quantumleap Posted January 3, 2009 Share Posted January 3, 2009 hi all....yes i drive one of these trucks everyday for a job. its a twin steer bogie drive with a tag out the back. its also a tilt tray. i like this truck personally although we have had a few troubles with it.it has the EA7 engine rated to 470hp with a gen 3 18 speed auto shift 'box out the back.the biggest problem with this truck is it keeps killing the gearbox computers (4 so far). its done this from new. so.....has anyone had their fair share of dramas with these trucks...(and don't just say they are a piece of crap) feel free to share your problems and fixescheers"the hulk" Quote Link to comment Share on other sites More sharing options...
quantumleap Posted January 5, 2009 Author Share Posted January 5, 2009 update.....our quantum has now killed gearbox computer number 5....it lasted 2 weeks. seems this computer has internally shorted itself to ground. the tech found it after it blew several 30amp fuses....thank god for high capacity big grunt 24volt to 12volt reducers.the main power for this gearbox computer comes from 1 of the 2 main voltage reducers fitted to this truck. i still don't understand why these computers keep failing. you would think that after the first 2 that eaton would be asking what the hell is going on.cheersthe hulk Quote Link to comment Share on other sites More sharing options...
ThaddeusW Posted January 6, 2009 Share Posted January 6, 2009 I read through the Gen 3 Autoshift installation guide and it appears that the Transmission ECU can use either 12 or 24 volts (max of 36 volts). It should not have to be connected to any voltage regulator as all wiring diagrams show the transmission ECU wired directly to the batteries or electrical distribution box. This is so the power to the ECU is not interrupted during starting. I see no reason for it to be wired to a voltage regulator. Have the tech look into this and have a look at the official Eaton install guide which is filled with tons of wiring diagrams. Here is the link the the Autoshift page and the install guide in on the lower right of the page. Now I realize you might not have a generation 3 Autoshift and I reccomend talking to Eaton and find out exactly what voltage your ECU needs (I would bet Mack used the DC-DC inverter because it might be a 12V only ECU). If the older ECU's only operated on 12 volts I would start looking at the 24V to 12V DC-DC inverter as this might be the source of the problem. The voltage regulator might be malfunctioning and sending as much as 28 volts to the ECU blowing it out. Have the tech check the output voltage of the inverter, it should be 12-14 volts. It might be an intermittent problem and the only way to be sure would be to replace the DC-DC inverter with a new one. Call Eaton and ask if there is an updated 24 volt ECU for your gearbox and confirn that your current ECU model is 12V only. A Hybrid 12/24 volt system gets real hairy when electronics are involved. You have the European cab electronics/lighting that use a 24V battery bank and alternator and American systems that use 12V (ECU's and trailer lighting). If something goes wrong you might be getting 24-28 volts on a wire that can have a max of 12-14 on it and *POOf* theres goes the ECU. Get wiring diagrams for your gearbox and see if there are any relays or switches that are in the vacinity of 24 volt systems. A wire might get crossed somewhere else and sending 24V back to the ECU. If this keeps up I would look to upgrading to a Gen 3 Autoshift and wire the thing for 24V and Sell the old gearbox. I would like to see the solution to this problem. Quote -Thad What America needs is less bull and more Bulldog! Link to comment Share on other sites More sharing options...
quantumleap Posted January 6, 2009 Author Share Posted January 6, 2009 hi there ThaddeusW...thanks for the link to the wiring diagrams....this is something i have been chasing to see where everything runs and where to look for possible problems.just to confirm with you that yes it is a gen 3 18 speed autoshift with the t-bar type shifter.....the tech told me today when they installed tranny ECU number 6!!!!i have had a quick look at the link you gave me and yes it does show the main power is direct to the battery via a suitable fuse.(30amp)cheersthe hulk Quote Link to comment Share on other sites More sharing options...
quantumleap Posted January 6, 2009 Author Share Posted January 6, 2009 just been looking at the wiring diagrams from the eaton website.what a fantastic source of information!!!!!!!pity mack trucks aren't as forthcoming for the quantums!!!!!the gen 3 autoshift appears to be both 12v and 24v compatable.this leads me to believe that the voltage reducer currently used on my truck is not needed whatsoever.it could possibly be the reason behind all these failures. time and further investigation will telli will let you know more as it comes to hand.............cheersthe hulk Quote Link to comment Share on other sites More sharing options...
ThaddeusW Posted January 6, 2009 Share Posted January 6, 2009 Wire that puppy right to the batteries as Eaton instructs you to. That indeed could be the problem. Quote -Thad What America needs is less bull and more Bulldog! Link to comment Share on other sites More sharing options...
quantumleap Posted January 7, 2009 Author Share Posted January 7, 2009 yeah i agree....but as this autoshift was a factory fit rearranging the wiring harness will require a little thought. also this trucks 4 batteries went flat overnight. went to start it this morning and nothing....dead flat!!!...i suspect that since the tranny ECU was dead shorted through the reducer it was pulling power from the batteries.....but the isolation switch was off....dunno whats goin on there.cheersthe hulk Quote Link to comment Share on other sites More sharing options...
quantumleap Posted January 8, 2009 Author Share Posted January 8, 2009 update......it seems the battery problem has cured itself. after a long drive yesterday i was not really keen to shut the engine down in case i couldnt start it again.....but i did and to my surprise it fired up without a problem. our local mack truck dealer here is in talks with eaton so i have been told. seems many questions are being asked and so many answers SHOULD be forthcoming soon.i am now of the belief that yes the autoshift SHOULD be wired direct to the battery....but why it isn't still remains a mystery.will keep you up to date as i find out....cheersthe hulk Quote Link to comment Share on other sites More sharing options...
quantumleap Posted January 15, 2009 Author Share Posted January 15, 2009 update......well....gearbox ECU number 7 is now in the truck!!!apparently both mack trucks AND eaton know there is a problem with interfacing the Eaton autoshift to the mack E7 engines as fitted to the quantums!!!i took the truck over to our local dealer this morning as requested by the boss. had the truck back by mid afternoon.it seems eaton know about the unique problems with these trucks and so have produced a gearbox ECU that deals with it.....what that is exactly i don't know.by the way.....number 6 didn't fail....they just replaced it with a "new and improved" ECU.just yesterday the yellow engine warning light came on as i'm running down the highway. i tried to retrieve the blink code to see what was wrong....and no code came up...nothing at all.....it did this twice in the space of about 3 hours.i have in the past had a recuring fault code that says the J1939 link had a problem....but it doesn't stop the truck.this new (number 7) ECU seems to shift the box about 1000rpm lower that ALL previous ECU'sit also "jumps" gears when unloaded...as it should...but much better than all previous ECU'sthese ECU's also have (in the past) had a problem with moisture (water) ingression.....even though they are a factory sealed unit.....no one seems to know why or give an explaination as to why water gets inside. and no i don't blast the ECU with water when i wash the truck....in fact i'm very aware of where it is and steer well away from it when washing the cab.we will see how THIS tranny ECU goes....time will tell as to IF they have got it right THIS timecheersthe hulk Quote Link to comment Share on other sites More sharing options...
quantumleap Posted January 16, 2009 Author Share Posted January 16, 2009 i had a closer look at this new ECU today.the cover that is screwed down seems to be thicker and smooth. not like any of the other covers that appeared to be very thin with a pressed ridge around the outside edge that held the seal down.also there is what appears to be a small black rubber bung in the back. i don't know what this is for. i could only surmise that its for moisture to get out if it finds its way inside the boxcheersthe hulk Quote Link to comment Share on other sites More sharing options...
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