Alternator problem and what is this plug?

  • #1

    Alternator problem and what is this plug?

    So i have been having problems the past week with only have my charging system going to around 11..3-11.9v. I changed the battery that was known good from my other z and i still had the same problem. I then upgraded the alternator with a maxima one (i got from a user here i guess im not sure if it works he claimed it did) and i am still getting the same problem. So thats 2 batteries and 2 alternators and the same low volts problem any other ideas? I am bringing the alternators in tomorrow to get tested and i will also double check my grounds.


    Also while I was changing my alternator i found this plug.

    http://i289.photobucket.com/albums/ll23 … 212552.jpg

    http://i289.photobucket.com/albums/ll23 … 212604.jpg

    what the heck is it? I noticed on my z when i turn the key to the on position right before the last turn to start my oil light comes on and when i start it it goes away.
    86 NA
    87 Turbo
    Member of the "zetto sun-ichi" group


    Local MN car forum/club anyone welcome..... fivezeroseven.net join!
  • #2
    That plug is for the knock sensor.

    The oil light turning on then off once you start the car is normal.
    If you lost oil pressure while you were driving the light is supposed to turn on.
    Shiro #443

  • #3
    ok thanks ill have to figure out where that plugs into then unless someone has a clear picture of where it goes (i have a vg33)
    86 NA
    87 Turbo
    Member of the "zetto sun-ichi" group


    Local MN car forum/club anyone welcome..... fivezeroseven.net join!
  • #4
    knock sensor or detonation sensor?

    if its a vg33 block the knock sensor is under the lower intake manifold under the water pipes in the block and its a 2 pin plug.

    that plug looks like it goes right by the oil pressure sending unit detonation sensor on the stock motor…

    did you get that alternator tested before you put it in?

    check the plug that goes into the alternator, one of those wires (check fsm) is the sense wire and if its not connected or plugged in correctly the atlernator will not charge.
    My Build Thread
  • #5
    ok thanks for the responses and no i didnt test it before i put it in like i should of took the members word for it when i bought it. I will pull it out and get my old alt and the new one tested when im off work.

    So i think it is the z31 wireharness with the vg33 engine so ill look around for the denation sensor because theres no way that cord will reach up any higher than the headers. The cord is only like 2-3" long if that. I will look for the detonation sensor or is that not on the vg33?
    86 NA
    87 Turbo
    Member of the "zetto sun-ichi" group


    Local MN car forum/club anyone welcome..... fivezeroseven.net join!
  • #6
    don't worry about the knock sensor, it threads into the block near the engine mount, useless by many members opinions as it works in part throttle and cruise situations, the signal is ignored during boost.[attachment=0:2b65cc1g]DSC04124 (Large).JPG[/attachment:2b65cc1g]
    Denis Gagné
    aka VGwagon
    GM specialized licensed technician

    69 510 VG30 powered wagon
    73 240z shell VG30et in progress
    86 300zx NA2T
  • #7
    alright thanks that is a great picture! Ill see if i can get it pluged in if not i wont worry about it.


    So if i come home after getting my alternators tested and they test fine and my batteries are good and the belt is new and tight what is left just the bad ground or something in the wires?
    86 NA
    87 Turbo
    Member of the "zetto sun-ichi" group


    Local MN car forum/club anyone welcome..... fivezeroseven.net join!
  • #8
    update. I got my orginal 70 amp alt tested on my lunch break…one place said it had 14.6 volts the next place said it was getting 11.5 volts (this is what i get when i take a volt meter to my terminals when its in the car). I am going to go to another place and get it tested when im off work im hoping it bad and not something else.
    86 NA
    87 Turbo
    Member of the "zetto sun-ichi" group


    Local MN car forum/club anyone welcome..... fivezeroseven.net join!
  • #9
    went and bought a new maxima alternator and im still only pulling 13.7v so i might try and rewire it all and see if that helps im hopign i have a bad wire or something i have changed 3 alternators and 2 batterys and a new belt and this is the best i can get it.
    86 NA
    87 Turbo
    Member of the "zetto sun-ichi" group


    Local MN car forum/club anyone welcome..... fivezeroseven.net join!