usrjcro11 Posted October 30, 2022 Share Posted October 30, 2022 When I lift switch cover and toggle switch up nothing happens. When I toggle switch down a little bit of air discharges behind the dash. How does this switch work. Bought truck about 9 months ago just now trying it. How do I go about troubleshooting? Thanks Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/ Share on other sites More sharing options...
mechohaulic Posted October 31, 2022 Share Posted October 31, 2022 if possible; may I ask what switch cover would you be referring to?see a later post discussing trailer button leak . one in the same ?? the toggle switch part has this old man scratching his head. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514080 Share on other sites More sharing options...
Joey Mack Posted October 31, 2022 Share Posted October 31, 2022 is the switch for fifth wheel slide? What is it for, send a close up picture of the switch... some of these trailer switches require the trolley handle to be applied.. jojo Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514081 Share on other sites More sharing options...
mechohaulic Posted October 31, 2022 Share Posted October 31, 2022 so possibly the phrase "toggle switch up " just refers to flipping the switch up/ down; not a movement same as raising RPMs using a rapid toggling motion Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514082 Share on other sites More sharing options...
mechohaulic Posted October 31, 2022 Share Posted October 31, 2022 up/down toggle will normally exhaust a small amount of air which is the sound in the dash. Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514083 Share on other sites More sharing options...
Joey Mack Posted October 31, 2022 Share Posted October 31, 2022 Mech, its a pretty vague question to me... I will wait for more info.. Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514084 Share on other sites More sharing options...
usrjcro11 Posted October 31, 2022 Author Share Posted October 31, 2022 Raise the cover and toggle up on this Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514085 Share on other sites More sharing options...
mechohaulic Posted October 31, 2022 Share Posted October 31, 2022 correction;; up/down can also be left/right movement referring to toggle switch. Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514086 Share on other sites More sharing options...
mechohaulic Posted October 31, 2022 Share Posted October 31, 2022 2 minutes ago, Joey Mack said: Mech, its a pretty vague question to me... I will wait for more info.. last time i heard such a vague question asked ; i made the mistake of saying "i do" . what did you mean till death due us part. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514087 Share on other sites More sharing options...
Joey Mack Posted October 31, 2022 Share Posted October 31, 2022 that is air suspension control.. it drops the air bags to hook/un-hook to a trailer... Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514088 Share on other sites More sharing options...
usrjcro11 Posted October 31, 2022 Author Share Posted October 31, 2022 Yes raising protected cover and flipping switch up. Sorry for confusion 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514089 Share on other sites More sharing options...
usrjcro11 Posted October 31, 2022 Author Share Posted October 31, 2022 My problem it is not dropping air bags. Am I suppose to do something else after flipping switch? Newbie here my 1991 Mack ch does not have airbags. Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514090 Share on other sites More sharing options...
mechohaulic Posted October 31, 2022 Share Posted October 31, 2022 that suspension valve shouldn't be connected to trailer supply valve on the tractor . many trailers pick there supply off the red line for suspension Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514091 Share on other sites More sharing options...
Joey Mack Posted October 31, 2022 Share Posted October 31, 2022 do you have air bags on the rear suspension? Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514092 Share on other sites More sharing options...
usrjcro11 Posted October 31, 2022 Author Share Posted October 31, 2022 Do not thinks it is because airbags adjust without trailer valve engaged. i do have another problems I posted that is separate from this one. Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514093 Share on other sites More sharing options...
usrjcro11 Posted October 31, 2022 Author Share Posted October 31, 2022 Yes this 1994 truck has airbags on suspension. Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514094 Share on other sites More sharing options...
mechohaulic Posted October 31, 2022 Share Posted October 31, 2022 going back and forth on your other post about the air lines to trailer. a "94 is too new for me to know its air schematic. red button out shouldn't be air coming out trailer emergency line (red) during brake application. between that issue and air bags doing nothing with the switch ;first thought is someone has lines crossed. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514095 Share on other sites More sharing options...
Joey Mack Posted October 31, 2022 Share Posted October 31, 2022 ok.... there is a leveling valve on the front drive axle.. make sure there is a supply of air to it. if not, let us know.. you can un hook the supply line after you reduce air pressure below 85 psi, then crank the truck and after 85-90 there should be air coming out of the line you un-hooked.. if not... the regulator at the tank is probably junk... also, remove the dash panel and see if the switch is an air switch or all electric.. post the results. jojo 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514096 Share on other sites More sharing options...
Joey Mack Posted October 31, 2022 Share Posted October 31, 2022 its all good Mech... he is new to this.... we'll get it for him... Keep your OLD brain handy..... He may need it... Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514097 Share on other sites More sharing options...
mechohaulic Posted October 31, 2022 Share Posted October 31, 2022 nothing happens flipping switch;; could be the arm to leveling valve broke/disconnected just hanging in "off"position. then trailer red line different issue. Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514098 Share on other sites More sharing options...
usrjcro11 Posted October 31, 2022 Author Share Posted October 31, 2022 There is a leveling valve on front drive axle. I had dash apart looking for air leaks. Truck and trailer air supply buttons have airlines coming into the back of them. No wires Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514099 Share on other sites More sharing options...
Joey Mack Posted October 31, 2022 Share Posted October 31, 2022 the air switch takes air from the tank through a regulator in a pro set-up. then sends it to the leveling valve to the 'pilot' port.. the valve dumps the air for you, so you can hook or unhook. then flip the switch and suspension rises to a preset level.. Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514100 Share on other sites More sharing options...
mechohaulic Posted October 31, 2022 Share Posted October 31, 2022 since you located the leveling valve can also try disconnecting one end of the arm; usually the lower end . with ful air pressure and ALL body parts out of harms way,, just slightly move the arm up/ down. if there's air and valve is good the bags should raise/ lower. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514101 Share on other sites More sharing options...
usrjcro11 Posted October 31, 2022 Author Share Posted October 31, 2022 .how long should it take to dump air? Maybe I did not wait long enough. Should air come out of exhaust port on leveling valve? Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514103 Share on other sites More sharing options...
Joey Mack Posted October 31, 2022 Share Posted October 31, 2022 10 seconds Quote Link to comment https://www.bigmacktrucks.com/topic/70636-1994-mack-ch-trailer-coupling-and-uncoupling-not-working/#findComment-514104 Share on other sites More sharing options...
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