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I have a 2005 Accord LX 2.4L w/ 101k miles and a few weeks ago, the battery light came on. The battery was changed last year. After checking everything, I concluded that it was a bad alternator, so I ordered an OEM reman alternator and replaced it. The light went away.

During the alternator replacement, I felt that the tensioner pulley was spinning too freely and making a little noise. So, just to be on safe side, I got a new OEM pulley from Honda dealer and replaced the pulley. I put 41lbft on the M14 pulley bolt based on a YouTube video. The alternator and pulley replacement were separated by 2-3 days during which I drove for 2-3 hours.

Fast forward a week from pulley replacement, my battery light is coming on intermittently while driving, stays on for 2-3 seconds and goes off. My observation so far is it happens when I brake but not every time I brake. I did basic continuity/voltage drop checks. At idle with full load, 130mV drop between battery positive and alternator positive and 30mV between battery negative and alternator housing. The 4 pin connector on the alternator is not damaged. Voltage at battery terminals with full load at idle is 14.05V, and 14.28V without any load.

The drive belt has at least 35k miles on it but does not have any cracks. Could the belt be slipping?

  • Maybe a faulty reman alternator? – Moab Aug 8 '18 at 15:45
  • When the light comes on is battery voltage actually dropping? Check for short to ground on the lamp circuit? – Ben Aug 8 '18 at 16:28
  • @Ben I have not yet been able to reproduce this problem with car standing still, so not sure what voltage is when light comes on. Can you provide more details on how to check the lamp circuit? – tumchaaditya Aug 8 '18 at 16:30
  • Which engine do you have? I think the alternators are the same for the v6 and i4s. The wht/blu wire is part of the lamp circuit, normally this is battery voltage, engine running. The voltage regulator will ground this wire, sending a signal to the ecm. Which sends a signal over a comm line to the gauge cluster. Iirc there aren’t known problems with the harness rubbing, but it doesn’t hurt to check. You can do some wiggle testing as well just backprobe the circuit and wiggle the harness is various places. Also recheck the mounting bolts especially the one that draws in that round piece. – Ben Aug 8 '18 at 16:41
  • I have 2.4L I4. Just so I understood you correctly, I should be checking voltage between battery positive and wht/blu wire when key switch is ON but engine is not running and it should read battery voltage, right? And when the engine is running, it should read almost zero? – tumchaaditya Aug 8 '18 at 18:04

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