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Discussion Starter #21
Both 17 and 18 are very incorrect.
Then why when you have a bad battery and car is running , will the lights dim or some things wont come on if all the power is coming from alternator?
Your electrical system is hooked up via the battery, while the alternator is only tied to the battery
 

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Discussion Starter #22
batteries stabilize and help limit the charging voltage. Without the battery, alternators will over volt the system. With an accurate voltmeter you can check the voltage , the voltage will go up when you disconnect the battery. It will come down when you reconnect the battery. Not a big problem in pre electronic cars but a big problem for computerized systems, electronics and most modern car systems.
 

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2006 STS V8 AWD, '95 Ford Ranger
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Current flows from the higher potential to the lower. If buss voltage is higher than battery voltage, current flows to the battery and charges it. One of the quickest checks of an automobile electrical system is to observe if the headlights flare from an idle to stepping on the gas. Flaring indicates the charging system is deficient and will not carry the load.
 

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Discussion Starter #24
Ok went out today and everything was fine , on way home I threw on rear defroster and hi beams to see how much the voltage would go down, and all of a sudden
"Battery not charging , service system " came on.
Now battery saver active.
I just replaced battery and all the numbers were great, don't understand how turning things on would cause this
Does this sound like an alternator now?
And is there a fuse for the alternator ?
 

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Get out your VOM and check voltage at the alternator terminal with the engine running.
 

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2008 STS Northstar RWD, 2000 Trans Am WS6 6 spd, 1968 LeMans convertible 6.6
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Ok went out today and everything was fine , on way home I threw on rear defroster and hi beams to see how much the voltage would go down, and all of a sudden
"Battery not charging , service system " came on.
Now battery saver active.
I just replaced battery and all the numbers were great, don't understand how turning things on would cause this
Does this sound like an alternator now?
And is there a fuse for the alternator ?
Yes sounds like an alternator.
 

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2006 STS V8 AWD, '95 Ford Ranger
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You need somebody who knows what the hell they are doing to systematically troubleshoot and analyze your problem. This long distance guessing is not going to get the job done. Being cheap gets expensive damn quick.
 

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Discussion Starter #30
You need somebody who knows what the hell they are doing to systematically troubleshoot and analyze your problem. This long distance guessing is not going to get the job done. Being cheap gets expensive damn quick.
Its not a question of being cheap,
I'm just gun shy taking it to a dealership, since they fried my air ride compressor and denied it,
So I try to get information from knowledgeable ppl like you to have information going in.
I am a union sheet metal worker and can tell you anything you need to know about hvac, but don't know what you guys know about these computer cars
 

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2006 STS V8 AWD, '95 Ford Ranger
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I'm not advocating for dealerships. Almost any area has at least one "go-to" guy for automotive electrical problems. He may be an independent or he may work in a larger shop. I'm betting that if you start asking around the same name will start popping up. I wish you luck and I apologize for coming on a little strong.
 

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To answer your question about removing the neg cable from the battery while the car is running, don't do it. Doing that will cause voltage spikes which will probably damage other electronics. It was OK in the old days but not with these newer more delicate electronics cars.
 
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2008 STS Northstar RWD, 2000 Trans Am WS6 6 spd, 1968 LeMans convertible 6.6
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So its just a coincidence this happened when I put a load on system?
Car was fine until I turned on rear defrost and hi beams.
Just replaced battery last Friday
Yes it very well could be. I have working on cars professionally for over 30 years. What sounds like (from this distance, anyway) is your alternator was barely working. Then, with a big load like rear defrost and high beams, and whatever else was on electrically, that was the final nail in the alternator coffin. I have seen many alternators with failed a failed diode or 2, it still works but barely.It needs all 6 to work properly, to change the AC it generates into DC voltage.
 

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batteries stabilize and help limit the charging voltage. Without the battery, alternators will over volt the system. With an accurate voltmeter you can check the voltage , the voltage will go up when you disconnect the battery. It will come down when you reconnect the battery. Not a big problem in pre electronic cars but a big problem for computerized systems, electronics and most modern car systems.
Batteries do no limit charging voltage.They act like an electrical spring to help keep current steady in all circuits in a car. Voltage may go up when the battery is disconnected, but the alternator is still regulated to usually no more that a 15V output either by the PCM or internally regulated in the alternator and will not "over volt" anything unless it is defective.

The only reason the alternator would go higher with the battery disconnected on a running car is because the battery could be absorbing some of the current if it is recharging. But if an alternator is outputting more that 15.3 volts with no battery, it is either not being regulated by the PCM or its' internal regulator has failed.
 

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Discussion Starter #35
I had the alternator rebuilt.
They said it was only putting out 11v .
My problem now with this is,
After they put rebuilt one in the voltage would be around 13.7 but then go down as low as 12.9-13
And 4hey said that is normal for these cars .
Battery is still at 12.6, however,
I took a long drive on Friday and twice the battery light came on for a couple of seconds saying system not charging.Then would come back on line That isn't right !
They say there must be something wrong with computer.
Also when on highway it completely stalled "starting disabled throttle problem "
So took to dealership and they can't get it to act up, so they're saying nothings wrong, grrrrr
Told them it spewed out p0601 code.
Don't know if I should just tell them to flash or replace pcm
But you would think they should know the cause.
 

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Yes very frustrating indeed. If I monitor the voltage on my STS, it will go as low as 12.9, normal for this and some other cars. However, it the system not charging message comes on, yeah you have an issue. No sure what the voltage parameter for that warning message to be, probably less than 12.4 for over a minute. Can you see the actual voltage when you get that message? Could be a defective new/rebuilt alternator, do you know how many times in my career I've had that happen. Makes me pull the rest of my hair out, wondering what I'm missing in my diagnosis. I've had a car with 4(!) defective alternators! the original that the car came in the shop with, plus 3 others that were bad out of the box before I got a good one.

P0601, could be a throttle body problem like others have mentioned, but I've never seen that. It is usually a bad PCM, and pretty sure a flash would not fix it.
 

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Discussion Starter #37
Shop said they won't do anything until alternator fails even though it is showing signs,which doesn't help me 30+ miles away when it does and yes can see v9ltage and it was 13.4 when got warning for a split second , it was about to go into saver mode
 

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So it sounds like your alternator is ok. Some other issue, tricky to find it. I'd be looking carefully at all alternator wiring, very time consuming. Wiggle wires, check connections at the PCM, etc.
 

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Discussion Starter #39
When the other alternator failed it never came back on line, also never once saw that message on DIC ever, until it failed , so I'm assuming it's the rebuilt, because never had issues before
 
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