On our 318B excavator, the cat hour meter supply in the machine is experiencing low voltage @ 16v (I am assuming that is low) & when a test light is put on it, it will not light up & the Cat hour meter only records a fraction of the time actually spent when running the machine. Likely it should show 24v? When the meter is powered up on the bench with a 12v battery it counts up the hours correctly. Any idea where to look for the problem? Ser # on the machine is 3LR00468. Thanks
That sounds crazy. You're measuring 16V to the meter on a machine with a 24V system and it isn't measuring hours correctly, but you put 12V on it on the bench and it counts correctly. What's wrong with that...?
It seems to me based on the alternator problem we had on a 318 lately that the 24 Volts (nominal) system has a 220 ohm resistor that reduces this voltage to the 14 Volt range. However, I believe that the hour-meter is rated for 12 to 36 Volts. It could be a high resistance connection or a open in the conductors to the hour-meter.
I apologize for neglecting to include this; the system (24 Volts) are passed through the 220 ohm resistance thereby reducing it to 14 Volts, inorder to excite the alternator and the hour-meter is in a parallel circuit with this.
Thanks for the comments. I wonder if any one has a wiring diagram that pertains to that section that could be posted, so we could trace it back & find the problem? I think it may be bad connection somewhere along the feed.
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Turns out that we think it was a bad connection on the "R" terminal on the alternator. We pulled the alternator off & sent it out to be tested & everything tested good. Put it back on & cleaned all terminals & now it works good.