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P039 Solved  Jim Wakefield Time: Wed, 13-Mar-2002 08:26:45

Well, it's been a week since I posted about the TSB for a new MemCal and the problems I was experiencing with the P039 TCC/VCC transmission code...

After 1 week of MANY short and a few long trips (I've been on vacation from work) I'm happy to report that I have not yet been able to set the P039 code again since installing the new PROM...

A little background on my car, experiencing intermittent P039 code mostly on cold starts, usually about once every 10 trips...  I figured out that in my situation it was during low RPM/high torque situations (slight incline/grade)...  Usually the code would set when the torque converter was still locked but the powertrain had a larger demand placed on it such as climbing slight grades...

I found a TSB for 93-95 Caddys with the "Y" code motor that listed a revised memcal PROM to cure the problem that I've seen many on this board are experiencing...  Since I couldn't find
anything wrong physically with the trans after a couple weeks of troubleshooting, I decided to give the updated PROM a chance ($50)...

Now, even when I try I am unable to create the conditions from before to set the P039 code...  Previously I was able most of the time to set the code when I purposefully drove the car a
certain way (mostly very light throttle up an incline, trying to keep the TCC engaged)...

My impressions of drivability differences...  Well, I'm happier with the PCM's management of the TCC now...  One thing I've never liked about GM since changing to 4spd AOD transmissions
has been the delayed disengagement of the TCC under light throttle conditions...  This new PROM seems to unlock the TCC at the slightest increase in throttle position, almost like a
slight downshift when I ease into the throttle...  It seems IMO, the perfect calibration for my style of driving for both locking up and unlocking the TCC...

So for those of you out there that might be experiencing the same problem as I was, it might be worth a shot after you've exhausted other troubleshooting options and the transmission is
in good working order...

Here is a repost of the TSB from last week...

[START]

TSB# 87-65-17
DTC P039 Set When Driving Up Slight Grade After Cold Start

Subject:
DTC P039 Set When Driving Up Slight Grade After Cold Start
(Diagnose/Install New PCM)

Models:
1993-95 Cadillac Eldorado, Seville 1994-95 Cadillac Concours,
Deville With 4.6L Engine (Vin Y - RPO LD8)

Condition:
DTC P039, Torque Converter Clutch Engagment, May Set When
Driving Up A Slight Grade After A Cold Start.

Correction:
A PCM Calibration Enhancement Has Been Released For The Above
Listed Vehicles.  If A Vehicle Is Encountered With This
Condition, And All Of The Diagnostic Procedures Listed In The
Service Manual Have Been Performed With No Resulting Correction,
Then Update The Vehicle With The Applicable Calibration Listed
Below.

Parts Information:
Part Number Description 16266755 1993 PCM PROM, 16266762 1994
PCM PROM, 16266767 1995 PCM PROM

Parts Are Expected To Be Available From GMSPO On June 1, 1998.

Jim
94 Eldorado ESC, 96 Corvette

 

 

PO39 FIXED w/PROM!! BIG NEWS TO MANY Double H  
Jim's post about changing the chip proved to be extremely valuable, to me.   Some info - 1994 Concours bought used last summer with over 100k miles.  Nice seller, car was well-mainained mechanically, not so cosmetically.  The aesthetics, the mileage, but also the "SERVICE ENGINE SOON" telletale going off regularly all contributed to a low purchase price.  I addressed the aesthetics and have done more maintenance, but that telltale was going off for....40,000 miles
now!  Yes, I've figured out ways to try to 'go around' setting it off, but frankly its a nuisance.  This PO39 "TCC ENGAGEMENT PROBLEM" code is VERY common in 1994 Concours' - I've personally discovered a half dozen Concours' with this code going off regularly, of mileages varying from under 50k to over 100k.    I've tried all the suggestions Al had, to no avail.  The only fix
as I saw it is a trans-rebuild costing $1500+.  Given that the car runs great otherwise, this is not an option I was considering at this time.

Along comes JIM WAKEFIELD and his persistence and enthusiasm, to arrest this problem in his car (1994 Eldorado - same drivetrain).    He and his neighbor discovered a TSB never previously discussed here, about a replacement PROM for the computer that will address this matter.  Scroll down - Jim had success in curing this deficiency with just a chip change as noted in the TSB.  I figured I'd give him a solid week just to be sure it had been addressed and apparently Jim is still smiling.

I ordered the chip from my buddy at the local Chevy dealer parts counter.  I was reluctant because upon looking up my VIN, a different chip was coming up then the one that Jim Wakefield noted
in that particular TSB.  BUT, when we looked up that specific chip number - it came back that it would work in my year/model of Cadillac - although along with the Eldorado and the Seville.  This
grouping of notably different cars, all on the same chip - had me concerned.  My Concours weighs a bit more than Jim's Eldorado; the idea that both cars would be operated under the same (PROM)
parameters was not credible to me.  Still, at $44 total purchase price I had to take a shot with this.

Got the new chip home yesterday and engaged installation Friday afternoon.  On the drive home from the dealer, I deliberately tried to set the code and I don't know if its coming easier or I'm
just good at it - but I set it off my very first try so its going off easy.  Got home - first off - the chip has a notably different Letter Code than the one it would replace.   The old chip in the
car reads BKFZ, and even my 1994 Eldorado I had years ago had a BK-- chip.  This new chip starts with a "C".  So I knew it was a whole series off from the one it was replacing, but like I said -
I was willing to take this $44 chance.  Installed chip via shop manual instructions (ground yourself to avoid static).   Go to start the car - pretty much expecting it won't even start...it
started!  Expecting "Monitored Functions" problems right after start-up....nothing!  Ran the codes - only the codes because I changed a chip, as expected according to shop manual....so no
codes!   Took it out....couldn't set the code!!!!!!!!!!  Was out last night in various driving conditions, most of which would set the code if I didn't work at it to 'drive around' it - NO CODE AT
ALL ALL NIGHT.

This is huge news to me.  I love this car, and this was one 'unaddressable' thing that really bugged me.  And dare I say this out loud?   A deficiency that has plagued my car for some
40,000 MILES, I think ITS FIXED

HUGE THANKS TO JIM WAKEFIELD AND HIS NEIGHBOR.  You are going
to make a number of Cadillac enthusiasts (who have this problem), a lot happier.   As for me, I'm very grateful to you, for this.

Best,
Double H