Test Alternator Diodes - AR15.40-P-9301-02MFG
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Engine 139 in model 118, 177, 247
| Risk of accident from vehicle starting off by itself when engine running. Risk of injury (bruises and burns) resulting from working on the engine while it is being started or when it is running. | Secure vehicle to prevent it from starting off by itself. Wear closed and snug-fitting work clothes. Do not touch hot or rotating parts. | AS00.00-Z-0005-01A |
- Connect engine tester with oscilloscope (030).
- Start engine.
- Switch on low beams.
It is not possible in this test to assess the exciter diodes.
- Assess diode harmonic contents at 3000 rpm (engine speed).
- Switch off engine.
An example: Harmonics, if diodes are OK (peak stresses possible but of no significance)
Example: Harmonics when a positive diode is defective (example)
Example: Harmonics when a negative diode is defective (example)