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Ok I did some tests this morning….
i tested the battery voltage before starting the car (battery had some surface charge). It was 12.6 volts. I then started the car and it was 13.99 volts between the battery posts. I then turned all accessories on, with car running. It was 14.00 volts. I then raised the RPM’s with engine loaded and got 14 volts again.
I testing for leaking amps. With the engine off, I disconnected the positive feed to the alternator. I placed the DVOM on amp scale and place leads between the alternator terminal and the wire. I got 0 amps.
I did a diode check by setting DVOM on diode. I put the positive lead of meter on the alternator terminal and the negative lead to alternator case. I got no reading this way. I then switched the leads and got 375. I think this means that the diode is good???
I then checked the ripple voltage. From what I read, this also checks for bad diodes… I set meter to the 200ACV scale. I put the negative lead of meter to chassis ground (I did this test twice, I used the negative battery post the second time and got the same results). I put the positive lead of meter on the battery terminal on the back of the alternator. I got 30.5 ACV. From what I hear that measurement is supposed to be around 0.5 VAC. So, is this test conclusive enough to say that I have a bad diode in the alternator?
Ok I did some tests this morning….
i tested the battery voltage before starting the car (battery had some surface charge). It was 12.6 volts. I then started the car and it was 13.99 volts between the battery posts. I then turned all accessories on, with car running. It was 14.00 volts. I then raised the RPM’s with engine loaded and got 14 volts again.
I testing for leaking amps. With the engine off, I disconnected the positive feed to the alternator. I placed the DVOM on amp scale and place leads between the alternator terminal and the wire. I got 0 amps.
I did a diode check by setting DVOM on diode. I put the positive lead of meter on the alternator terminal and the negative lead to alternator case. I got no reading this way. I then switched the leads and got 375. I think this means that the diode is good???
I then checked the ripple voltage. From what I read, this also checks for bad diodes… I set meter to the 200ACV scale. I put the negative lead of meter to chassis ground (I did this test twice, I used the negative battery post the second time and got the same results). I put the positive lead of meter on the battery terminal on the back of the alternator. I got 30.5 ACV. From what I hear that measurement is supposed to be around 0.5 VAC. So, is this test conclusive enough to say that I have a bad diode in the alternator?
I bought a cheap alternator from ebay. I thought it would be ok since it was new and not rebuilt. I should’ve just bought an OEM one. I took out the 30 amp fuse that went to the alternator and the battery still drained overnight. I think, though, that the alternator can still backflow current back to the battery even with that fuse out. But, I think if I disconnect the alternator connector overnight, it would not drain the battery anymore. I will disconnect the alternator tonight and check the battery voltage in the morning and see if the drain is gone.
Anyways, I can tell something’s wrong with my car because the new alternator whines as did the old one. Every time I check the battery in the morning, it’s 12.20 volts, and that was with both the old and new battery. The lights dim alot, like when it’s at night and I am rolling the window up, they dim alot. The car will still run and everything and it will charge perfectly at anything above idle. But, when it’s at idle, it doesn’t charge worth a crap and at night the battery drains. Never has the battery drained so much, though, that I couldn’t start it in the morning.
I bought a cheap alternator from ebay. I thought it would be ok since it was new and not rebuilt. I should’ve just bought an OEM one. I took out the 30 amp fuse that went to the alternator and the battery still drained overnight. I think, though, that the alternator can still backflow current back to the battery even with that fuse out. But, I think if I disconnect the alternator connector overnight, it would not drain the battery anymore. I will disconnect the alternator tonight and check the battery voltage in the morning and see if the drain is gone.
Anyways, I can tell something’s wrong with my car because the new alternator whines as did the old one. Every time I check the battery in the morning, it’s 12.20 volts, and that was with both the old and new battery. The lights dim alot, like when it’s at night and I am rolling the window up, they dim alot. The car will still run and everything and it will charge perfectly at anything above idle. But, when it’s at idle, it doesn’t charge worth a crap and at night the battery drains. Never has the battery drained so much, though, that I couldn’t start it in the morning.
I read the link above. My mega amp fuse is good. The alternator charges the battery when the car is on. It’s only that when the car is off that the alternator is killing the battery. I will do a definite check to make sure the diode is dead tomorrow morning. My question is why is my car killing alternator diodes?
I read the link above. My mega amp fuse is good. The alternator charges the battery when the car is on. It’s only that when the car is off that the alternator is killing the battery. I will do a definite check to make sure the diode is dead tomorrow morning. My question is why is my car killing alternator diodes?
I’ve already found the drain. It’s the alternator. From what I am hearing it’s probably a bad diode in the alternator. The thing is this very same thing happened to the old alternator. Is there anything in particular that can kill alternator diodes? And until I get another alternator, can I just go ahead and take out the 30 amp fuse to the alternator so it doesn’t drain the battery overnight?
I’ve already found the drain. It’s the alternator. From what I am hearing it’s probably a bad diode in the alternator. The thing is this very same thing happened to the old alternator. Is there anything in particular that can kill alternator diodes? And until I get another alternator, can I just go ahead and take out the 30 amp fuse to the alternator so it doesn’t drain the battery overnight?
Ok I found out what is draining the battery when the car is off. It’s the alternator fuse. It’s a 30 amp fuse in the engine compartment fuse box. My question….Why and how is the alternator draining the battery? Also, how do I go about troubleshooting this problem? Thanks for the feedback!
Ok I found out what is draining the battery when the car is off. It’s the alternator fuse. It’s a 30 amp fuse in the engine compartment fuse box. My question….Why and how is the alternator draining the battery? Also, how do I go about troubleshooting this problem? Thanks for the feedback!
My fuel trims stay close to 0% while driving. I’m sure I got a vacuum leak somewhere. I’ve replaced pretty much everything but the lower intake manifold gasket to correct the leak. But, my question was why the big difference in LTFT between idling in drive and idling in park? Why would the car go even leaner as soon as I put it into drive?
I’ve been watching Eric’s videos for a long time… They are very informative… He’s one of a kind. I’ve learned so much from watching.
I also have a question about my alternator and/or battery. I watched the video about diagnosing alternator faults and I am wondering if my alternator and/or battery is dying on me. I did some testing this morning. The ambient temperature was 48F. I tested battery voltage before I started the car. It was 12.29 volts.
With the car running at idle, with no load. Voltage was anywhere from 14.14 volts to 14.29 volts. The voltage seemed to constantly fluctuate between those voltages.
Then I turned all accessories on and at idle it dropped down to 11.72 volts. It stayed between 11.72 volts and 11.78 volts.
Then with all accessories on with engine rpms around 2500rpms, the voltage went to 13.72 and stayed very close to that number.
Now with this information I think the battery is getting weak and alternator may be going too. According to the video the voltage shouldn’t be that low at idle with all accesories on. But a few other people told me that since the voltage did go up when I raised the rpm up to 2,000rpm’s, that the alternator was okay. So, what do you guys think? I also checked positive side and ground side and everything was good there.
My fuel trims stay close to 0% while driving. I’m sure I got a vacuum leak somewhere. I’ve replaced pretty much everything but the lower intake manifold gasket to correct the leak. But, my question was why the big difference in LTFT between idling in drive and idling in park? Why would the car go even leaner as soon as I put it into drive?
I’ve been watching Eric’s videos for a long time… They are very informative… He’s one of a kind. I’ve learned so much from watching.
I also have a question about my alternator and/or battery. I watched the video about diagnosing alternator faults and I am wondering if my alternator and/or battery is dying on me. I did some testing this morning. The ambient temperature was 48F. I tested battery voltage before I started the car. It was 12.29 volts.
With the car running at idle, with no load. Voltage was anywhere from 14.14 volts to 14.29 volts. The voltage seemed to constantly fluctuate between those voltages.
Then I turned all accessories on and at idle it dropped down to 11.72 volts. It stayed between 11.72 volts and 11.78 volts.
Then with all accessories on with engine rpms around 2500rpms, the voltage went to 13.72 and stayed very close to that number.
Now with this information I think the battery is getting weak and alternator may be going too. According to the video the voltage shouldn’t be that low at idle with all accesories on. But a few other people told me that since the voltage did go up when I raised the rpm up to 2,000rpm’s, that the alternator was okay. So, what do you guys think? I also checked positive side and ground side and everything was good there.