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Torkmonster · 05-15-2022, 03:45 PM

Hello all. I have searched threads and found several about cruise control. But I could not find anything like this.
I have a 2004 36 MD, 80K miles, 400 Cummins with Vansco's. 4 days ago I was using cruise control for 3 hours of my 4 hour drive. I stopped at a rest area. When I got back onto the highway, the cruise control would not engage. The "cruise on" light illuminated, but the cruise would not engage. I cycled the cruise power button repeatedly, the light came on and off as intended, but the system would still not engage. I stopped at the next rest area, shut down the rig for several minutes and tried again, to no avail. So I drove the last hour without cruise control. Yesterday I started the return trip and the cruise engaged as though nothing was wrong. An hour into the drive, it disengaged with my feet flat on the floor and my fingers no where near the smart wheel. All other functions of the smart wheel worked normally. Again the power light remained lit, and the system would not engage. I drove about an hour without cruise control, then we stopped to do some shopping. We returned to the rig after at least two hours and began the final leg home. Again the system worked perfectly for another hour or so, then disengaged without any warning. I completed the last half hour or so without cruise control. Today I drove it to the storage yard, (only about 20 minutes) and of course it worked perfectly. I have a simple two wire brake light switch and the output is tapped for a trailer brake controller. When I step on the brakes, the little LED illuminates on the brake controller. There is no indication that the brake switch is stuck on or ghosting since I can see the led from the drivers seat. If I tap the brake, the light turns on and off as it should. An help would be appreciated. Thank you in advance.

MrMark52 · 05-15-2022, 06:53 PM

1st - The cruise on our current or past coaches have both had issues with the Off/On/Set slide switch, acting somewhat the same way although the cruise wouldn’t engage unless I worked the slide back and forth, pressing down on the slide several times. It’s like the contacts may build some tarnish after the coach sits for a few weeks between uses.
I ended up replacing the whole system with a Rostra on our previous coach.
And now that I think I’ve figured it out on this coach, I’ll probably just deal with it.

2nd - is it possible something with your brake controller is shorting the 2 wire switch signal which then tells the cruise control to disengage? I would, if possible, attempt to disengage the brake controller and test - although that requires several 3-4 hour drive arounds to determine if that is the issue.

3rd - the signal that disengages the cruise can really be nothing more than an undetectable “blip”. On our current coach, the brake switch needs to be readjusted as even the slightest touch of the brake pedal will disengage the cruise - and probably flash the brake lights IF the duration of the “blip” was long enough for the lights to light.
And when I’m talking “blip”, I’m talking microseconds as opposed to the fact it probably takes milliseconds for the brake lights to light (in other words - too fast to be humanly possible to visually detect).

Just some thoughts.

Jeep401 · 05-16-2022, 07:26 PM

I would also suggest getting the brake controller out of the equation. It's possible that the Vansco isn't happy with the additional load of the brake controller.

Torkmonster · 05-16-2022, 07:48 PM

Thank you both. I will unplug the controller on Friday and see what happens. I don't use it anyway.

Jeep401 · 05-17-2022, 01:18 PM

There are a few threads on how to wire it around your Vansco if that turns out to be the problem. Be sure and let us know.

whalepirot · 05-18-2022, 06:42 PM

Quote:

Originally Posted by Jeep401

There are a few threads on how to wire it around your Vansco if that turns out to be the problem.

Strongly suggest this as last resort.

Better: learn some basic info about the capable and largely aproblematic VANSCO. It can be a valuable diagnostic tool, with flashing LEDs announcing a problem on a given circuit.

FWIW, I agree to bypass the brake controller early in the process.

Torkmonster · 05-22-2022, 11:44 AM

Well disconnecting the trailer brake did nothing. This time it took about an hour and a half and the cruise control disengaged without warning, would not reengage. But I have bigger problems now. See the post above. I'm stuck in Hollywood Florida with a twisted wardrobe slide.