Pre-F37 Flash

AZScout · **Posted:** Sat Jan 06, 2007 2:38 pm

From what I understand, the current flash update on the F37 recall was offered prior to the full recall. Is it the reflash that reduces the torge or the actual hardware change that does it? The reason I ask is I believe I recieved the flash back in late September of last year. At that time there was no notice of reduced torque. If this is the case, then I want a new PCM as this was not told to me prior to the flash. Also, is it possible to get a PCM without all the flashes on it. There is a noticable decrease in my power but I didnt notice due to the SP chip. I've taken the chip off in anticipation of the full F37 recall and have noticed a loss of power, even from stock. So my questions are:

1. Was the flash offered prior to the F37 recall?
2. Is the reflash the cause of the reduced torque?
3. Can I get a new PCM without flashes (completely stock)?

P.S. After the flash in September, the shifting was a lot smoother, however, I was always sitting at 2500RPM whereas before it shifted at 2100RPM.

Thanks!

Goglio704 · **Posted:** Sat Jan 06, 2007 2:59 pm

If you read the text of the F37 recall instructions, it indicates, to me at least, that the correct software may already be in place. To me, that means the programming came out prior to the F37. F31 was the previous reflash. I think that several who had the F31 have posted the F37 was a hardware only event for them. Mixed reports on the effect of the F31 on power. The ECU must be programmed with the VIN in order to work. I don't know if this is true for the TCU as well. I would be surprised if a dealer would program a CU of either sort with anything other than the latest release.

Legal Disclaimer: The information is part speculation and part fact. Speculation is accompanied by phrases such as:
to me, I think, I believe, or I don't know if it is true. If you are reading this, I think you have good eyes.

AZScout · **Posted:** Sat Jan 06, 2007 3:02 pm

Thanks Matt...

Do you know exactly what computer is reflashed? Is it the ECU, PCM, BCM, or something else?

I thought it was the PCM and called Jeep for the cost... $540.00

Thanks again!

Goglio704 · **Posted:** Sat Jan 06, 2007 3:05 pm

Pretty sure the F37 flashes both the engine CU and the trans CU. Only flash I can think of on the body CU is the one on the 2006 models which were draining the batteries.

AZScout · **Posted:** Sat Jan 06, 2007 3:12 pm

I think you are right. Here is a quote from the actuual recall notice.

"DaimlerChrysler will repair your vehicle free of charge (parts and labor). To do
this, your dealer will replace the torque converter and reprogram the engine and
transmission control modules. The repair involves a small reduction in engine torque
to enhance torque converter and transmission durability. The work will take about 5½
hours to complete. If testing indicates the transmission has been damaged, another
hour will be required. However, additional time may be necessary depending on how
dealer appointments are scheduled and processed. "

Does this mean I need two computers to bring this thing completely back to stock?

RFCRD · **Posted:** Sat Jan 06, 2007 3:32 pm

AZScout wrote:

From what I understand, the current flash update on the F37 recall was offered prior to the full recall. Is it the reflash that reduces the torge or the actual hardware change that does it? The reason I ask is I believe I recieved the flash back in late September of last year. At that time there was no notice of reduced torque. If this is the case, then I want a new PCM as this was not told to me prior to the flash. Also, is it possible to get a PCM without all the flashes on it. There is a noticable decrease in my power but I didnt notice due to the SP chip. I've taken the chip off in anticipation of the full F37 recall and have noticed a loss of power, even from stock. So my questions are:

1. Was the flash offered prior to the F37 recall?
2. Is the reflash the cause of the reduced torque?
3. Can I get a new PCM without flashes (completely stock)?

P.S. After the flash in September, the shifting was a lot smoother, however, I was always sitting at 2500RPM whereas before it shifted at 2100RPM.

Thanks!

The torque reduction is controlled entirely with software. With most systems of this type, the TCM (transmission control module) takes a primary role in telling the ECM (engine control module) how to run the engine. You can not buy a TCM or ECM with the original software unless you find a wreck that was never reflashed. DC control access to the modules and they are flashed live (on-line) to the most current software available from DC as their computer reads and updates as necessary. You don't get a choice.

Here is the word from my dealer on the software: Before the F37 recall, the last comprehensive TSB issued was 18-023-06 which updated software for both the TCM and ECM to the latest revision. Recall F31 updated TCM software only to correct a communications glitch embedded in the previous version TSB 18-009-06 or 18-008-06. So it is possible to see an '05 with the original version or serviced under TSB 18-015-05, TSB 18-009-06, or TSB 18-023-06. I had the F31 done against 18-009-06 in the ECM, 18-023-06 in the TCM and they had to flash both again for the F37.

On your RPM comment, they are working with multiple variables. Common to most diesels of this type, horsepower climbs and torque drops off sharply above a certain RPM level. They are playing a game with the performance curve. I believe they raised the shiftpoint (RPM) so it's past the torque peak when it grabs the next gear on the upshifts. They set the upshift higher in the performance curve and control the torque potential on the upshift. They also independently set the downshifts lower in the curve to reduce gear hunting. BTW, some Allisons have a switch where you can select between two shift programs. This version would be considered being in "performance" mode as opposed to "economy" mode. It will also adversly effect your fuel mileage in stop & go driving.

Goglio704 · **Posted:** Sat Jan 06, 2007 3:35 pm

If I were you, I would start with the TCU. I think that is where the objectional behavior is coming from, but I certainly can't prove that. As I said earlier though, I doubt you'll be able to get the software you want unless you know somebody at a dealership. Even that might not work if DC makes them destroy old files. You might want to check your boost sensor before you do anything. There is a whole thread about it.

AZScout · **Posted:** Sat Jan 06, 2007 4:38 pm

Ok...seems like a new computer is out of the question. I was told by Jeep that the computer has some information on it but to complete the hookup more information is downloaded through DC according to VIN #. If that is true, then outside of getting computers from a wreck we are stuck with the flash.

If that is true, then does this mean that no matter what we do (getting a new TC and TQ, trans-go shift kit, or Inmotion tuner) we will never regain the power loss that F37 entails?

Thanks!

Goglio704 · **Posted:** Sat Jan 06, 2007 4:55 pm

It didn't go anywhere, but I started a thread a while back speculating about the feasability of non dealer flashes. The gist of it was that the equipment is available outside the DC system, but it is grossly expensive. The files are by subscription I think. That or the kind of thing you mentioned may well be the only options.

TDI4BY · **Joined:** Sun Apr 02, 2006 11:56 pm **Posts:** 644

My Jeep has never had any of the flashes and everything is perfect. Maybe I can get rich selling it to the highest bidder. :lol:

Pre-F37 Flash

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