IssueI have a 2004 Dodge Ram 2500 5.9d. Starting in 2015, when I tow my 37 Ft. Larado, the cruise control will not work. Cruise control works fine when not towing.Replaced the transmission at 275,000 miles but issue existed before the change.I normally tow with Overdrive engaged and has not been an issue before 2015.I have been to 3 shops and they are clueless.I am desperate for help as I have another long trip coming up shortly.Suggestions seems to be, Don't tow with O/D on because it overheats the transmission and causes an error. I would agree except nothing logs in the error codes on the engine computer. Thanks

I know mine wont work until the motor is up to temp. It sounds like either a sensor or ECM is failing.

Brake light switch.....Has something to do with brake light circuit cause that is what trips CC offBrake controller/brake circuit wiring in receptacle ??????CC works until you plug in umbilical cord so check connections in receptacle and trailer plug and controller harness plug under dash

Perhaps there's a clue in here:Youtube - Ram cruise

You could try the vacuum hoses I had something similar many years ago, but I don't know if newer vehicles still use vaccum for cruise control

You may be getting a tiny bit of voltage feedback due to grounds between vehicles. As old biscuit is eluding to it could be in the umbilical or the connections on the trailer.I would open both ends of the umbilical if it is a jumper and clean and tighten. The same with every connections associated with the tow lightsAre you traveling with running lights on? Do you have a charge line? Any minute amount of voltage sneaking back onto the brake light circuit even though not enough to light things up could cause it to shut off. Even check the electric brake grounds.

Cruise Control Does not work when towing 5th wheen

donn0128
Explorer II
Dec 12, 2015
I know mine wont work until the motor is up to temp. It sounds like either a sensor or ECM is failing.
Old-Biscuit
Explorer III
Dec 12, 2015
Brake light switch.....

Has something to do with brake light circuit cause that is what trips CC off

Brake controller/brake circuit wiring in receptacle ??????

CC works until you plug in umbilical cord so check connections in receptacle and trailer plug and controller harness plug under dash
2oldman
Explorer II
Dec 12, 2015
Perhaps there's a clue in here:Youtube - Ram cruise
shepstone
Explorer
Dec 12, 2015
You could try the vacuum hoses I had something similar many years ago, but I don't know if newer vehicles still use vaccum for cruise control
YC_1
Nomad
Dec 12, 2015
You may be getting a tiny bit of voltage feedback due to grounds between vehicles. As old biscuit is eluding to it could be in the umbilical or the connections on the trailer.

I would open both ends of the umbilical if it is a jumper and clean and tighten. The same with every connections associated with the tow lights

Are you traveling with running lights on? Do you have a charge line?

Any minute amount of voltage sneaking back onto the brake light circuit even though not enough to light things up could cause it to shut off.

Even check the electric brake grounds.
Me_Again
Explorer III
Dec 12, 2015
2002 got rid of the vacuum cruise control. It has to be brake light switch feedback from the trailer. Do your brake light come on steady when plugged in? Chris
12thgenusa
Explorer
Dec 12, 2015
Do you tow with the lights on? Years ago I had a dual filament tailight bulb that shorted between the tailight and brake light filaments. Cruise would work fine until I turned the lights on. Check the bulbs on your trailer.
45Ricochet
Explorer
Dec 12, 2015
I'm in the brake circuit club. Might be having a problem with the brake pedal not fully coming all the way up. My old Ram would do this sometimes. I didn't realize it until at a rest stop my brake lights were on with no driver in the seat :W
Foot under the pedal with slight pressure would correct it.
shepstone
Explorer
Dec 12, 2015
Me Again wrote:
2002 got rid of the vacuum cruise control. It has to be brake light switch feedback from the trailer. Do your brake light come on steady when plugged in? Chris

I was only a couple of years off! :)
Cummins12V98
Explorer III
Dec 13, 2015
45Ricochet wrote:
I'm in the brake circuit club. Might be having a problem with the brake pedal not fully coming all the way up. My old Ram would do this sometimes. I didn't realize it until at a rest stop my brake lights were on with no driver in the seat :W
Foot under the pedal with slight pressure would correct it.

Had that on my 98.

Tow in OD just don't lug it!