My Bobcat 553 interlock just started acting up a couple of days ago. I noticed that it would only "lock up" when it wasn't at idle. Today I was watching the voltage meter on the panel and saw the voltage creeping up from ~14V to eventually maxed out ~18V. When the voltmeter creeps into the range above 16V or so the interlock lights all flash and everything locks up. I've gone through the forum threads here and removed/cleaned the seat sensor, safety bar switch, park brake switch, and even removed/cleaned the interlock solenoid. Everything seems to be functioning as it should: when you start up the lights for the various safety devices light up as they should (the seat, safety bar, parking brake..). At first everything seems fine - then, once you raise it above idle, the voltage begins to slowly creep up and it locks up. But it doesn't just "lock up" - the interlock cycles on-off-on every few seconds. Again you can watch the voltmeter and the "off" state (unlocked) corresponds with the voltage dropping down to 14-15V range. Or you could say the ON or LOCKED state corresponds with the voltage spiking to 18V. Has anyone seen this? Am I on the right track? Do I need a new alternator/voltage regulator or a new battery or both? Any help would be very much appreciated.
You will need a new alternator, or have it rebuilt with a new voltage regulator. The interlock controller self protects from high voltage. Anything over 15 volts means the voltage regulator in the alternator is not doing its job.
Thanks Ozarkag! That was extremely quick response - I sure appreciate it. I just went out and pulled the alternator/removed the regulator. I'll try to source the regulator next. So far all I'm finding are (VERY EXPENSIVE) alternators!
Found the regulator at reasonable price on ebay. about a week for shipping, so I'll let forum know if this fixes the interlock issue. Luck!