P039 – VCC Lockup Problem: Read Archives, Still Have Questions
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Northstar Engines and System Technical Discussion Discussion, P039 – VCC Lockup Problem: Read Archives, Still Have Questions in Cadillac Engine Technical Discussion; ...
  1. #1
    jimusa95 is offline Cadillac Owners Member
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    P039 – VCC Lockup Problem: Read Archives, Still Have Questions



    My 94 Concours started getting intermittent P039 codes 2 ˝ years ago, at only 45,000 miles. My dealer tried replacing the shift solenoids, without success. Now has 55,000 miles. Has always shifted very smoothly, with no hint of a trans problem other than the trouble code.

    Thanks to this forum and other online sources, I now know how to display and decipher the trouble codes, and have also learned about the TSB suggesting an updated PCM prom, which I plan to install.


    But, I don’t want to spend big money doing further repairs on a transmission that feels like its operating perfectly. I’d like to understand what’s happening if the P039 - TCC/VCC LOCKUP PROBLEM code keeps coming back. I've read the forum archives but still have some questions which I hope some of you can help me with. They are:



    1)If I get a P039, and it means the VCC clutch has not locked-up, will the trans still shift into 4th gear and just not have the efficiency of the VCC lockup, or will it not go above 3rd?


    2)After the P039 code sets, is the VCC prevented from trying to lock-up? If so, should I clear out the code as soon as it appears?


    3)If I continue to get intermittent or even permanent P039 codes, any reason why I can’t drive around town, indefinitely, with the VCC not locking up?


    4)What about driving at expressway speeds with the VCC not locking up? Besides getting poorer mileage, am I damaging anything?


    5)If the transmission develops other slippage problems, in addition to the torque converter clutch, won’t I be forewarned with additional trouble codes?



    Thanks

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  3. #2
    BeelzeBob's Avatar
    BeelzeBob is offline I'm a Cadillac Fanatic!
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    Re: P039 – VCC Lockup Problem: Read Archives, Still Have Questions

    The shift solenoids have nothing to do with the VCC apply.

    The VCC diagnostic looks at the slippage across the torque converter by comparing the engine RPM and the RPM from the transmission input speed sensor. When the VCC is applied, the slippage should be reduced considerably and stay within certain RPM parameters. If the slippage exceeds those parameters it assumes that the VCC is slippping too much and/or not applying so it sets the code 39. The slip parameters are a bit too stringent for higher mileage/higher slip limit VCC units so the service prom opens up the window or makes the diagnostic test less stringent. If there is a service prom for the code 39 listed for your car it would be a worthwhile investment, especially if you see an occasional code 39.

    The VCC unit is a viscous coupling so it is designed to creep or slip slightly to isolate the driveline from torque pertubations that are sensed as chuggle or roughness. A TCC (or more conventional Torque Converter Clutch) is a positive lockup with no slip so it is more susceptable to chuggle, especially in a heavier FWD car. Since the VCC unit creeps slightly under normal operation the diagnostic test is tasked with trying to determine if the creep or slip is TOO much in order to set the code 39. The parameters for the test are opened up in the service prom as mentioned so as to make the code less "hair trigger" in it's operation.

    You can use the brake pedal interlock check to disable the VCC at will to see/feel if the VCC is applying and locking up. If you can tell that the VCC is applying, yet the code 39 is setting then likely the service prom will eliminate the false codes. But....possibly the VCC is not applying at all in which case the prom will do nothing and the system needs to be diagnosed and corrected.

    The basic operation and mechanisation of the TCC and VCC is exactly the same so in many context the two items are treated as the same as the terms TCC and VCC are often used interchangably. Just realize that when the VCC applies to lock the torque converter it will still allow a little creep in RPM as opposed to a solid lockup like a TCC. At 70 MPH road load the VCC might slip or creep 50-75 RPM instead of a true lockup. Without the VCC you might see 300 RPM slip across the torque converter so disabling it with your left foot lightly on the brake pedal would show a jump of 100-200 RPM or so if it is working correctly.

    1) The trans will shift normall into 4 even with code 39. You can check this by manually selecting 3 on the shifter and feel the downshift to confirm that the trans is going to 4. When the code 39 is set, try the trans manual downshift with the lever to 3 and feel it. Proof positive that the trans was in 4 if it downshifts to 3 manually.

    2) I believe the code prohibits VCC operation for that ignition cycle if the code sets.

    3) You can drive forever with the intermittant VCC with no problems.

    4) Nothing will be damaged running without the VCC. In fact, if the trans trips the high trans temp switch the protection mode is to disable the VCC to protect the trans anyway....

    5) There are other trans codes that could still set. "Slippage" per se, is not necessairily something that is diagnosed by the PCM anyway, whether or not the VCC is working or not.

    Hope this helps....

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    jimusa95 is offline Cadillac Owners Member
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    Re: P039 – VCC Lockup Problem: Read Archives, Still Have Questions

    Thanks for taking the time to provide such a complete and informative answer. I've been afraid to drive the Concours very far from home. Now that I understand what's happening, I'll feel comfortable venturing out a little further.

    One last question, when I test by manually shifting from 4th to 3rd and back, is it safe to do so at speeds of 50-65 mph?

    Thanks again, Jim

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    jimusa95 is offline Cadillac Owners Member
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    Re: P039 – VCC Lockup Problem: Read Archives, Still Have Questions

    Thanks for taking the time to provide such a complete and informative answer. I've been afraid to drive the Concours very far from home. Now that I understand what's happening, I'll feel comfortable venturing out a little further.

    One last question, when I test by manually shifting from 4th to 3rd and back, is it safe to do so at speeds of 50-65 mph?

    Thanks again, Jim

  6. #5
    BeelzeBob's Avatar
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    Re: P039 – VCC Lockup Problem: Read Archives, Still Have Questions

    Quote Originally Posted by jimusa95
    Thanks for taking the time to provide such a complete and informative answer. I've been afraid to drive the Concours very far from home. Now that I understand what's happening, I'll feel comfortable venturing out a little further.

    One last question, when I test by manually shifting from 4th to 3rd and back, is it safe to do so at speeds of 50-65 mph?

    Thanks again, Jim

    You can shift from 4 to 3 at about any speed less than 130 or so....

    I run cars in manual 3rd at 80 MPH with the cruise on pulling trailers for 400 miles non-stop. Shifting the trans into 3 at 50-65 is loafing along. Remember, 4th gear is overdrive. 3rd gear in your trans is 1:1....that is all transmissions used to have at all was 3 gears with top gear being 1:1. And you weren't afraid to go 80 in those cars without overdrive...same thing as being in 3 or shifting to 3. At full throttle the trans will shift from 3 to4 at about 130 so try to do the 4-3 check below that....LOL..

  7. #6
    jimusa95 is offline Cadillac Owners Member
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    Re: P039 Problem: 99% Solved by New Prom!!

    I installed the new EPROM recommended by G.M. Service Bulletin 87-65-17, and it eliminated 99% of my P039 trouble codes.

    I was getting the P039 trouble code every few starts when accelerating quickly with a cold engine, and also after several hours of non-stop expressway driving. Now, after 1-1/2 months, and a 400 mile expressway trip, I've only had one cold-start PO39.


    The new EPROM cost $47, including shipping, from GMPartsirect.com.


    I had intended to install it myself, which requires removing and reinstalling the car's computer. In my '94 Concours, the computer is way up under the dash behind the glove compartment. After seeing the rat's nest of cables I needed to work around, and the warning sticker about the danger of accidentally setting off the airbag, I chickened out. My local mechanic installed it for me for $85.


    I think it was money well spent to get rid of that nagging trouble code and thank those on this forum for tipping me off to this fix. My dealer never mentioned it.

    Jim

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    wake's Avatar
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    Re: P039 Problem: 99% Solved by New Prom!!

    Quote Originally Posted by jimusa95
    I installed the new EPROM recommended by G.M. Service Bulletin 87-65-17, and it eliminated 99% of my P039 trouble codes.

    I was getting the P039 trouble code every few starts when accelerating quickly with a cold engine, and also after several hours of non-stop expressway driving. Now, after 1-1/2 months, and a 400 mile expressway trip, I've only had one cold-start PO39.

    I think it was money well spent to get rid of that nagging trouble code and thank those on this forum for tipping me off to this fix. My dealer never mentioned it.

    Jim

    Glad to hear it worked out for you... Don't expect it to last forever though, my torque converter eventually started slipping a little bit more with age and mileage and I started popping off P039 again after about 14 months... So eventually you may have to replace the torque converter...

    I'm not surprised the dealer didn't mention it... I'm thinking they were probably going to try to sell you a whole new transmission later on...

  9. #8
    jimusa95 is offline Cadillac Owners Member
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    Re: P039 Problem: 99% Solved by New Prom!!

    Quote Originally Posted by wake
    ... Don't expect it to last forever though, my torque converter eventually started slipping a little bit more with age and mileage and I started popping off P039 again after about 14 months... So eventually you may have to replace the torque converter...
    Thanks for the heads up -- When the time comes, I'll know what to expect.

    Jim

  10. #9
    chrismaz is offline Cadillac Owners Member
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    Re: P039 – VCC Lockup Problem: Read Archives, Still Have Questions

    Hi, I'm french just arrived in California, and I bought my dream car
    an eldorado cadillac 95, I paid the car $4500; 95000 miles , nice body,
    but after several weeks, I have a service engine soon especially when I
    drive in the mountains. I found the code P039( torque converter) Today
    I went to Cadillac for a diagnostic, they told me I have to replace the
    transmission , it cost $4200!. I'm not be able to spend this amount.
    The transmission seems to be good, except the service engine soon
    sometimes and a low rpm sometimes with a ping noise. The oil is red/pink.DO
    you think it's serious to say I have to change the transmission, or it's
    because I'm just a naive french guy just in my first Cadillac dealer!!
    ?Thank you for your help."

  11. #10
    1997BlackETC's Avatar
    1997BlackETC is offline Cadillac Owners Connoisseur
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    Re: P039 – VCC Lockup Problem: Read Archives, Still Have Questions

    Quote Originally Posted by chrismaz View Post
    Hi, I'm french just arrived in California, and I bought my dream car
    an eldorado cadillac 95, I paid the car $4500; 95000 miles , nice body,
    but after several weeks, I have a service engine soon especially when I
    drive in the mountains. I found the code P039( torque converter) Today
    I went to Cadillac for a diagnostic, they told me I have to replace the
    transmission , it cost $4200!. I'm not be able to spend this amount.
    The transmission seems to be good, except the service engine soon
    sometimes and a low rpm sometimes with a ping noise. The oil is red/pink.DO
    you think it's serious to say I have to change the transmission, or it's
    because I'm just a naive french guy just in my first Cadillac dealer!!
    ?Thank you for your help."
    I would not worry about it, I have been driving with that code for years. I put a peice of black electrical tape over the check engine light, works great. The only effect of having this problem is a little worse gas mileage. I looked into getting the revised chip, but could not find out anything about it from the dealer, the car is a 1993 deville, they looked at me like I was nuts.

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