trailer towing

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Oct 6, 2002 | 04:50 PM

tiwood

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New User

Joined: Jun 2001

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trailer towing

I have a 99 3/4 ton crew cab diesel, I have pulled a 32ft 8000lb trailer with no problem ( overdrive and cruise on). I just purchased a 27ft 5th wheel that is only 6600lb and the transmition now does not want to shift to overdrive after climbing a hill. Any ideas???

Oct 6, 2002 | 06:13 PM

Aaron S

Senior User

Joined: May 2002

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From: Kalispell, MT

trailer towing

I would guess the profile of your 5er is making the truck work a little harder even though it weighs less. The transmission is probably getting hot and I think there is some temp protection that won't allow it to shift into OD because OD will just heat it up more. This is just a guess though.
Aaron.

2001 F250 PSD 6-SPD 4x4 SCMT Banks Monster Exhaust EGT, Boost, Oil Pressure, Oil Temp/Trans Temp Gauges

Oct 7, 2002 | 08:22 PM

tiwood

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Joined: Jun 2001

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trailer towing

Thanks for your reply. The 5th wheel I now have is not one of the tall campers, it is no taller than the old 32ft. bumper pull. so I don't think wind resistance is the problem. I read somewhere that when you plug in the trailer that the truck computer makes adjustments with the transmition shift pattern for better towing. I don't know if this is true or not. Has anyone else heard this?

Oct 8, 2002 | 09:22 AM

Mark Kovalsky

Frmr Ford Trans Engr

Joined: Aug 1999

Posts: 24,696

Likes: 2,617

From: SE Florida

trailer towing

>I read somewhere that when you plug in the trailer
>that the truck computer makes adjustments with the
>transmition shift pattern for better towing. I don't know if
>this is true or not.

It isn't true. The only way the the computer "knows" a trailer is back there is that you have to use more pedal to get the truck moving.

There is a TSB on the lack of the 3-4 shift while towing with the '99 trucks. The TSB calls for a PCM reflash with a code that won't do this. If you are out of the 3/36 warranty the cost is probably on you.

Oct 8, 2002 | 06:48 PM

johnsdiesel

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Joined: Aug 2002

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From: Denton,TX

trailer towing

I don't know if this has anything to do with your problem, but your pin weight is a lot higher with a fifth wheel. Even with your lighter trailer, there is more weight sitting on your truck.

Oct 9, 2002 | 08:23 PM

tiwood

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Joined: Jun 2001

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trailer towing

Thanks for the info. I looked in the service bulletins and didn't fine any on transmitions when towing. Do you know the bulletin number? Thanks for the help

Oct 10, 2002 | 01:27 AM

BlueOvalBoy

Senior User

Joined: Jun 2002

Posts: 279

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From: Brighton, Colorado

trailer towing

99-16-9.
I had it done 3 years ago. Made the truck shift better through all of the ranges. It would kick out of cruise and not go back in.

99.5 Ford Super Duty F-250 XLT 4x4. S/C L.W.B. PSD Auto loaded.
4 in. Pro-Comp lift. 35 x 12.5 x 16.5 BFG AT/KO. Weld SSII 16.5 x 9.75. Rancho 9000's Dual Front.
Warn M12000 in Semi-hidden mount. Astro-start Supreme 3001.