Kohler — SCR Module Test Procedure

Testing & diagnosis · Silicon Controlled Rectifier (SCR) module

From a Kohler service manual covering: 12RES, 8.5/12 RES, 8.5RES. Check it applies to your exact model before use.

Applies to: Kohler 12RES, Kohler 8.5RES, Kohler CH20 engine, Kohler CH 740 engine

Procedure

1. Set the ohmmeter to the RX1 scale.
2. Connect the ohmmeter from (+) to (--) on the SCR module; read high resistance one direction, low the other.
3. Connect the ohmmeter from AC1 to (+); read high resistance in both directions.
4. Connect the ohmmeter from AC1 to (--); read high resistance one direction, low the other.
5. Repeat steps 3 and 4 for AC2.
6. Connect the ohmmeter from G1 to (+); read low resistance in both directions.
7. Repeat step 6 for G2; read low resistance in both directions.
8. Connect the negative (--) lead from the DC power source to the positive (+) terminal on the SCR module.
9. Connect the positive (+) lead through the lamp in series to terminal AC1; the lamp should not glow.
10. Connect the jumper with resistor in series from positive lead to terminal G1; the lamp should glow.
11. Repeat steps 9 and 10 with AC2 and G2.
12. Replace the SCR module if any check indicates a bad module.

Full service-parts list: Kohler 12RES →, Kohler 8.5RES →

Source: Kohler 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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