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4L60E Slips out of 4th

This is a discussion on 4L60E Slips out of 4th within the Technical / Maintenance forums, part of the General Discussion category; Did you get it fixed yet? Interested to see what you found....

  1. #21
    Registered User Randy_W's Avatar
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    Re: 4L60E Slips out of 4th


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    Did you get it fixed yet? Interested to see what you found.
    RandyW
    '02 Short Bed/ Reg Cab/ LS1/SS wheels,3.73 Gears

    '96 Tahoe 2dr 4x4


  2. #22
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    Re: 4L60E Slips out of 4th

    UPDATED

    Ok, so I finally got the o-rings and seals to rebuild the 2-4 servo. The servo looked like it was in good shape with no obvious signs of wear or porosity. The trans shop in town that sold me the rebuild kit also gave me a spring to replace on the second apply piston and pin assembly as well. The 4th apply piston slid surprisingly easily, as did every other component in the servo.

    I replaced all the rings on the servo, and even after lubricating them before assembly, they were much much tougher to get back together, really showing how much the old ones wore. I also replaced the spring on the 2nd apply piston, but neglected to get a new return spring while i was at the shop That really frustrated me, since I found out on dis assembly that the spring on the 2nd apply piston was literally half as firm as the new one they gave me... gotta wonder how many millions of times that thing cycled in 215,000 miles to get that soft...

    Anyhow, I got the truck put back together, and noticed a firmer shift shift into second, but nothing drastically different. The rest of the transmission's operations remains unchanged, including the slip from the original post. Could not swapping the return spring cause this?

    Looks like it's time to order a new distributor from ebay...

    Pete
    Last edited by big pete; 06-21-2010 at 09:33 PM.

  3. #23
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    Re: 4L60E Slips out of 4th

    Sorry for the slow progress, swapped 4 rotors and rear shocks on the car last week too for regular maintenance, only to have the starter quit after 5 years of duty. Honestly surprised it made it that long, with the 10.8:1 compression and sitting that close to the headers, but the overdue regular upkeep and surprise starter failure made the truck a lower priority for a bit there.

    Pete
    Last edited by big pete; 06-21-2010 at 09:37 PM.

  4. #24
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    Re: 4L60E Slips out of 4th

    you actually dont even have to have that spring in (the one that goes gainst the cae) I dont recommend not putting it in however the 3rd oil pushes the servo back on the 2-3 shift to disengage the band some builders dont put the spring back in I always do lol. sounds to me that the band is getting worn out 4th gear puts more load on the band then 2nd, a band that is marginal may not slip under 2nd moderate throttle but slip under 4th moderate due to load. in 4th gear you have the 3-4 clutches and the 2-4 band applied if the band doesnt hold well then you have 3rd gear as the only thing applied in 3rd are the 3-4 clutches and of course the forward clutches this is why it kicks into third gear its not the trans shifting into 3rd its the trans going to 3rd due to the band not holding, a mechanical failure not hydraulic. My suggestion is to take it to a reputable shop or find a builder that you trust or try to do it yourself the 60s really are not that hard. If i can be of any help dont hesitate to ask lol I have walked a few peeps through a build.

  5. #25
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    Re: 4L60E Slips out of 4th

    Yeah, the worn band is what I'm afraid of. I still think it's weird though that the band lets go when load is removed... it doesn't slip into 3rd when the engine is under load, but when the engine is moved from 3/4 throttle going up a hill to 1/2 going down a hill. It seldom does it on level pavement. I would have thought that the band would have slipped as load increased, not decreased. I think you're right and that a rebuild is in my near future to replace the bands and clutches, but I want to check the distributor recommendation first.

    Thanks for offering to help guide me through the rebuild, I've never done more to a trans than swap a torque converter, change a front seal / pump, and now a 2-4 servo ;-)

    Pete

  6. #26
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    Re: 4L60E Slips out of 4th

    Get that new distributer and have it timed. Now one thing you should know, if you get a aluminum one off ebay it will come with a new distributer clamp that doesnt allow the distributer to be turned, use the old clamp and you will be fine, they give you a V6 clamp becouse that ditributer shaft is the same on the 4.3. So just use your old clamp. Im pretty sure once you change that distributer out and have it timed with a scanner you WILL see a difference.
    97 GMC Yukon. True Duals, Hypertech, 99 Tranny. Punished religiously

  7. #27
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    Re: 4L60E Slips out of 4th

    When I said before
    Set the timing, replace the servos, then get your money ready to rebuild the tranny, it's getting ready to fail.
    , I wasn't trying to be a smartass, my best friend owns a dealership and is himself a transmission guru. I don't know how many 4l60e's including mine, I've heard of with that exact symptom and I've never seen one yet over 50k or so that didn't need a rebuild to cure, except one '02 Tahoe Z71 that had a cracked sun shell.
    RandyW
    '02 Short Bed/ Reg Cab/ LS1/SS wheels,3.73 Gears

    '96 Tahoe 2dr 4x4


  8. #28
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    Re: 4L60E Slips out of 4th

    UPDATE:

    Since a lot of the local shops are being ghey and wanting to charge me out the ass to have my distributor retimed, I haven't inspected the suspected worn gear on it. I have ordered an Autoxray 6000 so I can take care of business myself. In the mean time though, I wanted to inspect all the solenoids electronically first for faulty solenoids before I crack the pan open. Using various diagrams and bits of info that I was able to scour off the net to break the code of the weird 4 harness connector to the PCM, here's what I was able to find:

    Trans Pressure Control Solenoid Valve: Clear Pins 6 & 16 = 3 - 5 Ohms. Mine was 5.0



    These next solenoids connect to circuit 1020. And, where is 1020? In fuse #20 in the passenger compartment... why couldn't it just be another PIN on the PCM?

    1-2 Shift Solenoid: Red 6 & 1020 = 19 - 24 Ohm. Mine was 23.3
    2-3 Shift Solenoid: Red 4 & 1020 = 19 - 24 Ohm. Mine was 23.6
    Pulse Width Modulation TC Solenoid: Red 7 & 1020 = 10 - 11 Ohm. I'm over the limit at 11.9 <== Possible cause for my malfunction?



    The Torque Converter Clutch Solenoid Valve is supposed to be 21 -26 Ohm, and 3-2 Shift Solenoid should be 20 - 24 Ohm... I have no idea where those meet up with the PCM, but I know that they are energized by the 1020 circuit that is hot when the ignition's on. From what I have found, it looks like they are driven when the PCM grounds them out, completing the hot circuit to drive the solenoid. But, it's strange how signals going to and from those solenoids, entering and exiting the trans, but they never make it back to the PCM. I could not find any pin on the 4 harnesses to the PCM that was labled TCC or 3-2. So, how do you measure the resistance on those without dropping the pan? How in the hell do they talk to the PCM

    Pete
    Last edited by big pete; 06-30-2010 at 10:13 PM.

  9. #29
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    Re: 4L60E Slips out of 4th

    My hat is off to you, you are going the extra mile to diagnose it, I hope it is something cheap and simple. :thumbsup:
    RandyW
    '02 Short Bed/ Reg Cab/ LS1/SS wheels,3.73 Gears

    '96 Tahoe 2dr 4x4


  10. #30
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    Re: 4L60E Slips out of 4th

    Yeah, just trying to exhaust all the options for a quick, simple component swap. Rebuilding when you didn't have to is something I'd rather avoid. Besides, this would be a good spot to post some of the tech on how to test those spots so other can find it for their trucks.

    Pete

  11. #31
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    Re: 4L60E Slips out of 4th

    hey man when you said a few posts up that you aren't sure why this doesn't do it under load, but does it when the laod is removed in 4th gear. that's because the further you have your foot into the pedal, the more pressure epc solenoid will create. this is why you're not slipping underload, however you are when under light throttle. sounds like your 2-4 band is about shot man....sorry to hear the servo didn't help!
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  12. #32
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    Re: 4L60E Slips out of 4th

    Tranny slips in and out of OD/4th?

    First try the brake light pedal switch!

    The servo and dist. suggestions are incorrect!

  13. #33
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    Re: 4L60E Slips out of 4th

    I replaced the brake pedal switch last year when the cruise control was having issues. At first, I thought it was a bad cruise control module, so I got a junkyard special for $40 bucks, and that didn't fix it. The second guess of the brake switch solved that problem and the cruise has worked perfectly ever since.

    I'm hoping that it was a bad torque converter solenoid, but I haven't figured out how to test that one yet without taking the pan off. Since I'm driving the truck usually, I'd rather not fool with that yet unless I know what I need to replace. The torque converter solenoid and the 3-2 solenoid are the two that didn't have a pin on the PCM and I still can't figure out where they meet up with the controller.

    Pete

  14. #34
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    Re: 4L60E Slips out of 4th

    Hey Pete:

    I'm having all and exactly the symptoms you describe. Spoke and test drove with a tranny shop serviceguy and he talked possibly sunshell and claimed my oil was burnt. Said it was new tranny time. That being the case I'll drive it in a nursing manner till it implodes. But in any case I dumped the fluid and filter yesterday and everything got a way way better. I don't think it's gone but the it was cycling in and out of OD every 1 to 2 minutes on highway and now and then in town. First two 10 minutes highway drives I think it slipped out of OD into 3rd once.

    Inspecting the undisturbed trans pan, I noticed a light sheen of copper suspended in the trans fluid and the magnets had probably increased in size by 30 % due to metal accumulation. Thin layer of grime in pan. I think i heard copper colour was baaad. Comments welcomed!

    If you haven't done it drop the pan (yea I hate wearing trans fluid). But keep us posted cause I'm hunting for a cure like my trans is hunting it's OD.
    Last edited by bevbev; 07-05-2010 at 06:33 PM.

  15. #35
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    Re: 4L60E Slips out of 4th

    Quote Originally Posted by sonjaab View Post
    Tranny slips in and out of OD/4th?

    First try the brake light pedal switch!

    The servo and dist. suggestions are incorrect!
    why would you say tha tthe servo suggestion is incorrect? if the 4th servo was leaking you would go back to third as the band would not be applied only the 3-4 pack would be applied in that instance giving you third gear, however the servo has already been ruled out.

  16. #36
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    Re: 4L60E Slips out of 4th

    Sorry to hear about your trans, man. Yes, copper color is bad. It's usually part of the bushings, torque converter, and stuff like that (at least in the Fords that I'm familiar with) because some of them are bronze. Fortunately, I didn't have any metallic particles or globs of nastiness in my fluid last year when I serviced the trans, but who knows what's in there now... at the time though, everything looked really good, even when I cut the old filter open last summer. Nothing to be found. As soon as I get my project car put back together so it can pick up DD duties, the truck's pan is coming down for a look. I think that will be the only way to measure those other two solenoids that somehow don't talk to the EEC.

    Pete

  17. #37
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    Re: 4L60E Slips out of 4th

    This has been beaten about quite a bit, back to the original thoughts, both of you with that problem, if you drive them until they break you could be increasing your cost to repair if you break a bunch of stuff.
    RandyW
    '02 Short Bed/ Reg Cab/ LS1/SS wheels,3.73 Gears

    '96 Tahoe 2dr 4x4


  18. #38
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    Re: 4L60E Slips out of 4th

    UPDATE:

    OK, so I haven't been driving the truck hardly at all, just once or twice a week to keep the fluids circulating and the tires rotating. I put the AutoXray 6000 to it to see what gear the PCM was commanding; however, there is no way for me to see which gear the trans is being told to hold. In my Ford, the AutoXray 6000 shows the position of the shift solenoids, TC lockup / ratio, and commanded gear. Is there any way to see these values on the Chevy? I tried swapping its config from 98 GMC to Generic OBD-II and got even fewer parameters.

    Is there any way to see what gear is being commanded? I can't think of any way to do this without taking it to a shop for a $60 diagnosis that will probably result in "rebuild / replace" anyhow.

    Pete

  19. #39
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    Re: 4L60E Slips out of 4th

    UPDATE:

    OK, so I haven't been driving the truck hardly at all, just once or twice a week to keep the fluids circulating and the tires rotating. I put the AutoXray 6000 to it to see what gear the PCM was commanding; however, there is no way for me to see which gear the trans is being told to hold. In my Ford, the AutoXray 6000 shows the position of the shift solenoids, TC lockup / ratio, and commanded gear. Is there any way to see these values on the Chevy? I tried swapping its config from 98 GMC to Generic OBD-II and got even fewer parameters.

    Is there any way to see what gear is being commanded? I can't think of any way to do this without taking it to a shop for a $60 diagnosis that will probably result in "rebuild / replace" anyhow.

    Pete

  20. #40
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    Re: 4L60E Slips out of 4th

    Interesting subscribing to see the finale outcome.

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