Electrical problems can be one of the most tedious things to repair on nearly everything. I decided to post this, not to offer specific info, but to show an example of some of the methods one must employ to troubleshoot electrical failures. Just some of the crap mechanics have to go through blindly, feeling your way as you go. Bah ha haha Saturday, yep, at work. Boss stopped in, told him (jokingly) "One of these days...I'm gonna hang you and that rental sales guy from the shop overhead crane! You guys are driving me crazy!" Three times in the last two weeks, we've had a crawler dumper that boss had purchased come in and I find out we were waiting on it to be delivered to a rental job. What? A used machine you purchased, no nothing about, and got a rental job waiting on it! :Banghead Well this is the latest one. Komatsu CD110R-1. Unloaded off truck late on Friday, rental customer is coming to get it on Monday morning. I give the machine a quick check, seems to be a sound machine. No leaks, runs and operates good. Engine oil is clean, antifreeze good. Has a few minor things to do, nothing that would hinder rental. But one problem, cab heater not working. I told boss, air conditioning is more about operator comfort. But heat, involves operator comfort, but it's been below freezing here the last few nights, winter is coming, you can't defrost the ice/frost from the windows without heat, kinda necessary, and for certain something a rental customer will complain about. So, it's Saturday, and I'm in here trying to figure this thing out. Well, rip the cab apart, pull the seat, and tear into the heater box. Yep, this is my tight working space for the day. Dang, my knees sure feel it. Checked the harness connector where wiring goes into heater box, had power and ground. Pulled the control panel, no power on any of the switches. So, tear into the heater box. Seems pretty simple in there, nothing electronic, mostly old school controls. Problem is, no wiring schematic, have no idea which wire goes where. And Komatsu color coding of wires is no help. Red wire with black dots, yeah, right, seems like there's red wires with black dots going everywhere. LoL. Only one thing I can do, rip the heater/AC control harness out of it and do surgery, slice it open, so I can tell how power supply is working. Even then, it's a time consuming process, and things are still not all that obvious. But tracing down power supply paths, it appeared that power supply first went to the fan speed resistor panel. Typical speed resistor panel, one low resistance wire coil for mid fan speed, and one high resistance wire coil for low fan speed. But the power input to heater box went to a ceramic resistor in between the two speed coils. Hmm, haven't seen that before. Don't really know why they are using the resistor, but it had power coming in on one side, but nothing coming out the other side. Well, it's worth a shot, put a jumper lead across the posts.
Connected butchered up harness to the various connectors, and voilà, everything works. Sweet! Decided to cut the two wires that feed the resistor and join them with a butt connector until I can order a new resistor panel. Pulled the harness back out, got it all wrapped up like it was before I got holt of it. Got harness routed back through all its bends and tucked behind various components, bit of a pain, But got it all sorted out and put heater box back togehter. Still puzzled why Komatsu routed power input through a resistor. There's no electronic stuff in here, mostly old school stuff and a few servo motors to operate air duct flaps. Best guess I could come up with is the resistor would maintain a constant fan speed regardless of voltage changes from alternator output. Oh well, 5:00, time to go home for some bit of weekend, and wait for the next emergency from those two jack legs. :tong
Atco, Are you sure it's a resistor and not a fusible link? They are used more to protect wiring from a heavy draw that could melt the wiring before the breaker opens. Just a thought.
Well, I don't know BillG, haven't seen this before. I'm thinking it is a resistor because they located it on the speed resistor panel which is always in the air flow duct of fan to keep resistors from burning up from resistance heat by cooling them with air flow. I checked the circuit with the fan on full speed and it was pulling less than 10 amps. I just keeping my fingers crossed that this temporary repair will work until I can order a replacement resistor panel on Monday.
Atco, Is that a 12 or 24 volt system in that dump?
It's all 24V BillG, including the fan motor, relays, and duct flap servo motors.
I haven't been able to get into one of those but the old Komatsu excavators used a resister to set different fan speeds. Nice job on the harness and repair work.
LoL, well, being of small frame, sort of a good and bad trade off for me John C. Yes, it allows me to get in tight spaces, but...sure as hell uncomfortable on my old bones being wadded up for couple of hours.
After reading "electrical problems" and the rest of the story, I was relieved to hear it still worked after you got it all buttoned up. :usa
LoL, I was a man on a mission RobVG. I was determined to get it working if I had to mount a weed eater motor in there to drive the fan.
dear sir. trully... i really love and enjoying electrical problem hahahahaha sorry for english :Banghead if i can write in english good, maybe i write here more and more and ask a lot off question.. good work sir. in a small cabin with big body its very hot didnt sir? but with my small body , it doest really hot hahahaha ointhead good work all good job hope you all in very good condition...
Have you taken a peek at the harness mounted to the new PACCAR engine? It's all but impenetrable, for repairs, but I'm sure it will rub through or otherwise get damaged. It has sort of a hard foam coating, and I'm sure their goal is to eliminate the practice of repairing harness's and force replacement.
Atco, that device looks to be a large thermal fuse (for current carrying capacity). If any printing is still visible on the body it will indicate the temperature it is rated for, possibly even current capacity on a unit that size. If the resistor elements checked within specs it was likely no more than a nuisance failure. The resistor on the right side of the image though looks to be cracked, if it is, it may have been leaning towards that fuse hastening its demise. An electrical supply or electronics (parts) shop should be able to come up with something if you have temperature and current requirments. Seems most of the available units from the typical suppliers (newark etc) max out at 15amp. Thermodisc (one manufacturer of thermal fuses); http://www.tod.com/searchProducts.asp?PageID=10&TechnologyID=2 Alex.
This maybe a little off topic ....When fixing a wiring harness one day I got frustaded with the size of a roll of tape , i think y'all know what i'm talkin about ...So i'm thinkin why not make a small roll of tape ?? So i took a small roll pin and wound the tape around the pin making a small roll of tape ...When in tight areas it works like a charm ....I've spent sometime and money trying to patent this idea but it seems all the lawyers want is money ....Just a poor country boy here ...
I thought of that also but I just laid the roll down flat and cut it in half. Now the tape will only go half way around a wire loom Merry Christmas!
Try this one more time (short version), That device looks like a thermal fuse. If you are lucky you may be able to see the temperature rating printed on it. It may have been a nuisance failure, but the resistor on the right in your photo seems to be cracked, if it is, you'll want to replace it as it'll eventually vibrate enough to spit entirely. It may also be the cause of the thermal fuse failure if it is indeed loose and leaning towards that fuse. Alex.
That a good one koldsteele i must remember that!