Cummins/Onan 4.0 BF-1R/9500 — Testing Bridge Rectifier
Testing & diagnosis
For the Cummins/Onan 4.0 BF-1R/9500, from the Cummins/Onan service manual.
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Before you start
- Observe proper polarity when reinstalling; if installed wrong, generator voltage will not build up
Procedure
- Loosen No. 8-32 screw to remove bridge rectifier assembly
- Disconnect nylon connector, noting polarity marking of rectifier and connector
- Pull out from end bell and remove bridge rectifier from its case
- Use an ohmmeter set to R x 1 scale
- Place meter leads on points shown in Figure 70 and note readings (8 ohms or infinity)
- If any tests do not agree with readings, install a new bridge rectifier
Tools required
- Ohmmeter Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Resistance readings 8 ohms or infinity (+/-10% at 70 F)
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.