Ok here goes. 1991 honda accord LX 2.2. 5 speed
New battery and new drive belt, replaced alternator with a know good unit.
At idle with full load (lights on, door open, heater fan on high) voltage climbs to around 14.7
If i rev the engine the voltage drops to less than 12.5 (battery voltage is 12.7 with engine off)
cleaned and chaecked all cable, check all fuses, have batt voltage at black yellow wire at alternator.
checked visually and with meter all fuses under hood and inside car.
Battery/charge light does NOT come on at all even at start up/diagnostic check. Grounding blue white wire at alternator does not light the lamp either.
Followed the poorly written trouble shooting guide in Haynes manual. It appears to be the "Intergrated control unit" above the kick panel. This appears to be the only USA mad part on the car.

 

Are you haveing problems with the battery going dead? The ecu controls the alternator, it doesn't run full blast all the time.

 

acts like a bad voltage regulator ..

have a shop do a charging system test .. I assume you DID NOT use a Honda alternator ??

 

Yes the battery goes dead after driving for a while. the car will run if i shut it off the battery is dead and will not start until recharged. The replacement was a Nindenso (sp) alterantor out of another accord that was running, But had trans problems, nice to have friends. The puzzling thing is that little battery light does not come on. I plan on pulling the dash among other things today to check the bulb.
The ECU was mentioned, as a ford guy the ECU is the computer that controls the engine to me. I was refering to the control box above the fuse panel called and Integrated control unit in the manual. not the computer under the passenger side toe board.
As for charging test voltage is fine at idle, it is as rev's increase that the voltage drops.

 

Latest update, and hour later.
Okay did some tests and found that the passive seat belt motors had a continiuos draw. I pulled those two fuses under the hood. now the car charges around 14.3 volts at idle, and the voltage doesn't drop as I rev the engine. Sucess ......Yeah right. If i load the alternator (turn on heater/ac fan or headlights) the voltage drops again. Almost like the damn ICU or load detecter is wired backwards. I guess it still could be the used alternator. I grounded the blue white wire from the alt and still no battery light, gonna pull the dash next and check the bulb.
Any where else to turn before i blow $100 bucks on a rebuilt honda alt??

 

next update. The dash bulb good.. so problem is elsewhere right? I guess signal is not getting from alt to ICU to bulb and back...Likely place to check? Or just start probing wires?
Any help at all at this point would be most appreciated. Don't mind blowing the $100 on alt if it will fix problem. but at this point everything seems to point elsewhere than the ALT.

 

Well still looking. no battery voltage at white/green wire on alt.

 

can't trace white/green wire. relay mentioned in repair manual i can't find. Engine compartment very tite for big guy like me.

 

I'd have a charging system test done as Desert mentioned. Also if that manual is a pain the rear you can download a service manual for free.

http://hondatech.info/downloads/Auto/Manuals/Accord/

 

i tested the charging system. hence the post with voltages mentioned.
trouble shooting steps lead me to white/green wire not having bat voltage (engerizez alt?)
Okay took the alt out and went to the auto store. Put in on the machine. It is fine!! full voltage and amp load. Last test is to disconnect the sensor wire white orange? If the system charges with out this wire??
So back to wiring and or sensors load dector what not. Load center is integrated into fuse box, under hood?? is it replaceable from underneath? Does the car have to go to honda for service? What are my options at this point?