2008 GT500 - cruise control drops out after auto swap

[Mainn]

Hi everyone,

I can?t get cruise to work properly after a 4R70w swap. It works perfectly in 3rd, which is 1:1 like the TR6060?s 4th, but 4th (which has a 0.70 ratio) drops out whenever the car pulls out of the throttle, i.e going downhill on the freeway.
I?ve read of other 05-14 GT?s having this problem when swapping from the TR3650 or MT82 to a T56 but no one posted a solution other than ?it?s in the tune?. Of course, 2011+ cars use a different PCM as well.

I have tried setting the gear ratios correctly, changed the load switch to 1 so the car assumes it?s in drive, both with no luck. I noticed 2007-2009 strategies don?t have min/max for gear ratios like 2010+ do (which I?ve read can fix similar issues on those 2011+ cars). Has anyone tried flashing a 2010 GT500 strategy on a 2008 GT500 PCM?

If anyone has any suggestions on how to get this working, that would be fantastic.

Thanks in advance!

[veeefour]

post a file

[Mainn]

Attached. Thanks!!

Matched for TVS 4.hpt

[B E N]

I have the same problem in a 2006 GT, original TR3650 car swapped to TR6060: cruise works fine in every gear except 5th, it seems to be a known problem. I'm interested to see if anyone has solved it.

[veeefour]

Well it may think its in 5th or higher so try to set the higher gears the same as 4th. There is no sensor to tell which gear its in, its inferred.

[Mainn]

Well it may think its in 5th or higher so try to set the higher gears the same as 4th. There is no sensor to tell which gear its in, its inferred.

So set 5th and 6th to 0.70? I have a funny feeling I’ve tried that in the past but I’ll give it another go.

[Mainn]

Does anyone have a 2010 GT500 PCM pinout diagram by any chance? If the PCM pinouts match between the ‘08 and the ‘10 I might try flashing a 2010 strategy onto my PCM (if this is possible) and see how that goes.

[rockystock]

I had the same problem with a 2006 V6 (Spanish Oak PCM) after a gear swap and recalibrating the speedometer - the cruise control would shut off when going from coasting downhill to starting back uphill, and when going from uphill to coasting at the top and heading back downhill.

I'm pretty sure the problem began after changing [ECM] 9050 - Final Drive Ratio. You might try setting it back to the original stock value and calibrate the speedo by adjusting [ECM] 5001 - VSS Pulses per Rev - Trans. FWIW, I think [ECM] 5001 is the only parameter that affects the speedometer reading on that '06 V6 OS.

You might also try resetting all speedo and gear ratio parameters back to the original setup and see if the problem goes away, then maybe change only one parameter at a time until everything runs like it should.

[Mainn]

I had the same problem with a 2006 V6 (Spanish Oak PCM) after a gear swap and recalibrating the speedometer - the cruise control would shut off when going from coasting downhill to starting back uphill, and when going from uphill to coasting at the top and heading back downhill.

I'm pretty sure the problem began after changing [ECM] 9050 - Final Drive Ratio. You might try setting it back to the original stock value and calibrate the speedo by adjusting [ECM] 5001 - VSS Pulses per Rev - Trans. FWIW, I think [ECM] 5001 is the only parameter that affects the speedometer reading on that '06 V6 OS.

You might also try resetting all speedo and gear ratio parameters back to the original setup and see if the problem goes away, then maybe change only one parameter at a time until everything runs like it should.

Hmm, this is interesting. So it must definitely be due to a mismatch in rpm & speed that the PCM senses.
I have the final drive ratio stock, VSS pulses set to 6 for the 4R70w. I have tried stock gear ratio and speedo parameters but had the same issue unfortunately.

I tried flashing a 2010 GT500 file on to the car, and then reading it back as per strategy swap instructions. It had the same VIN as the original file, rather than my car's. Maybe this strategy swap method only works on Copperhead PCMs?
In addition, the car wouldn't crank (presumably due to the mismatched VIN), and it had a traction control fault with key on engine off.

[B E N]

Well it may think its in 5th or higher so try to set the higher gears the same as 4th. There is no sensor to tell which gear its in, its inferred.

I tried this yesterday, thanks for the suggestion. It did not change the lack of cruise in 5th, it's not even trying. Whatever wizardry ford used to tell which gear these are in may be getting confused. I think the AOD swap from the OP is even worse because the computer is looking specifically for the shift detent signal out of the trans harness.

[Mainn]

I tried this yesterday, thanks for the suggestion. It did not change the lack of cruise in 5th, it's not even trying. Whatever wizardry ford used to tell which gear these are in may be getting confused. I think the AOD swap from the OP is even worse because the computer is looking specifically for the shift detent signal out of the trans harness.

Thanks for testing this too - it helps to have someone else providing their data and trying to figure it out with me!
Your 5th is a 0.80 ratio, and the TR3650 had a 1.00 4th and 0.67 5th if my Googling is correct. So your 5th is right in the middle of what used to be 4th and 5th on your old transmission. This is most likely why it doesn’t even work at all on your car, because it’s too far away from your stock 4th or 5th - whereas on mine it is close enough to activate (0.70 4th new vs 0.63 6th old) but drops out regularly. I’m starting to think cruise follows values for gear ratios that we don’t get to see in the calibration, or they are stored in the VID block or something.

Frustrating issue.

[B E N]

Sometimes these will drop out of cruise or act wonky under cruise if your torque tables are too far off, have you checked to see if you have high torque errors in the area where cruise is dropping out?

[JuiceNA]

I used to get intermittent cruise drop out (Gen 1,w/ Magnum XL swap). Try increasing and decreasing "number of holes" and compensate with tire revs. I belive the dorp out is due to the ratio being on the very edge of the 'window'.

Ps: Cruise only works in 6th, as I have no access to min/max ratios. Cruise should work in 4th also, as it's same as mt82 5th, but it does not and I don't know why. Not apples to apples, but sure sounds very similiar.

[Mainn]

Sometimes these will drop out of cruise or act wonky under cruise if your torque tables are too far off, have you checked to see if you have high torque errors in the area where cruise is dropping out?

Good thinking - I have not, I’ll have to log and see.

I used to get intermittent cruise drop out (Gen 1,w/ Magnum XL swap). Try increasing and decreasing "number of holes" and compensate with tire revs. I belive the dorp out is due to the ratio being on the very edge of the 'window'.

Ps: Cruise only works in 6th, as I have no access to min/max ratios. Cruise should work in 4th also, as it's same as mt82 5th, but it does not and I don't know why. Not apples to apples, but sure sounds very similiar.

It does sound very similar, did you have to do the same thing to get cruise working properly in 6th? Did it work in 4th correctly prior to the changes?
Regardless, I will try this also. If OSS holes can be set to a decimal, I’ll try 6.4 and reduce revs/mile to get the speedometer accurate again - if my maths is right this should make the car think it’s in a ~0.75 gear which is close to the TR6060’s 5th of 0.80. (don’t want to go too far and prevent cruise working in 3rd). Hopefully this is close enough to allow cruise to work without dropping out. I will test and update!

[B E N]

5th is the only gear cruise doesn't work with my tr6060 swap.

[JuiceNA]

I'm out to three decimal places, lol. I wanted tire revs/mile to be as close to real world as possible. I don't want to flash just for swapping out tires of different size. I change tire size and gear ratio in the VID block, not in the tune.

[Mainn]

Well, I have the car back from the trans shop and I managed to get out on the freeway and test...

It WORKED! I had no cruise dropouts in 4th at all over the 100 mile drive through the hills I did today.
In addition, cruise still worked in 3rd perfectly also.
Setting my OSS holes to 6.4 and the gear ratio of 5th to 0.75 meant that when I was in 4th, the car thought the rpm's were only out by ~7% compared with the factory Tremec 5th, rather than ~11% with the correct number of OSS holes set. Why did I choose 7%? Because making this change meant I had to set the ratio of 4th to 1.07 - so when I was in 3rd, the car thought the rpm's were 7% out with the factory Tremec 4th. Splitting down the middle evenly was done to try and get cruise to work in BOTH gears, rather than just one.
Within 7% is obviously close enough for the PCM to not drop cruise, whereas 11% was not. I adjusted tire revs/mile from 790 to 740 to compensate for the speedometer inaccuracy.

No cruise in overdrive has been something we have lived with since the trans swap in 2013 so I am stoked.

Thank you for the suggestions everyone!

[veeefour]

Well, I have the car back from the trans shop and I managed to get out on the freeway and test...

It WORKED! I had no cruise dropouts in 4th at all over the 100 mile drive through the hills I did today.
In addition, cruise still worked in 3rd perfectly also.
Setting my OSS holes to 6.4 and the gear ratio of 5th to 0.75 meant that when I was in 4th, the car thought the rpm's were only out by ~7% compared with the factory Tremec 5th, rather than ~11% with the correct number of OSS holes set. Why did I choose 7%? Because making this change meant I had to set the ratio of 4th to 1.07 - so when I was in 3rd, the car thought the rpm's were 7% out with the factory Tremec 4th. Splitting down the middle evenly was done to try and get cruise to work in BOTH gears, rather than just one.
Within 7% is obviously close enough for the PCM to not drop cruise, whereas 11% was not. I adjusted tire revs/mile from 790 to 740 to compensate for the speedometer inaccuracy.

No cruise in overdrive has been something we have lived with since the trans swap in 2013 so I am stoked.
Thank you for the suggestions everyone!

Congrats, I knew it was something related