I have a 307C where the temp gauge isn't working. When ignition is turned on it will go up to max and down again (like the other ones) - but it doesn't seem to rise when temp going up (I'v noticed a couple of times that it will actually show temp, but after a while it will drop back down to min). So far I'v measured the temp sender - measuring about 13Kohm when cold, and it will go down to about 3Kohm when heating up (most likely not fully warm when I tested it). I'm not sure what values would be expected on these senders, but I recon this can be correct. Any tips on what else might cause this, and what to troubleshoot ?. thnx
Check Gauge & wiring by removing wire at temp sender and ground it (earth) , gauge should go max hot temp reading. It would be best to do this when you know that you are getting incorrect reading in cab. If gauge in cab responds correctly you have just checked out the wiring and gauge. IF gauge does not respond disconnect wire coming from sending unit at gauge, use jumper from ground to where you removed wire from gauge again it should read max hot. that checked out the wire coming from sending unit to gauge. Look at it as battery coming into gauge when you turn on power going thru gauge/wire/sending unit to ground, with the sending unit being the control depending on heat.
you follow this chart good luck rankothge
Do you have a better resolution image of this ? (a bit hard to read). thnx for the replies
yes sure, you may save it and open and zoom it
I think I have narrowed it down to be a monitor problem - any one ever opened these things up ?. Or know anywhere one could buy them used - seem to be costing a sh*** load of money for something this "simple" Bet it's a bad solder or something, as it sometimes seem to be working for a little while....
The monitor is not designed to be opened up and allegedly nothing in it is serviceable, but that doesn't mean to say you can't do it. I've seen loads of problems on circuit boards that were nothing more than "dry" soldered joints. Re-melting the solder on the affected joint and allowing it to cool again was all that was required to fix the problem. If you want an electrical schematic them PM me with your e-mail address and the full machine Serial Number. Please don't post them here.
Ok, I'l pm you - might be a few days though as I'm not at the place where the machine is at the moment, but will be back there sanday/monday. Meanwhile any tips on how to "open" the monitor ? (seem to be some kinda of plastic pin that have it "locked" in place - but might be mistaken thnx again, I'l get back to you
No tips from my end. I've never opened one on a machine that small. Maybe someone else can offer suggestions. I think if I were you I'd get the electrical schematic and troubleshoot it again before starting to dig into the monitor.
yea, doing the monitor is the last resort (it's roughly £2500 over here), I'l get back to you in pm when I got the serial etc
When working on that printed circuit card/board wear magifcation glasses and look for possible cracks on board due to vibration . Cracks can happen near connectors and larger components.
Flash of inspiration time ................. I DON'T think it's the monitor. Why..? Because in the OP he says "When ignition is turned on it will go up to max and down again (like the other ones)". This is the "power-on self test", effectively the monitor panel testing itself that all the different indicators within it are functioning, just like the dahsboard on your car/pickup when you turn the key on. If the coolant temp gauge on the monitor goes full scale (low to high and back again) when you first turn the key on the problem is in the signal coming from the temp sender to the monitor, not in the monitor itself - IMHO. I would be looking at and cleaning with aerosol contact cleaner every major harness connector betwen the temp sender and the monitor panel. There may well be 4 or 5 of them.
I tried accessing this chart through SIS and Cat has a poor scan of this chart. Not sure how good a dealer you have there but the chart is in media # RENR4043.00 Maybe dealer has an original paper copy you could make a copy of for checking this problem.
Does this work any better ...?
Not one of Cats better scans is it? Hopefully mawrick can make it out enough to do his tests.
Well I sent him the electrical schematic as well. Hopefully he can sort it. I'm sure he'll be back here for help if he gets stuck.
Hey Nige! Even a blind hog finds an acorn every once in a while...... Seriously, I'd bet you're right. Mitch
That last print was better yea I'l post back once I'v had time to check these things (will be a little while though), thanks again for the help!
If you ground the pin for coolant temp at the monitor connector and the gauge doesn't max out your problem is in the monitor, perhaps a bad solder joint at the connector to the board.
Hi I know this is an old thread but I’m having the same issue on a 311C and was wondering if you found a solution?
The OP has not been back since Oct 2013 so I doubt you'll get any response from him. Only thing I can suggest is to follow the procedure in the troubleshooting flow chart in post #14 above ......
Ok thanks, I’ve ordered a couple of new temp sensors I’ll start with that.
Did you the procedure indicate that the sensor was the problem.? If not you could have nothing more than a broken wire somewhere and be still in the same position after wasting your money on a new sensor.
It’s a strange one when you wiggle the sensor it seems to come back online and then throughout the day it will randomly return to working sometimes hours at a time.