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Bonneville GXP/ Northstar Powered Cars Discuss your Bonneville GXP and/or any other Northstar powered Olds or Cadillac... Including the 3.5L Twin Cam V6 (Short Star ) 4.0L and 4.6L Northstar V8's. Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 05-04-2011, 08:26 PM   #11
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Yeah, got hit on the driver side front fender. The alternator went out almost the next day. Hmm. I didn't get hit very hard though, but I suppose anything is possible. Autozone ran the diagnostic and it showed batt and alternator was bad. Can a bad ground or other electrical problem cause it to show bad alternator? Or is the test fairly conclusive. I consider myself a fairly competent shade tree mechanic, but I dread the thought of tackling this Northstar. My experience thus far has been with older Chevy V-8'*, small and big, and the 3800 and 4300 V-6'*. none of which are remotely near the N* in terms of complexity or general difficulty to work on.
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Old 05-04-2011, 09:01 PM   #12
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It'* really hard to answer. Bad ground could should low voltage but that would make the alternator "if good" ramp up when running.. A short in wiring in that fender area could cause a low voltage reading and take out the alternator. Given the accident, conclusive isn't going to be an online call or remedy.

Given the really low voltage bad alternator likely. But what caused it is in doubt. Maybe time, maybe bad ground, maybe accident. I would check the damage area from inside/underneath and make sure there isnt a short. CHeck that ground connection to the body under the rear seat and battery connections. If all this is good and low voltage remains, yeah alternators gone. When replacing it I would make sure the battery is fully charged, connection are good, and watch to see if voltage reads higher than a lower-mad 14.x'*. If you get into 15+ with a good battery it'* time to shut er down and really look for a short.
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Old 05-04-2011, 10:11 PM   #13
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Well, at this point I'm just going to go ahead and replace the alternator. I already ordered a replacement from rockauto.com, and its going in now no matter what. It took me about 2.5 hours to take the electric fans out and remove the underneath engine splash guard lol. Though I could do it much quicker the 2nd time. I can finally see the alternator.

If I find the engineers who designed this stuff I'm going to punch him. I was about to take the belt off, but thought I'd better wait until tomorrow since I have to go work a night shift now. I hope I am able to get the old unit out tomorrow afternoon so I'm ready to install the new unit when it arrives. I have an appointment at the body sop next week, and a 500 mile road trip to take in June that had in mind when I bought this thing.

If this thing passes a bench test when I get it out I'm going to cry. In my truck I could have had an alternator out in 10 minutes
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Old 05-05-2011, 04:09 AM   #14
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another thing you can do is test the power at the alternator itself, but might as well you have it ordered just replace it. less parts to replace in the future lol

yeah pretty much it can be removed in 10 minutes on any car, except our stupidstar engine
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Old 05-05-2011, 06:05 PM   #15
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Almost there, got the front two bolts off, but I'll be damned if I can even see and touch the bolts on the back, let alone get a tool back there. Might as well be held together by black magic. If I ever meet the guy who designed this engine, it will be a day he wont ever forget.
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Old 05-05-2011, 09:06 PM   #16
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ok, it actually wasn't that bad. The 3rd bolt was right on the front of the engine, plain as day and easy to remove. Maneuvering the alt. out was tricky, but not too difficult. I could do the whole thing again in under two hours now that I know how. Took the old unit to autozone for bench testing, and it failed, showing a bad regulator. The new on shipped from rockauto today, so in the meantime I guess I'll put on these red overlays I ordered
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Old 05-05-2011, 11:51 PM   #17
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Quote:
Originally Posted by SAMzGXP View Post
you have 2 way of testing an alternator
#1, remove the red cable off the battery after starting the car, and see if the car shuts off or if starts hesitating
#2, put a volt meter on your batter before starting your car, it should read 12~v or so. once you start the car and shes running at idle it should jump up to 14 or little under. my GXP was at 14.2 i think.

Sad to hear you're having such a shitty luck, but to me it sounds more like a loose connection. check all your cables and grounds

On a side note, #1 above is not a good idea or a valid test for an alternator, it was back in the day of generators.
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Old 05-06-2011, 02:24 AM   #18
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It worked on alternators too when the voltage regulator was separate. But these days they are solid state/onboard the altenator. Some will the "test", alot won't. Not sure about ours, but alot of them will burn out the onboard voltage regulator circuit/chip as soon as you pull the positive off. Ask me why I know...
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Old 05-07-2011, 01:27 AM   #19
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Quote:
Originally Posted by GXP Venom View Post
It worked on alternators too when the voltage regulator was separate. But these days they are solid state/onboard the altenator. Some will the "test", alot won't. Not sure about ours, but alot of them will burn out the onboard voltage regulator circuit/chip as soon as you pull the positive off. Ask me why I know...

Sorry but this has never been correct with alternators, it has been an old wives tale for many years, I was in the parts business for many years, including when cars had generators and heard this tale regularly. Below is from the Wiki:

EDIT: DO NOT EVER DO THIS ON A MODERN VEHICLE. DOING SO CAN DESTROY A WORKING ALTERNATOR, AND CREATE A VOLTAGE SPIKE THAT CAN DAMAGE ANY AND ALL SENSITIVE ELECTRICAL EQUIPMENT ON THE VEHICLE. PEOPLE WHO SUGGEST THIS METHOD ARE RELYING ON OUTDATED METHODS OF TESTING GOING BACK TO WHEN CARS RAN GENERATORS, HAD MECHANICAL REGULATORS, AND NO SENSITIVE ELECTRONICS.
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Old 05-08-2011, 12:37 AM   #20
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Ok, got the part in today from Rockauto. The alternator arrived at 3:30, and by 5:00 I was taking it on its test drive after replacing the alternator AND changing oil. Now that I know how, I have to say that the 3 bolts were actually fairly easy to get to, and removing and reinstalling the electric fans was probobally the hardest part, and thats just because I didn't remove the radiator. I took some pics, and I am going to do a write up to help anyone else who needs it.
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