How to determine if "YOUR CRD HAS HAD F37 PREFORMED"

Joe Romas · **Posted:** Wed Feb 03, 2010 10:40 am

I have put a thread in the tech section for all new new owners that want to find out if they have the "holy grail" TCM :jester:

I've also put in some history about the CRD's torque converter and the F37 flash :JEEPIN:

Please note the Tech section was started by GMTD to contain usefull tech information so put replies here...

ac5501 · **Posted:** Wed Feb 03, 2010 12:47 pm

Quote:

If your RPM’s are 1900 that means you have had the F37 flash :dead:

At this point if you go up to around 62-64 it will shift again and the RPM’s will drop. You can slow back down to just above 59 MPH and you’ll see about 1700. Any slower it will down shift.

Ok, somebody please tell me what I have cuz I am confused.

I can take my Jeep up to 60mph and it will not shift (rpms 1900 - F37?). It will stay there indefinitely until I accelerate to just past 60mph (hardly ever makes it to 61) then it shifts. At this point I can slow all the way down to as low as 56-57 (Non F37?) before it will downshift.

I wonder if Chrysler updated the TCM flash related to the F37 at some point so that there may be a 3rd TCM revision out there?

This is both before and after the GDE tune. An interesting note regarding the GDE... Before the GDE If I got down to 56 in lockup, it would stay there. I can still do this with the GDE, but (many times) after about 15 20 seconds it will downshift into 4th. I figure its related to what they do to eliminate the shudder.

stoutdog · **Posted:** Wed Feb 03, 2010 12:50 pm

See I'm going to have to disagree with Joe and say that your physical speed (GPS reading) is more important that what your miscalibrated speedometer says.

non-F37 = 58 mph GPS shift
F37 = 61 mph GPS shift

BlackLibertyCRD · **Posted:** Wed Feb 03, 2010 1:08 pm

X2 what stoutdog says. Differents between 2005 and 2006 is only 3 MPH not 5 or 6 MPH like the miscalibrated speedometer says. Not a big issue to me for I rather the engine not to lug.

Rich · **Posted:** Wed Feb 03, 2010 10:17 pm

ac5501 wrote:

Quote:

If your RPM’s are 1900 that means you have had the F37 flash :dead:

At this point if you go up to around 62-64 it will shift again and the RPM’s will drop. You can slow back down to just above 59 MPH and you’ll see about 1700. Any slower it will down shift.

Ok, somebody please tell me what I have cuz I am confused.

I can take my Jeep up to 60mph and it will not shift (rpms 1900 - F37?). It will stay there indefinitely until I accelerate to just past 60mph (hardly ever makes it to 61) then it shifts. At this point I can slow all the way down to as low as 56-57 (Non F37?) before it will downshift.

I wonder if Chrysler updated the TCM flash related to the F37 at some point so that there may be a 3rd TCM revision out there?

This is both before and after the GDE tune. An interesting note regarding the GDE... Before the GDE If I got down to 56 in lockup, it would stay there. I can still do this with the GDE, but (many times) after about 15 20 seconds it will downshift into 4th. I figure its related to what they do to eliminate the shudder.

http://www.youtube.com/watch?v=FKCqfML5V2Y

Instructions;
1. With your engine and trans at operating temp, accelerate at a normal pace from a stop to 60mph on the speedo. It does NOT matter if your speedo is accurate or not, the TCM uses the same speed signal as the ECU/Gauges for shift points.
2. Once you reach 60mph, hold the speed and look at your tachometer.
- If tachometer is at 1700-1800rpm - NOT F37
- If tachometer is at 1900+ - IS F37
This video shows a TCM WITHOUT the F37. 4-5 shift at 0:13 in the video at ~57mph on the speedo.

CRD Joe · **Posted:** Sun Feb 07, 2010 3:17 pm

I want my truck to shift EARLIER! Cant the GDE guys tune that? I hate this darn F37 thing.

ATXKJ · **Posted:** Sun Feb 07, 2010 4:11 pm

Well - it's encrypted -
but there are folks on the internet who laugh at encryption schemes
the problem is getting the source code into a place where the hacker could play... Don't know how to do that.

The other option that seems easier - is to mass copy a non-F37 TCM and write over the entire Memory array
I mean - you may not know what 1's and 0's you're writing - but they'd both be the same.

That seems like something GDE could do.....

warp2diesel · **Posted:** Sun Feb 07, 2010 10:52 pm

ATXKJ wrote:

Well - it's encrypted -
but there are folks on the internet who laugh at encryption schemes
the problem is getting the source code into a place where the hacker could play... Don't know how to do that.

The other option that seems easier - is to mass copy a non-F37 TCM and write over the entire Memory array
I mean - you may not know what 1's and 0's you're writing - but they'd both be the same.

That seems like something GDE could do.....

Hook your TCM up to your computer and log onto the internet. Sooner or later the hackers will crack it. :ROTFL:

Rich · **Posted:** Mon Feb 08, 2010 1:19 am

warp2diesel wrote:

Hook your TCM up to your computer and log onto the internet. Sooner or later the hackers will crack it. :ROTFL:

So the TCM uses a Micro$oft OS? :ROTFL:

How to determine if "YOUR CRD HAS HAD F37 PREFORMED"

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