: Po39

08-31-05, 08:47 PM
What am i suppose to do with PO39. How do i fix it

08-31-05, 09:06 PM
Here is some info for you about a possible fix:
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...


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

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

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

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

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

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.

Hope this helps

04-08-06, 07:08 PM
Good Thing I Looked At This, Because I Am Having The Same Problem And The Same Code In My History. I Will Look Into This.


04-09-06, 09:43 PM
I used to own a 1994 Deville Concours, and it too had the P039 TCC problem. The new PROM fixed it! The hardest part if getting the computer out from under the dash.

04-10-06, 05:43 PM
Hey where can i get that prom update from?

04-29-06, 07:55 PM
I totally forgot about this thread, Thank adission ii. I had the same symtoms. Where can I get the "prom". What does prom stand for? Sorry but it a stupid question.

04-29-06, 10:37 PM
I totally forgot about this thread, Thank adission ii. I had the same symtoms. Where can I get the "prom". What does prom stand for? Sorry but it a stupid question.

Any GM dealer can get it for you using the part number from the TSB in the above post, or online from www.gmotors.com or www.gmpartsdirect.com

Programmable Read Only Memory

07-24-06, 03:55 PM
Computer sets Code P039 - "Extensive slippage", when some conditions occurs. As I understand, ideal slippage speed should be around zero when TCC is locked. Computer takes in account load (accelerate angle) and engine speed acceleration. If slippage speed (difference between TCC in and out RPMs) more than, let say 130 (I don't know exactly) and it occurs more than 5 sec, computer sets the code.
I don't think that with new software computer unlocks TCC if slippage is high. I assume that Cadillac changed slippage criteria in a new PROM software to the higher number (so it just allows to have higher slippage). It doesn't change anything, except of you're not getting code P039 so often or not at all.
If your transmission is on a way down, changing PROM to not to get code anymore it's like cover message with a tape. Extensive slippage leads to TCC to fail.