Caterpillar — Fault Identification for Earlier Digital Voltage Regulators

Testing & diagnosis

From a Caterpillar service manual — check it applies to your exact model before use.

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Procedure

1. Check excitation: use a multimeter across F1 and F2 set for VDC, or view parameter :55. If OK go to step 2; if not, go to step 4.
2. Check alarm status: display flashing or alarm output off (open circuit) means an alarm is active. Go to Alarm Clearing.
3. Check alarm fault log parameter :95. If it shows 0000 no new alarm has occurred; otherwise go to Alarm Clearing.
4. Check fault status: display flashing or fault output off means a shutdown fault is active. Go to step 5.
5. Check shutdown fault log parameter :92. A 7xx number is a resettable fault; a 8xx is non-resettable; a 9xx is a severe fault and the unit must be replaced.
6. Reset a 7xx fault by selecting parameter :96 and pressing the function key; reset an 8xx fault by removing all power, correcting the problem, and reapplying power.

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.

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