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Just took my 01 EX to dealer for passenger airbag recall yesterday. Later in day, battery light on dash turned on right at a shift point (auto trans) when accelerating normally after pulling onto road.Checked voltage on battery with car not running- 12.5V, running-13.4. Took it to auto parts store, no codes, but checked battery, said it needed charged and alt had bad voltage reg. Nothing weird going on with car other than battery light on. Get a second opinion? Battery is less than a year old, but it has run down just leaving parking lights on under 4 hrs, but this happened a few weeks back before batt light came on, and when I took car to have checked at battery dealer, they said battery and charging looked OK. Comments welcome! Thanks.

 
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Is the alt belt tensioned properly?

 
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That's a good question...just assumed it would be..but I'll check that. Thanks!

 
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Unlike the timing belt, 7th-gen accessory belts don't have automatic tensioners, so when they age and stretch, they tend to get loose, esp when running through puddles or heavy rain that can lubricate the pulley/belt interface.

The tech that diag'd the regulator problem may've seen a problem that loose manual belts can cause -- if the alt isn't turning a consistent speed, the regulator must work harder to maintain proper charging, which heats up and stresses the part. Heat and vibration are the enemy of all electrical components, so best to swap that regulator if your budget allows it.

There's disagreement among manufacturers as to which solution is better:

Automatic pivot arm-style tensioner:

(): constant pressure on belt eliminates squeak

(): adjusts for belt stretch without need for regular service

X: constant pressure dangerous if belt neglected; can result in spectacular failure and damage to nearby engine components

X: requires all accessories be on one serp belt, to reduce cost

X: aftermarket auto tensioners can vary wildly vs. the correct OEM part as far as tension, esp on a model as old as a 7th-gen.

Toyota for example, is moving away from manual tensioners and standardizing more expensive auto tensioners... so perhaps these days they're the better solution. Not IME (had one explode and take out my timing cover and timing belt on my '99 Escort), but that's progress.

Manual tensioner:

(): doesn't require belts to be reinforced for constant pressure, so belts can be spec'd a bit lighter

(): belt will squeak or cause the dash light to come on, if there's a need to adjust.

(): No pressure on the belt except what is required by spec, no more -- belt will squeak and cause charging issues long before they fail

X: Must require regular service (though it's not THAT hard)

X: If warnings are ignored, there's a risk of glazing on pulleys and/or damage to the alt

Let us know what you find!

 
Rep Power: 519

Please don't try to imply that some unscrupulous dealer did this to your car.


Loose belt check.
Do the standard alternator tests.
Then check the alternator mounting bolts and the bolt for the bracket on the bottom. Loose bolts can cause all sorts of havoc due to the alternator losing its ground path.... Up to and including frying the PCM.


That's to be expected! Operator error!

 
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Just received my new re-manufactured Honda alternator. I plan to use the excellent DIY resource here to install it myself. So will the battery light on dash go out when the new alternator is installed?

 
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If the alternator is installed correctly and the issue is resolved, yes.