mcratchet1

ok thanks i'll look them up

so i have a 2006 mr688s (032711) the jack operates great lifting the cab but when i want to go down it will pump up and get solid and not move. The only way to lower cab is to open the line, there's no leaks or damage visible. My question is there a relief valve inside maybe hanging up? Has anybody had this problem before? Thanks!!

is there a proper technique for setting the clutch brake

Hey guys just wondering if the newer mack mru 2015+ with t310 and t318 transmissions, if the clutch still gets adjusted the same way as the older mr688s models? By old way i mean put a wrench on clutch adjusting bolt with prybar have someone step on clutch and push in spring to turn the bolt Thanks

what do you mean by common failure? compressor hose plumbed into exhaust manifold?

yes from dash, ill take a look at check valves should i put a gauge on the wet tank itself to see if its losing air somehow? could it backfeed thru a valve?

etec e7

no it was doing it before injectors were installed oil sample says soot%0.4

so getting back to this, i have checked ever where for a leak cant find one truck holds air pressure over night also

i have a 2003 mr688s 400hp blowing black smoke in bewteen gears truck runs great no problems. New turbo and injectors beginning of this year, should i be concerned or just let her roll?

i found it a pinched key switch wire

yes already bypass it

2006 mr688s (032711) under dog box all 4 power relays buzzing when i try to start all fuses good, batteries are good, just changed starter since i had one no difference i check and cleaned grounds no change even new key switch any help would be great thanks!

on all 4 power rely's #30 has power and #87 is ground

whats a typical cause ? rubbed wire?

ok ill check there 70 amp relays

ok found high/low beam relay bad changed been running with no problems for a month now did same thing 2x today also this morning truck would not start. When i turned key only heard buzzing coming from these 4 relays. Does anybody know what these control? im guessing one has to be starter i cycle the key a few times then it cranks i checked to the wire had 11.50 but when i turned key switch dropped to 5.5 volts now truck will not start going to just start tracing wires unless someone could help a brother out Thanks!!!

thats a good idea but they dont work nights here

tell me which ones to take off and i would gladly do so to test it out

yes, the only thing i do not have a pin tester to check relays, but the did have good scratches and fit tight we are a small private pump company we have 7 mack trucks I called mack for a diagram of the fuse and relay layout in the dog box but they said they cannot give me that info they are never helpful 032711 is the last 6 of vin do you have access to fuse and relay location? Thanks

actually i just replaced the key switch monday, problem seemed to go away until yesterday it dropped out while he was pumping

ok no luck on bypass same problem

u talking about battery disconnect switch?

ok i have a 2006 mack mr688s (032711) with a concrete boom sitting on it. The truck would act like it was shut off but never cut out, the code is coming from vecu. It was happening once a month then once a week now 2X daily i checked from the batteries to power relays and everything in between and cannot find anything, the starter, alternator, engine grounds, frame grounds, the ground relay on drivers side by air filter behind little black cover its very annoying especially while pumping concrete any other trouble shooting advice would me great thanks!!!

i am having same problem with my 2006 mr688s (032711) i followed all the steps above and had no luck it was doing it once a month then once a week now 1 or 2 times a day its loses power like it was turned off but the truck never shuts off and the code is logging from vecu any other ideas? thanks!!