bulldogrider Posted July 10, 2019 Share Posted July 10, 2019 I bought myself a 2015 cxu highway tractor day cab then I took the 5th wheel off and converted the truck to a gravel truck with a dump box, I used the 5th wheel air line to operate the tailgate everything went as planned, the only problem I have that when I need to spread a load of gravel I raise the box half way up and I start rolling the truck before I open the tailgate but the 5th wheel switch on the dash won’t operate the tailgate in moving mode it’s the way it’s designed for the 5th wheel. My question is there anyway the make it operate In moving mode, although when the truck is stopped it opens but soon I start moving it closes automatically any help is much appreciated. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/58058-5th-wheel-solenoid/ Share on other sites More sharing options...
bulldogrider Posted July 12, 2019 Author Share Posted July 12, 2019 Come on anyone guys Quote Link to comment https://www.bigmacktrucks.com/topic/58058-5th-wheel-solenoid/#findComment-427592 Share on other sites More sharing options...
Quickfarms Posted July 12, 2019 Share Posted July 12, 2019 Is it not working during the application of the service or parking brake or both Quote Link to comment https://www.bigmacktrucks.com/topic/58058-5th-wheel-solenoid/#findComment-427593 Share on other sites More sharing options...
41chevy Posted July 12, 2019 Share Posted July 12, 2019 (edited) The switch it is most likely run through the VCU or ECU and tied to a switch on the brakes. Maybe try it with the brake pedal slightly depressed? Edited July 12, 2019 by 41chevy Quote "OPERTUNITY IS MISSED BY MOST PEOPLE BECAUSE IT IS DRESSED IN OVERALLS AND LOOKS LIKE WORK" Thomas Edison “Life’s journey is not to arrive at the grave safely, in a well preserved body, but rather to skid in sideways, totally worn out, shouting ‘Holy shit, what a ride!’” P.T.CHESHIRE Link to comment https://www.bigmacktrucks.com/topic/58058-5th-wheel-solenoid/#findComment-427594 Share on other sites More sharing options...
Popular Post j hancock Posted July 12, 2019 Popular Post Share Posted July 12, 2019 Replumb the gate air directly to your air tank with a separate old style air switch. No electronics, no nothing. Works when you want it to work. 3 Quote JimIt doesn't cost anything to pay attention. Link to comment https://www.bigmacktrucks.com/topic/58058-5th-wheel-solenoid/#findComment-427618 Share on other sites More sharing options...
bulldogrider Posted July 12, 2019 Author Share Posted July 12, 2019 8 minutes ago, j hancock said: Replumb the gate air directly to your air tank with a separate old style air switch. No electronics, no nothing. Works when you want it to work. True, but I’m trying to save some cost and work since that air line is already there. Quote Link to comment https://www.bigmacktrucks.com/topic/58058-5th-wheel-solenoid/#findComment-427619 Share on other sites More sharing options...
bulldogrider Posted July 12, 2019 Author Share Posted July 12, 2019 9 hours ago, 41chevy said: The switch it is most likely run through the VCU or ECU and tied to a switch on the brakes. Maybe try it with the brake pedal slightly depressed? That’s what I thought I will try it and let you know. If it’s running through ecm I should be able to reprogram it with tech tool, just a thought. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/58058-5th-wheel-solenoid/#findComment-427621 Share on other sites More sharing options...
41chevy Posted July 12, 2019 Share Posted July 12, 2019 6 hours ago, bulldogrider said: That’s what I thought I will try it and let you know. If it’s running through ecm I should be able to reprogram it with tech tool, just a thought. No the circuit is in the controllers and no easily bypassed. Pull the switch and use a Meter check power to the switch with it off and engaged. I am taking a leap of faith that the computer wire may be less the 12 volts probably around 5 volts . You may be able to run a new fused power line to the switch and bypass the ECU/ / VCU. Quote "OPERTUNITY IS MISSED BY MOST PEOPLE BECAUSE IT IS DRESSED IN OVERALLS AND LOOKS LIKE WORK" Thomas Edison “Life’s journey is not to arrive at the grave safely, in a well preserved body, but rather to skid in sideways, totally worn out, shouting ‘Holy shit, what a ride!’” P.T.CHESHIRE Link to comment https://www.bigmacktrucks.com/topic/58058-5th-wheel-solenoid/#findComment-427634 Share on other sites More sharing options...
Mack Technician Posted July 14, 2019 Share Posted July 14, 2019 It’s a safety feature to keep you from running around with a free-sliding 5th wheel. Safety is not negotiable. Unlikely you can PTT that away any more than a seatbelt warning, speed relative auto diff-lock disengage or trying to turn off your ABS. I’d do what Jim Hancock recommended. Minimal cost, minimal work involved. You start trying to out think R2D2.....R2 usually wins. Recently found my van won’t start if I pulled the ABS fuse. Don’t like ABS certain times of the year. However, if it’s running, you can pull the ABS fuse. So now I can put in a momentary switch to get the van started (through the start cycle) and release the switch.....which disconnects the circuit for ABS....not going to do it, but I could. Doesn’t pay to play...... Safety engineer wins his little operator control game. Quote Link to comment https://www.bigmacktrucks.com/topic/58058-5th-wheel-solenoid/#findComment-427816 Share on other sites More sharing options...
MackTech Posted November 17, 2019 Share Posted November 17, 2019 Just saw this post. The 5th wheel solenoid is run through the VECU. You could switch the plug behind the switch with the neutral control, but you'd have to switch the wiring in the connector coming from the solenoid to the connector in the mono harness. I don't know where you'd have to repin it to though. Neutral control does not go through the VECU and is a standard connector on the cab harness. Quote Link to comment https://www.bigmacktrucks.com/topic/58058-5th-wheel-solenoid/#findComment-436045 Share on other sites More sharing options...
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