slingblade

alot of variables figure in such as temp,humidity,altitude etc,etc,what i always do is watch the guages,,35 on the low side,not over 175/180 on the high side

one of the RDs where i work had a bad vibration,kept telling the owner about it,nothing got done till the rear yoke on the trans finally wiped the speed sensor out

thats when they found the nut holding it loose,tighted it up and the vibration under load and at speed went away,another older RD had a very bad vibration that we couldnt find till it finally broke the rear drive shaft universal between the diffs,replaced the yoke on rear diff and the joints and 98% of the vibration went away,mack should be ashamed of themselves turning out new trucks with the issues you talk about on here and no one knows what the problem is

wow,

found a helpful PDF at jacobsviehiclesystems.com with tech info and diagnostics

thanks guys,found the relay searching out why the brake lights stayed on all the time,the jake relay was plugged in where the brake realy goes,,im going to go back through the wires and label them for their color and also re do the wiring on the motor to correct it,,

i bought this superliner and love it and have fixed most of the electrical issues with it except for the jake switches,apparently when the assessory relay went bad the previous owner re wired alot of stuff to get things working again,the jake was wired directly from the hot on top of the strip on the drivers side fire wall through the throttle switch,then to the solenoids,it was also wired into the toggle switch for on/off and the existing wiring is still there behind the panel and the diagram for the RD on here is close but only shows hi/low and the colors are different,,if someone has it or knows the link where i can pull it off the net id appreciate it,,

could be belts,my RD was doing the same thing

bigger motor?thats not a bad thing

yup,the ford relay lasted a day,49 bucks at the mack dealer and i got the correct one,now to undo all the wiring work arounds the last owner did to it,got most of it back to original except for the 3 stage jake brake wiring,this should be a challenge,,

found the problem,assesory relay under the dash section where you normally mount cb radio theres a heavy duty relay that looks like the old ford start relay,it powers up the upper buss that supplies power to the guages,lights and buzzers,going to replace it with a new ford starter relay

sad,these were tuff as nails,couldnt break them,always cranked up and any idiot could drive them,wished mack still made them this good

on my 85 superliner the guages didnt work and i traced the problem back to the circuit breaker panel using the RD wiring diagram,specificly the power busses behind the panel that supply power to the different circuits,one of them is dead,the wiring diagram doesnt show where they get power from,does anyone know?i could run a patch from the good buss to power up the dead one but id rather find the problem and fix it there,,any help would greatly be appreciated

great advice youall,,spent all day fixing lights and undoing butcher type work under the dash by mechanics too lazy to find the problem,just run a bypass circuit to get it back up,,its a nice truck with individual differential guages,trans temp,motor etc,another thing ive found is the reverse lights dont work,someone put a toggle switch on the dash to operate,,isnt it just a switch on the top of the trans?i found it but nothing when i applied power to it to see if the reverse alarm worked,this may take a few days to unscrew,,thanks for all the great tips

hi fellow truckers,bought this superliner in sedrowooly washington last week and me and a friend drove it all the way back to georgia without any problems except for the fuel sender/guage wasnt working so i had to check the level in the tank from time to time,,ive been repairing the wiring for the lights and want to fix the guages,anyone know where the guage gets its power?i had no voltage at guage