Charging system is not generating 14.5 volts. New battery, new alternator, 14.5 volts from alternator, only 12.5 at the battery, ? bad wire, ECU limiting charging voltage? Any ideas or solutions?

 

 

I am thinking I should run a new wire from the alternator output directly to the fuse box going into the battery to bypass the wire harness , check and replace any suspect fuse box connections and see if voltage is restored to 14.5 volts to the battery. Dealing with possible unknown resistance in existing wiring becomes a speculative process.

Still wondering if ECU could be regulating alt output somewhere along the wire to the fuse box and battery? We definitely saw 14.5 volts output from alternator to grounded meter probe to the engine block. Just need it to make it to the battery at 14.5 volts.

 

Yes the ECU switches the alternator between normal and low charging depending on the operating conditions. It's the primary function of the ELD (electronic load detector) built into the underhood fuse box. It allows the ECU to monitor the electrical load on the system at any given time. This should be detailed in the OEM Integra service manual. I remember reading about it in my old 89 CRX helms manual after observing exactly the same thing while driving.

 

Thanks 94eg!
Is the ELD able to be tested, is it programmable and/or repairable through the ecu; or did you replace with a new one from Acura?

How did you resolve your malfunction?

Thanks
art

 

I don't remember how to test it (check the shop manual). I just replaced my underhood fuse box and it behaved exactly the same. My problem was actually turned out to be a bum alternator (fresh from O'Reilly) that would cause the battery light to come on whenever it went into low-charge mode.

 

With all the ideas I went to a local Advance store to check voltages and test output, a helpful manager and i tested alternator output @ 14.5. Acura parts guy in Delray suggested it may be a ground problem. We checked a new grounding strap voltage went up .25 to 12.9, looked promising. We installed a cable from the battery negative (ground) to the distributor housing atop the engine and voila we had a steady 14.33 volts. Car is running better than ever. Thanks to all for the helpful input.