Hello all, This is an amazing forum and I thank all of you for the contributions. I have searched and not been able to find a solution. The most likely similar scenarios are posted: HeavyEquipmentForums HeavyEquipmentForums I was using the 279C2, parked and then the next day couldn't get it to turnover. All power, lights, fuel pump all come on but when you turn the key, nothing. After flipping the cab up and down a few times, checking all fuses I got it to start ran for about 30 mins, parked and now won't start again. I flipped the cab, checked fuses in the back and behind the seat and was considering by-passing the seat switch but am unsure exactly where it is. The wiring schematic shows 4 wires: 180-CH28 (GN-14) 200-CH29 (BK-14) G983-CH31 (GN-18) G985-CH35 (PU-18) I believe these are directly behind the seat going into a connector with a pair of red/black wires. How is one to jumper this seat switch (if this is indeed it)? Any other potential troubleshooting steps? Thanks!
Hi I would start by doing some basic checks first check fuses (with multimeter or led test light) check wiring visually check starter motor,battery and neutral start relay for loose connections (the relay is behind the starter for early model) especially earths. once these checks are done I would then check the armrest switch and the seat switch if that does not isolate the fault you will need to check that the starter motor solenoid is receiving power and work your way back from there do you have an electrical schematic there have been a few posted on here over the years? if not let us know
Thanks Mark, I have tested all fuses and wiring. When you say early models, is 2012 considered early? I haven't made my way back to the starter, appears to be buried back there haven't figured out the best way to access it yet. I do have a schematic named "CAT_279+schematic.pdf " It is interactive and will display the machine location and schematic location. I'll let you know what I find out on the starter. Thanks!
Update- this is resolved. It was the starter relay. After spending many weekends looking through the schematic and a few trips down to the CAT dealership (who was willing to give me some free advise), I was able to determine that the plug going into the relay had switched 12v power on pin 86. and I was able to get the starter to turn by supplying power to pin 87 (304 - E49 - WH 12) which then only left the relay as a potential culprit. Part #115-1615 for about $30 got his bad boy running. If anyone runs into this issue, save yourself some time and just pull the alternator out of the way. The starter relay will be on the left hand side about 12 inches away from the starter and below the muffler. CAT mentioned many of the new D series can have a similar issue due to a bad cab ground (I replaced this too, mine was getting caught but not terrible).
Glad you got this resolved. You mention that you have a pdf interactive schematic. To check if it's the correct one for your particular machine take a look at the "Cover Page" (see below). In the pdf it will probably be on Page 2. Is your machine Serial Number shown in the list of applicable machines right underneath the illustration below.? If not, post or PM me the Serial Number and I'll send you a schematic suitable for your machine. you never know, it may come in handy in the future.
I realize this is an old post but I had the exact same issue on the same machine today. Starter relay went bad and this post saved a ton of time. Thanks!