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The check engine light and PO39 (a VCC torque converter) code on my 94 Eldo appear when I take a certain route leaving my house in the morning. I can drive for weeks other than that and no problem. In researching I learned that a revised calibration Prom was released to correct this problem. I did a test suggested by bbobynsky on the now defunct GM forums to see if the VCC is actually functioning and it is so now my question is has anyone here done this replacement? Is it hard to find where the prom is to be placed? I certainly don't want to cause more damage than I cure. It's really just an annoyance since the code can be easily erased but here in N.J. where they haven't found a new regulation they didn't like they are leaning toward turning down any car in their inspectin stations that have a check engine light or code on and making you take it to an "APPROVED SHOP" for repair. Please, any guidance would be great.
 

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Successful replacement prom... somewhat!

Yes, I did replace this with the updated prom on my 93 eldorado a few months back. My symptoms were exacly what you had described, only mine was actually popping up a P039 code on occaision even cruising through town once it was warmed up. I was getting sick of constantly checking and clearing the code. :mad:

I ordered the part from GM parts direct.com, and I believe it was about $46 total shipped directly to me. Not too difficult to replace, the PCM is under the glove box, behind the kick-panel. You need remove the door threshold trim piece also. Once the K-P is removed, you have to remove 1-2 screws holding the PCM up to the chassis. Carefully slide the unit off the mounting pins, you may have to pull back the carpeting to have a little more room.

Be aware that you don't want any static electicity or magnets near the proms, because this will destroy it. There is a small plastic clip on one end of the PROM which retains it as I recall. You flip that back and carefully pop the prom off the PCM. Install is reverse order of course. I took mine out for a test drive when the PCM was still hanging there, just to be sure it worked before buttoning it up. ;)

Now, untill just recently I hadn't had a P039 code since. Suddenly one day I had it come up, on that first slight hill on my morning commute. It has 5-6 times since over the last few weeks, but nothing like it used to. So I'm not sure why it was only a limmited sucess. I am also having the famous P056 (trans input speed sensor error) come up quite regularly, especially when I am hammering the pedal to the medal! :D Maybe it is related to that? Maybe someone else has an idea?

Here is a helpful link (where I originally got most of my info) to help you out on the P039 code... :cool:

http://www.caddyinfo.com/howtop039.htm
 

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Discussion Starter #3
Thanks sprucegoose. I was begining to wonder if anyone else here had tried it. I had found the site that you suggested but it was lacking the info about where to find the prom and anything about the difficulty in replaceing it. You have answered that. It probably is in the same place on my 94. Thanks again!
 

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No problem, glad to help! :bouncy: I'm pretty sure that it would be almost identical...

I am actually very surprised and happy that my trans. is doing as well as it is. When I bought the car in June with 156K on it, I found the trans to be severly overfilled. I sumped out almost 2 qts. before I got it down to the correct fluid level! I also found the carpet on the drivers side to be saturated with trans fluid. I think it had been blowing out of an overflow somewhere and seeping in near the column opening in the firewall! How weird is that!? :disappoin Talked to the previous owner about that and he stated "Well, I kind of remember Jiffy-Lube saying something about that they topped off the fluid last time" That was apparently about 6 mo. earlier... :devil: Never, ever let JL top off your trans. My dad had the same thing happen to his van, they overfilled the oil AND the trans fluid! :mad:

I am going to do my first trans. fluid replacement soon, hopefully no surprises there in the pan. Quite a different trans, the filter is really not regularly serviced, and $27 for just the gasket. And that was with a big discount! Good luck with your PROM replacement! ;)

Dave
 
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