mcratchet1

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!!

Ok thanks for all the help!!! I'm going to check it out today

Ok so i have a 2006 mack mr688s vin# 032711 always would pop air out of purge valve every 10-15 seconds all day Air compressor went out so installed reman from mack as well as a new air dryer, governor, and new air line from compressor to dryer still popping off every 10-15 seconds could someone help a brother out on this? i have never had one do this thanks in advance!!!

ok finally was able to press pin out with a mini 2 ton bottle jack, the new pin i was able to push right in almost by hand is that normal? I put some retaining lock tite on it just was wondering? i used a mini 8oz hammer to tap it flush with engine block

Thanks for all the help ended up putting new cam and rollers in working on #6 eup tappet bore pin part# 20706385 are these just pressed in? having a hard time trying to get it to tap out, does anybody know of a certain way to remove pins? Thanks!!

i would not call myself a shade tree guy, i have done 3 inframe's on etec motors that i still own that have over 10000 hours on since they were done. I was just hoping to get a few second opinions from somebody who might work on them daily. I have tools and yes i know about the magnets like i said in previous post i have replaced a cam! The bushings do fail, i was able to get some specs on them from another mack dealer. the gear on cam can get pressed off and on thats not a problem. i was mostly wondering if any one has seen this same problem and just replace roller? The cam just has a few surface scratches, i know that will shorten the life of it. Just was wanting to see if anyone had an issue like this and will it hold up another year or so on just replacing the roller and pin! thanks for the help!!

i would not call myself a shade tree guy, i have done 3 inframe's on etec motors that i still own that have over 10000 hours on since they were done. I was just hoping to get a few second opinions from somebody who might work on them daily. I have tools and yes i know about the magnets like i said in previous post i have replaced a cam! The bushings do fail, i was able to get some specs on them from another mack dealer. the gear on cam can get pressed off and on thats not a problem. i was mostly wondering if any one has seen this same problem and just replace roller? The cam just has a few surface scratches, i know that will shorten the life of it. Just was wanting to see if anyone had an issue like this and will it hold up another year or so on just replacing the roller and pin! thanks for the help!!

also should i do bushings, rings, liners rod and main bearings? idk i dont want to go broke but i want it right. Besides a visually inspection what else should i look at or check? or use plasticgauge? also i did a cam and bushings about 10 years ago and my buddy worked at mack in the next town and he let me use there pulling tool i remember #6 being a pain. But my friends gone where can i get that tool? Any help i sure do appreciate

do i have to remove head to replace pin? i cant find any info on pins in the mack book i have

Can i replace the pin? should i turn the engine around and examine cam shaft?

no pin so im i sol whats the right way to go in this