rahpwr Posted March 16, 2006 Share Posted March 16, 2006 Hey All,First time visitor and I hope thisis the appropriate place to inquire about this. If not please let me know where I might need to be....We recently acquired a 1982 Mack tanker from the Minnesota DNR. This truck started it's life as a 5000 gallon jet fueler from the USAF. The DNR offers these used trucks free to fire departments "as is". We had the chassis chopped down and we've spent the last months wiring it up as needed.Well, it's nearly complete except for one critical problem. Not only does it not have a back up alarm, it has no reverse lights whatsoever. I pulled the cover off the gear selector and saw there's a switch in place for the Neutral position (which I assume is a safety switch) and noticed what looked like a spot to mount the same switch type for the reverse position.I know what you're all thinking, but I can't seem to get in there to get the other switch out. Nor can I risk disabling the second out fire truck for any amount of time. I have some pics of the example I will add when I get in to work tomorrow. Anyone know what part I'm after? Part #? Where I can get it? I talked to Napa and they had something in the ballpark (part # NS6581) but nothing that appeared to mount from the side (or lacking an L shape to mount it vertically)The info I do have off the truck, for what it's worth:1982 Mack VIN# 1M2B112C3CA001981TRANS: 11KBAH185RP4CHASSIS: BR549Any info is much appreciated! Thanks!!! Quote Link to comment https://www.bigmacktrucks.com/topic/946-backup-switch-for-gear-selector-automatic/ Share on other sites More sharing options...
Barry Posted March 16, 2006 Share Posted March 16, 2006 Looks like you have a model: DM492S there! It should have an Allison MT643 Tranny...I can't look up parts for the Allisons, but you should be able to call any Allison dealer for the back up switch. Quote Barry - Watt's Truck Center Parts Manager and BMT Webmaster...1-888-304-MACK Link to comment https://www.bigmacktrucks.com/topic/946-backup-switch-for-gear-selector-automatic/#findComment-4854 Share on other sites More sharing options...
rahpwr Posted March 16, 2006 Author Share Posted March 16, 2006 Thanks for the info! For what it's worth, here's the truck and the gear selector with the cover off. Not much room to work with! Quote Link to comment https://www.bigmacktrucks.com/topic/946-backup-switch-for-gear-selector-automatic/#findComment-4858 Share on other sites More sharing options...
AutomaticMack Posted March 17, 2006 Share Posted March 17, 2006 Howdy! The back up switch on that trans should be located on the passenger side. Forward and up a few inches of the dip stick tube. If I had to guess it has screw in plug and just needs to be unsrewed and screw the new switch in. It uses a hydralic pressure switch kinda like a brake light switch on the old ford cars and trucks. In a pinch I have used a pressure switch from a CAT front end loader. I would say contact United Transmission Exchange out there in Calf. and they will set ya up with the right switch for around 20 bucks or so +/- They are a wealth of info and parts. Oh I almost fergot, If there is fluid in the trans. dont remove the plug while the engine is off or all the fluid will pour out, Maybe if yer quick enuf with the installation you wont loose all your fluid. I usually leave the truck running shifter in "N" brakes set with chocks parked over the pit in the barn, and swap the switch out. With the truck at idle in "N" there will be no hyd. pressure applied the Reverse circuit in the trans. therefore no oil to come out. UTXchange.comPhone 1-800-527-1637Fax 909-384-8145 Quote Link to comment https://www.bigmacktrucks.com/topic/946-backup-switch-for-gear-selector-automatic/#findComment-4869 Share on other sites More sharing options...
rahpwr Posted March 17, 2006 Author Share Posted March 17, 2006 Thanks for the info!I assume this is where you're tellin me to go? http://www.utxchange.com/Allison%20Transmi....%20Switch.html So the switch is down in the transmission itself? I guess I just assumed that the box in the cab would contain that. Anyone know if I'm wrong on that switch I took the picture of then? \I'll have to call these guys and see if they can hook me up next. Quote Link to comment https://www.bigmacktrucks.com/topic/946-backup-switch-for-gear-selector-automatic/#findComment-4883 Share on other sites More sharing options...
rahpwr Posted March 17, 2006 Author Share Posted March 17, 2006 Thanks for the info!I assume this is where you're tellin me to go? http://www.utxchange.com/Allison%20Transmi....%20Switch.html So the switch is down in the transmission itself? I guess I just assumed that the box in the cab would contain that. Anyone know if I'm wrong on that switch I took the picture of then? \I'll have to call these guys and see if they can hook me up next. Quote Link to comment https://www.bigmacktrucks.com/topic/946-backup-switch-for-gear-selector-automatic/#findComment-4884 Share on other sites More sharing options...
rahpwr Posted March 17, 2006 Author Share Posted March 17, 2006 Sorry for the double post earlier.I called them up and ordered the universal Allison transmission back up switch for the side of the housing. AutomaticMack I'm going to be going off of your info, if there's anything more info I can get, let me know!!Thanks Again!! Quote Link to comment https://www.bigmacktrucks.com/topic/946-backup-switch-for-gear-selector-automatic/#findComment-4890 Share on other sites More sharing options...
AutomaticMack Posted March 18, 2006 Share Posted March 18, 2006 I do have a copy of the Allison Owners Manual for the 600 and 700 series trans. I copied from the Allison Corp. website a few years ago. It is in Adobe Acrobat format and zipped for quick email. Send me your email address and I send you a copy. Very good to have! Quote Link to comment https://www.bigmacktrucks.com/topic/946-backup-switch-for-gear-selector-automatic/#findComment-4899 Share on other sites More sharing options...
AutomaticMack Posted March 18, 2006 Share Posted March 18, 2006 Heres the Allison manual Quote Link to comment https://www.bigmacktrucks.com/topic/946-backup-switch-for-gear-selector-automatic/#findComment-4909 Share on other sites More sharing options...
rahpwr Posted March 22, 2006 Author Share Posted March 22, 2006 Just an update:I went under the truck and looked for the spot and found it right where you said it'd be....and there was already a switch there. I have no idea what it could be going to. I tried to trace the wires back but it wasn't that easy. I tested the voltage with the truck running in and out of Reverse and found it was working so I will probably just splice what I need onto the wires that are there.Thanks! Quote Link to comment https://www.bigmacktrucks.com/topic/946-backup-switch-for-gear-selector-automatic/#findComment-4975 Share on other sites More sharing options...
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