3 Models
    1996 Oldsmobile Bravada
    with VCM and 4L60-E (M30) or 4L80-E (MT1) Automatic Transmission

    This bulletin is being reissued to ensure that correct procedures are followed for this condition. Please discard Corporate Bulletin Number 66-71-03A (Section 7 -- Automatic Transmission).

    Condition
    Some owners may comment that the automatic transmission has either a slip or flare on the 1-2 and/or 2-3 upshift, or no 3rd or 4th gear, or launch shudder. Upon investigation, the technician may find a DTC P1870 stored in the VCM.

    Cause
    A poor internal ground between the two circuit boards of the VCM may cause the VCM to command erratic line pressure at the pressure control (PC) solenoid valve.

    Correction
    Using harness jumper wire and instruction kit, P/N 12167310, revise the wiring harness at the VCM connector. Corrections were made to the VCM beginning 2/14/96. The corrected VCMs are identified with service number 16244210 on the VCM identification label.

    Procedure
    The following is a summary of the instructions included with the service kit:
    1. Remove the negative terminal from the battery.
    2. Move the wire located at connector J3 (WHITE/GREY/CLEAR), pin 18 to connector J1 (BLUE), pin 23.
    3. Install the jumper wire between connector J2 (RED), pin 26 and connector J3 (WHITE/GREY/CLEAR), pin 18.
    4. Install the tag included in the kit around the VCM wiring harness. This tag notes that the wiring harness has been modified.
    5. Reconnect the negative battery terminal.

    Road test to verify that the condition has been corrected. If any of the following conditions are noted, the transmission should be repaired or replaced using the most cost effective method. Canadian dealers should repair the transmission.
    1. Transmission fluid oxidation or excessive sediment.
    2. Transmission slip or flare after this service fix is performed.
    3. DTC P1870 is stored on a 4L60-E (M30).

    The following tools are available from Kent-Moore (1-800-345-2233) for use in removing and relocating the VCM wires:
    1. J 41758 Terminal Tool; used to remove the wire from the VCM connector.
    2. J 41759 Punch; used to punch a new hole through the connector seal.

    Parts Information
    Part Number: 12167310
    Description: Harness Jumper Wire Kit
    Qty: 1
    Last edited by DGA1; 04-06-2012 at 01:33 PM.

  3. #3
    Metalworking Madman JollyGreen's Avatar
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    Is it after you are warmed up and the truck has been over 50mph for a few miles? Any codes? Could be the torque converter. Mine slips from 1st to 2nd only, and only after it's been over 50mph when warm.

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