Alternator problems

[fatboy1185]

New alternator, new battery, both tested out good. When I first got the car, I was told the alternator was bad. Well I put a new battery in, and drove it for 5 months with no problems. Then it stopped charging. Put a different used alternator in it, and it worked fine for another couple of months. Then it stopped charging again.

So, after putting new alternator in, and new battery, it still wouldn't charge. The alternator just wasn't putting out any power. So, after checking out the ECU, I noticed the vtec pressure switch and vtec solenoid were NOT plugged into the ECU. So, after hooking those up, I tested the alternator with the volt meter, and it WORKED!! The alternator was putting out 14v and the battery was getting 14v.

2 days later, went out to start the car, battery was dead. Jumped it, tested alternator with volt meter, 12.4 volts Any ideas? What would the vtec pressure and solenoid have to do with the alternator? Is there any other wiring I should check? The alternator IS recieving 12v from the ignition power source.

[Shag Wagon]

Have you checked the wire that goes from the alt to the fuse block for ohms? I had that problem on my cadillac and I had to replace the alt cable. When I tested it, it read like a million ohms hahaa.

[fatboy1185]

Have you checked the wire that goes from the alt to the fuse block for ohms? I had that problem on my cadillac and I had to replace the alt cable. When I tested it, it read like a million ohms hahaa.

I think that is called the ELD (electrical load detector)unit? I just went out and checked it, according to write up below, and it checked out good. Started the car, checked the alternator with the multimeter, and it's working again. So there has to be a loose wire somewhere or something, that is causing the alternator to cut in and out:

The ECU does talk to the ELD. Basically the ELD tells the ECU that its now going into highoutput mode and to please idle the car a lil higher (ever notice how you turn your headlights on and then the idle picks up a tad? Thats why... to compensate for the extra load on the alternator).

Electrical troubleshooting says: ELD is a code 20 (but you're not seeing any codes). Tesing proceedures for a ELD:

1. disconnet the 3 pin ELD connector on the drivers front side of the fuse box (underhood).

2. with the ignition switch ON (car not running) there should be battery voltage between the black & yellow (+) and the black (-) wire terminals.

3. if there is no voltage check for:
- an open in the black & yellow wire between the dash fuse box and under-hood fuse box.
- poor ground

* if there is voltage goto step 4.

4. Check for voltage between the green & red wire terminal and the body of the car with the ignition switch still on.. There should be approxemetly 5 volts.

* if the voltage is as specified goto step 5.

5. check the voltage between the green & red terminal and body ground same as step 4 except with the headlights (low beam) on. there should be approximately 2 volts.

- if te voltage is not as specified replace the relay/fuse box. ELD is not available seperatly.

- if the voltage is as specified ELD unit is ok.

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if that check out OK its either a shot wire, bad alternator or bad ECU.

[AndyD]

How's your ground wire to the battery?

You sure the batter was dead each time? My mom had a similar issue. She thought the battery was dead. It turned out to be a bad relay.

[cb7remnant]

not totally sure if cb's have one but some cars have a separate computer monitoring the alt and if you overload it fries and your alt will not charge the battery any more *not sure if CB7s have one* guy at my school killed his by trying to jump start another car, he left the jumper wires connected when the other car attempted to start and it overloaded his.

[fatboy1185]

How's your ground wire to the battery?

You sure the batter was dead each time? My mom had a similar issue. She thought the battery was dead. It turned out to be a bad relay.

Ground wire is good. The alternator isn't putting out a lot of power. With the car running, it's reading about 12.5.

not totally sure if cb's have one but some cars have a separate computer monitoring the alt and if you overload it fries and your alt will not charge the battery any more *not sure if CB7s have one* guy at my school killed his by trying to jump start another car, he left the jumper wires connected when the other car attempted to start and it overloaded his.

Yes, the ELD, I already checked it.

[fatboy1185]

Any other ideas?

[Losiracer2]

is that big plug that connects to the alternator on there securely? mine would cut in/out b/c that stupid plastic clip was broken, not ensuring a good connection. I eventually took a small ziptie to it and its holding fine.

[fatboy1185]

is that big plug that connects to the alternator on there securely? mine would cut in/out b/c that stupid plastic clip was broken, not ensuring a good connection. I eventually took a small ziptie to it and its holding fine.

Yes it is. I'm redoing the t-stat ground now, I'm running out of ideas.

[wed3k]

full field it.

[fatboy1185]

full field it.

What does that mean.

[wed3k]

you test the alternator's ability to produce amperage.

there's a hole on the connector side of the alternator and it should be right below the connector. you need to stick a screwdriver in there and monitor the voltage. dont let the voltage get above 18v otherwise shit will blow up.

test your charge warning light...my dad's gauge setup went out on his lexus and it prevented the alternator from charging as well.

do you have a manual? all this is in the manual, im looking at it right now.

[fatboy1185]

I looked and didn't see any hole under the plug on the alternator.

[fatboy1185]

Went through a lot of the wiring, checked it all out, looked fine to me. Added a few more grounds, checked battery, 11.1 volts. Started car, 12.5 volts, no matter what the rpm's were at.

[fatboy1185]

What the mother f.