Caterpillar — High Voltage - Troubleshoot
Testing & diagnosis · Digital Voltage Regulator
From a Caterpillar service manual — check it applies to your exact model before use.
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Procedure
- Check that the regulator part number is proper for the application; if not, install the proper regulator.
- Stop the generator set and observe the display; it should contain a number.
- Check DC voltage from terminal B+ to B-; acceptable range is 18 VDC to 32 VDC.
- Verify parameters :01, :02, and :15. Check parameter :50 and compare actual frequency to verify generator type.
- Check PM inputs (26, 28, 30); expect approximately 95 VAC at 60 Hz and 79 VAC at 50 Hz.
- Check sensing inputs 20 to 22, 22 to 24, and 20 to 24; all three readings should be balanced with proper PT ratio.
- Disconnect accessory wiring from terminals 3, 5, 6, 7, 40, 41, 42, 43, 44, 45, and 50 and operate at no load to isolate a faulty accessory.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- DC voltage B+ to B-: 18 VDC to 32 VDC
- PM inputs 26/28/30: approximately 95 VAC at 60 Hz, 79 VAC at 50 Hz
Source: Caterpillar service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.