luder4ever

hi everyone. my 93 4th gen bb4 h22a prelude keeps blowing alternators???? problem started 3months ago when i was driving the battery warning light came on but the car was still charging no problems only for a light on the dash? but two weeks ago i started the car and left it ticking over with the lights on. and while running for bot half an hour the car cut out tryed startin it but battery was dead so i put on jump leads and it started fine the the min i took off the jump leads it cut out? so left it for a while and came back again and jumped it and took off the jump leads and it stayed running so put on the mulimeter and it was charging 14.5v but when the car reached normal engine temperature it droped down to 12v and kepted droping til the car cut out so it wouldnt charge at idle but when i revd it up it charged but after a week it stoped charging totally. and have tryed 4 dif alternators since and same thin they wont charge at idle only charge above 2000rpm and after a short drive they all stoped charging totally!!!!!!! and battery light didnt turn off with any of them. and the alternators wer good came off cars that wer running? iv a new battery new belt and checked all wires with the workshop manual. all fuses are good. cheked the 4 wires on the 4-p round green plug and blk/yel (IG) has 12v with ig on also has the blu/wht (warnig light) which joins to blk/yel. the grn/whi goes to eld in fuse box unpined that wire to see was it the eld and still no charge? so all im thinkin could it be the ecu cos the red/white wire from the 4-p plug goes to the ecu on the jdm KQ model but dont know what it does there?? sum1 plzzzz help

Sparksman

lol been here.... I had a 1988 toyota ext-cab lifted pickup a few years back. The oem alternator went out, so I went to the local parts store and bought their regular reconditioned ones for like $60 bucks after the core return. The real oem replacement one or comparable one were like $200... Ended up going through a new one every week for 5 weeks... Finally found one that worked! That one lasted too.

I cant say for 100% this is the problem, just saying Ive experienced the same thing on a vehicle before. The cheap alternators were to blame for my problems, could be similar.

luder4ever

hey sparksman thanks for the reply i was thinking the same thing? but its just the way they wer grand on the cars i tok them off. prob jst get one rebuild and hope for the best? if that goes i dont know what to do. does any1 know what the red/white wire from the 4p alternator plug to the ecu does?? and could bad ground wires cause it

luder4ever

hey 5SpdH22 thanks for the reply. ya the red/white wire from the 4p alternator connector on the jdm lude goes to the ecu first then to the eld. dont knw what it does in the ecu so could it be sumthin to do with the ecu. could the eld cause it not to charge? how can i test the eld? all my fuses are good. but when i put on one of the 4 alternators on it started smokin and blow the main battery 100a fuse but that alternator was shaged.

luder4ever

just put on another alternator that tested good and the same thing agian. was charging at first only over 2000rpm but not at idle and then went totally after bot 20mins??? its diff not the alternators??? plzzzzzzzzzzzzz help any hav same problem

luder4ever

and another thing is the brake lamp warning light stays on sumtimes but brake lamps are working? could that be related to alternator problem

luder4ever

and my reverse lights stoped working when the first alternator went and bulds and switch is good wtf!!!!!!

holmesnmanny

Is it safe to assume your car is an automatic ?

What's the exact amount of voltage at idle ?

What happens to the voltage reading at idle when you turn on the headlights ?

luder4ever

hi? no its manual? at idle its 12v and keeps droping til it cuts out. and with headlights on it drops and cuts out faster

luder4ever

hi.the first 4 wer shaged when after but didnt test de newest one yet but more on likey it is shaged? but they all make a bad humming sound after thy stop charging. as far as i know the eld does throw a cel tink code 20

holmesnmanny

u need to test from the eld connector and alt connectors back to the ecu connector...something has to be open


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luder4ever

hi.iv traced all 4wires all prefect. blk/yellow and blue/white have 12v with IG on and are ground when off. the green/white put 12v to it at alternator 4p plug and gets 12v at eld plug so them 3 are good. but its de red/white wire from 4p connetor im stuck on? it goes to the ecu so could ecu be a reason it not charging

luder4ever

does any1 know what the red/white wire does at the ecu?

holmesnmanny

On the eld side the three pin connector will have reference volts on one, signal on another, and ground on the last. With the connector connected signal voltage will be 3.5 and will drop down each time you turn the lights on...first position...then second position down to 1.5 or so. You can put a paperclip into the connector with it connected and it will give you a value.

On the alternator side you will have 5 volts on one, battery voltage on the other, another will be signal voltage from the voltage regulator to the ecu, and the last will also have voltage unless the warning light is on on the dash which would give it ground instead of voltage.

Did you test for voltage on both the battery and the alternator B terminal ? They should obviously be the same. If you're not getting voltage at the B terminal at the alternator then the alt fuse must be blown.

The only way the alternator won't charge is if either the battery cable isn't connected or the ecu isn't giving it 12 volts on one of the pins at the green alt connector when the engine is running(prob blk/yellow). If it's charging but stops after the car warms up then the ecu might be bad.

luder4ever

hi. ya tested d 4p green alternator plug have 5volts on green/white ecu-eld wire 12v on black/yellow IG wire and 12v on blue/white battery warning wire? and on the eld side iv ground on one and 3.5v on another and drops to 1.5v when headlights on

holmesnmanny

What's the voltage at the B power terminal at the alternator with the car running ? Monitor at startup and as the car warms up.

Did you check the 80amp alt fuse in the engine fuse box ?

luder4ever

hey ya its 12v and drops down while the cars running. ya all fuses are prefect

holmesnmanny

Disconnect the 3 pin eld connector at the engine fuse box assembly and idle the car. It will throw a code for the eld circuit but that should make the ecu run the alternator in full output mode.

Then see what the alternator charges at.

luder4ever

hi holmesnmanny. ya i disconnected the 3pin connector under the fuse box and still only 12v? and warning light code 20 came on so pluged back in the eld 3pin plug and reseted the ecu and light went off? so i take it my eld is fine.

luder4ever

just dont understand why its not charging, cos on the 4p alternator plug wit car running it has 12v on blk/yel IG wire, 12v on blu/whi battery warning light wire, 5v on grn/whi eld wire (goes to ecu then eld), and red/whi is just signal to ecu? and on the 3pin eld plug iv 12v on one wire 5v on one and 3rd wire is earth wire.all fuses are good. iv put 5 alternators in so far and they all do the same thing charge for bot 5mins til the engine warms up and idles, then they stop charging and wont charge again? its like my car is blowing them???

crazes

honesty i happened to my coworkers accord. one of his tail light blew and gave him some complete electrical nightmare. after spark chasing for a while i told him just replace the bulb and it all went away,

DCFIVER

Replace the battery.

holmesnmanny

Sorry to ask this but you are testing at the main battery cable at the alternator ? This is the one connected to the front of the alternator with a 10mm nut over it ?

If you are and you're still getting 12v AND you're getting 12v at the battery then try this. Depin the white-green(keep in mind it's white-green not green-white) wire at the ecu. Just take off the connector open the back up and gently remove the pin from the connector, put it back and reconnect the connector to the ecu.

http://technet.ff-squad.com/wiring.obd1.htm should be pin A16 assuming you're obd1...if you're obd2 then just figure out which one is it ...it's the alternator control pin

regarding battery replacement ...while the battery could be bad I gotta think it would still charge at above 13 at the least if there wasn't another issue causing your problems

luder4ever

its a new battery? sure even if i discon the battery it should stay running if it was charging?

luder4ever

ya testin it at the alternator output nut and the battery both 12v? and ya even without a battery it should stay running if charging plus its a new battery. ya mines obd1 but a16 pin on my ecu plug is white? and my wiring was never messed with. does that wire come from the alternator or wher? and what should it do if i discon it? and if it did charge after i disconnect it, does that mean d ecu is the problem