Cummins/Onan — Magnetic Speed Pickup Unit Adjustment
Adjustments · Magnetic speed pickup unit (MPU)
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Procedure
- Measure MPU resistance; replace if not between 1,000 and 1,050 ohms.
- With the MPU removed, rotate the ring gear until a tooth lines up in the center of the mounting hole.
- Thread the pickup in gently by hand until it just touches the ring gear tooth.
- Back it out 1/4 turn and set the locknut.
- Check output voltage; replace the MPU if output voltage at cranking speed is less than 1.5 VAC.
Tools required
- Ohmmeter Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 1,000 to 1,050 ohms
- Back out 1/4 turn
- Output at cranking speed at least 1.5 VAC
Source: Cummins/Onan 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.