A couple months ago I bought a non working Case 90XT. I have since got it working again with the exception of the interlock system. I’m able to drive it and got the loader working but only temporarily because I jumped the solenoids. The wire coming out from under the seat is not plugged into anything and doesn’t look like it’s been plugged into anything for a long time. I cannot find where it is suppose to be plugged into so I can see if maybe the jumper the previous owner put in is still there. I’m finding that every single problem with this machine was 100% caused by the previous mechanic. Their fixes for everything were only temporary because everything they did they did with shortcuts. So I assume it’s the same with the seat safety switch bypass. So my question is, where does the seat switch plug into?
Do you have access to drawings and diagrams for this machine? While my machine is a CAT, those drawings and diagrams were/are priceless. A number of VERY knowledgeable members jumped in to help me. Even with drawings etc. But it took time for me to study the drawings and nomenclature before it made sense. Interlock is the absolute KING PIN safety device on these machines. It controls virtually everything on my machine. The upside is, on my machine- once i understood what components are integrated with the interlock circuits; the problem was much easier resolved. Mine turned out to be severly corroded chassis, frame and cab grounds. Even a significant ground strap had essentially disintegrated. And it was doing STRANGE intermittent things… It would start and run sometime. It would move sometimes… The latest was the lights had to be on for it to start. But in summary, the Interlock would not allow the brake switch to turn off the park brake… While we tend to be cautious (and we should be) of online document services, i found that going to CAT’s document service was more reliable and very inexpensive actually. And it was based upon serial number specific documentation. Of course site members also have access to reliable docs as well. And im very grateful to them for helping me. I had been fight my issues for more than 3 months…and they pointed me to the solution within minutes. Good folks here!!! Remember, Interlock prevents fatality accidents on these machines. Good luck!
I have all the manuals to the machine but the manuals don’t take into account previous owners monkeying with the machine modifying things. So although the wiring diagrams show all the circuits they don’t tell me exactly where the seat switch plugs in. There are no wires long enough laying in the machine that would reach the seat switch
They probably removed the wire/connector as you have commented. Can you tell in the diagrams what color (in CAT’s case the number) wires that connect the seat switch to Interlock harness? Connector locations can be mind boggling as well. In my case, I had to raise the cab to gain access to the seat switch, its pigtail, primary interlock ecm module, armrest switch, and the wire/connectors. Including one at the switch pigtail end and the other at wire harness junction. Then had to find the wire and the pin# on the interlock ecm connector to test the circuit continuity… According to the diagrams; are your armrest switch and seat switch in series? Mine also has (of all things…) the fuel gauge in series with them… I know you are pulling out your hair. So I’m throwing out some lessons learned in my trouble shooting. Do you have a code reader? I bought a CanDo that could read codes on my machine. Not the history but only the current codes that the interlock ecm is throwing. Mine was throwing a code like ‘low voltage park brake circuit.’ That was my first clue as to the interlock ecm ‘listen circuit’ having more than one device in series with it. The rest is head scratching, looking, graveling and thinking. On the CAT, the armrest and park brake switches are also resistance based devices. While they are normally open or normally closed, the interlock has to see a certain voltage based on a resistance voltage drop in each of these switches/devices…. E.g. 4.6v vice 12v or zero volts etc. I actually found that little gem of a detail while watching a youtube video… Bypassing these switches are not an option on my machine. Unless of course you place a resistor across the circuit. The people who hacked my machine- were certainly not resistor level people.
Check the lap bar switch harness for any wires that have been cut off. Looks like that harness is where the seat switch connects with.