Technical Service Bulletins

Is Honda Flicker or Dim Normal?

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Is Honda Flicker or Dim Normal?

This bulletin applies to all Honda models except Passport when faced with flickering or dimming headlights and/or dash lights when the brakes or turn signals are used.

This flickering or dimming happens when the battery is supplying most of the current for the electrical load instead of the alternator.

Since the early 1990s, Honda vehicles have been equipped with an electrical load detector (ELD) unit in the underhood fuse/relay box. This unit allows the ECM/PCM to regulate the alternator, switching it between high and low output to provide the best combination of fuel economy and electrical system operation.

The ELD sends a signal to the ECM/PCM that’s proportional to the electrical demand. The ECM/PCM switches the alternator between high and low output depending on several factors which include electrical demand, battery charge level and the driving cycle. When the alternator is in low output, the engine load is reduced for better fuel economy.

If the customer complains about this flickering or dimming, tell them about the ELD unit and how it works. Unless the engine won’t crank or the vehicle has other symptoms of a weak battery, chances are the flickering or dimming isn’t an electrical problem.

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