Jump to content
SAU Community

Recommended Posts

two days ago the battery light came on in my car. Checked the voltage and it looked like the car was running on the battery only. I have just installed a replacement alternator and the issue is still there that the battery light is on and the car isnt making more than 12v.

If you run the car with the jumper leads connected to another running car it idles/revs fine if you disconnect it the fuel pressure drops and the car leans out (i assume thats to do with voltage)

do you think i have gotten a faulty altternator or is there some other electrical issue that people know of that would stop the alternator making any current?

Link to comment
https://www.sau.com.au/forums/topic/300654-alternator-issue/
Share on other sites

could it be a battery issue where the battery is what is stopping it from increasing the voltage?

there is a way to check this although it isn't the best thing to do. start the car with the battery connected, then disconnect the battery and check the voltage of the alternator then connect the battery again. only problem is that there is a small chance that the extra voltage from the alternator can damage the ecu, but i have seen this done before when jump starting a car without jumper leads.

could it be a battery issue where the battery is what is stopping it from increasing the voltage?

there is a way to check this although it isn't the best thing to do. start the car with the battery connected, then disconnect the battery and check the voltage of the alternator then connect the battery again. only problem is that there is a small chance that the extra voltage from the alternator can damage the ecu, but i have seen this done before when jump starting a car without jumper leads.

Do not do this. Easily possible to destroy all electronics on your car and cost you a lot of money in repairs. That was an old trick before cars had electronics, to test if the alternator was working. The battery acts as a large capacitor and supresses voltage surges through the electrical system. Most EFI cars have enough of an idle current draw to keep a regulated alternator from spiking sharply but do you really want to chance it? Have you ever tried to switch on cruise control while your driven wheels were in the air? The reg in the alternator behaves very similar. Massive over and undershoots without the battery attached.

Nissan alternators needs 2 things to properly charge a battery. A voltage reference input and an excite wire. The VRef wire should be attached to the battery positive to measure how much voltage drop there is in the charge wire, to keep the battery fully charged. The excite wire provides a tiny amount of current though the charge light to energize the alternator as it contains no magnets. The excite wire is clearly working (white / red stripe) so check you have 12v on the other wire (i forget the color) on the 2 pin connector.

edit - the white/red wire should be close to zero volts with the engine off, then up to 12v with it running. The other wire on thta connector should have 12v on it all the time.

If the white/red wire still has close to zero volts with the engine running and the other wire has 12v, you have a faulty alternator.

Edited by Bozz

yeah I would have guessed that...

I've had the battery terminals drop off the batery a few times (the negative) and nothing went wrong, besides a quick drop in voltage whenever I turned the lights on... But my alternator is in pretty good nick, I have no plans of needing to change it anytime soon...

The positive terminal hasn't come off since I put the new battery in there about 2 years ago...

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • My take on gg2 48mm, 54mm, 58mm, and 62mm compressor map for same size compressor vs gg1 : All gg2 only outflow gg1 above 20 psi. As all g gen 2 surge line at lower left of comp map move to the right, all gg2 sacrifice spool vs same size gg1, surge line move to the right worst for 54mm gg2. So for same size compressor if you want best response, use gg1, if you want max hp at >20psi use gg2 but you will be laggier vs same size gg1. Max compressor efficiency drops to max 75% on all gg2 vs max 76%-80% of same size gg1. Iirc lower efficiency means hotter iat less dense air so lower hp at same operating point of comp map. Also curious why gg2 is mapped to lower max rpm vs same size gg1 (only 48mm size both gg1 gg2 mapped to same rpm) : 54mm gg1 165,000 rpm  vs  gg2 160,000 rpm. 58mm gg1 150,000 rpm vs gg2 140,000rpm. 62mm gg1 145,000 rpm vs gg2 140,000 rpm. If gg2 can safely spin to gg1 rpm then they can flow a bit more than as mapped. Good thing that all gg 2 interchange compressor and turbine housings with same size gg 1. So gg1 owners can buy gg2 chra only if planning to boost >20psi.
    • My stuff is all with Shannon's, granted, I don't really have imports I'm driving on the road, however, I've had multiple cars at the same time with them. Presently we have the Landcruiser on laid up cover, Sarah's Kluger on full cover, and the house insured. About 18 months ago Sarah wrote her Subaru Liberty GTB off, insured with Shannon's, and the payout, and buy back of the wreck was super quick. In 2020 we had the VF Commodore totalled in a major hailstorm. Storm was on the Saturday, I called on the Sunday and lodged it, vehicle was towed on Tuesday night, assessment team called on Wednesday to say it was a total loss and get payout details, money was in the bank on Thursday morning. Have had a few other claims both at fault, and not at fault, over the years, and never had an issue with them.   Funnily enough, they're also the cheapest insurer I find for things like Sarah's Kluger.   I will say I'm less impressed dealing with them lately around "the experience", as a lot of their staff that you deal with aren't car enthusiasts. Shannon's has a much more main stream feel ever since they decided to become "big corporate", laid a heap of staff off, and then hired a bunch of non enthusiasts. At the same time they've been making a push to be less "call us and we'll personally have someone who cares help" to "hey, this computer can do stuff for you" and are trying to get more square pegs to fit round holes. (That's just the vibe I get from them). Again, have had no issues with claims with them, but get a bit of a "less personal" feel from them.
    • A thing I wasn’t happy with with enthusiast was during the initial phone call they told me they’d insure it for 130k but needed photos.   I then sent them photos and they told me $80k as there were other cars either similar modifications available for around that price, I told them to send me the links to said cars so that I can buy them. i then sent the modification list with prices of the parts (no labor) and the price then came to 115k, which is still shy of the 130 that was agreed in the initial phone call 
    • Ask me a bit later this week before payday
    • I agree that delayed payment probably isn't the most suitable solution. It seems a solid complete transaction would be best. As I wouldn't be using this sale as a line of credit that would typically earn interest, we can probably arrange a much cleaner single transaction deal. I can do $92.52 today. Would you prefer EFT, or Cash on Pickup?  😛
×
×
  • Create New...