Caterpillar — Varistor - Test

Testing & diagnosis · Varistor (CR7)

From a Caterpillar owner's manual covering: 3306B, 3406, 3406E, 3412C, SR4B. Check it applies to your exact model before use.

Applies to: Caterpillar 3306B, Caterpillar 3406, Caterpillar 3406E, Caterpillar 3412C, Caterpillar SR4B

Procedure

1. Using an ohmmeter, place the ohmmeter across the varistor. The resistance should be a minimum of 15000 ohms.
2. Disconnect either lead of the varistor (CR7).
3. Place the test light across the varistor.
4. Observe the results. The lamp should not light.
5. Reverse the test light.
6. Observe the results. The lamp should not light.
7. If the test light illuminates in either direction, there is a short in the varistor. Replace any faulty varistors with comparable operating characteristics.

Full service-parts list: Caterpillar 3406 →, Caterpillar 3406E →, Caterpillar 3412C →, Caterpillar SR4B →

Source: Caterpillar owner's 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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