Sub Tank Switch Wiring Diagram question

Discussion in '80-Series Tech' started by Romer, Mar 8, 2007.

  1. Romer

    Romer fatherofdaughterofromer Moderator

    Messages:
    9,370
    Location:
    Centennial, Colorado
    I have the Toyota OEM Sub tank Switch and Georges ECU. I can see from George's ECU schematic where two connections from the switch go. Can't find the list of switch pinouts or the wiring of the other pins anywhere. Need to define this so I can build the harness connecting the ECU to the switch and the rest of the harness.
  2. cpg

    cpg

    Messages:
    677
    Location:
    Livermore , Ca.
    Here are my notes on it.

    “2” 14 Gauge wires from relay to pump ( www.apeusa.com pump gsl391 with 30 amp relay)
    Pump Red Positive
    Yellow Ground

    “3” Wires from sending unit to ECU Kick Panel console. 16 gauge.
    White Black = Ground
    Yellow Red = Fuel Gage
    Yellow Green = Empty / Shut off

    White/black
    Subtank switch



    ECU top right and down.

    Sub Tank Switch pin 4 ( Black )
    Pos. coil relay (Green) Relay 86 pos coil
    Sub tank sending unit empty yellow green from sub tank (Yellow from ECU Black from tank)
    Sub Tank Switch pin 9
    Sub Tank Switch pin 3 / Ground and Relay 85 neg coil
    Sub Tank Switch pin 6

    12Volts (white wire from ECU)


    Sub Tank Switch
    90980-10801 Sub Tank Female Connector


    Pin 2 Positive ash tray light (Red) Solid Green
    Pin 1 Negative ash tray light (Green) White Green Tracer
    Pin 3 Ground and ECU (Green) and Relay 85

    Pin 4 ECU (Black)
    Pin 6 ECU (Brown) SW1A
    Pin 9 ECU pump (Red) SW1B

    Rocker Switch for Gauge
    Yellow Red DS Kick Panel 22 Pin Connector Pin 18 Gauge sending wire.


    4 3 ll 2 1
    9 76


    Sub Tank Harness Wires
    Black Empty ECU
    Red Gauge Switch
    Green Ground

    Relay Coil 85 86
    Coil
    Positive 12 volts on 30 and 87 goes to pump
    Picture.jpg
  3. Romer

    Romer fatherofdaughterofromer Moderator

    Messages:
    9,370
    Location:
    Centennial, Colorado
    excellent, just what I needed on the switch.

    Thanks
  4. cpg

    cpg

    Messages:
    677
    Location:
    Livermore , Ca.
    You are welcome
  5. Romer

    Romer fatherofdaughterofromer Moderator

    Messages:
    9,370
    Location:
    Centennial, Colorado
    Some conversion please. I am using Georges ECU.

    Switch pin4 and pin 3, where do they go? do they just tie together as grounds?

    George's ECU has a SW1 transfer light, does this go to the one marked relay on the switch?
  6. Cruiser804

    Cruiser804 SILVER Star

    Messages:
    1,374
  7. Romer

    Romer fatherofdaughterofromer Moderator

    Messages:
    9,370
    Location:
    Centennial, Colorado
    Perfect. That gave me everything I needed. Kevin does a great job with his write-ups, I used his locker install to put the rear locker in Sarah's truck
  8. Romer

    Romer fatherofdaughterofromer Moderator

    Messages:
    9,370
    Location:
    Centennial, Colorado
    The cab part of the harness is built. One question on where to route something

    Wire 3 from the Sub Tank switch

    Kevin's Diagram has this titled Indicator bulb and does not show where it goes.

    The above info has this titled "Ground and relay 85"​

    What does this hook to?
  9. Cruiser804

    Cruiser804 SILVER Star

    Messages:
    1,374
    The Indicator bulb in the subtank switch gets +12V from the ECU (split wire or whatever), the other side of the bulb (the orange wire that goes no where in Kevin's drawing) connects to body ground or ECU ground (all the same thing). This lets the Indicator bulb light up whenever 12V is sent to the pump - i.e. a transfer is in progress.

    copied from George's instructions to me
  10. Romer

    Romer fatherofdaughterofromer Moderator

    Messages:
    9,370
    Location:
    Centennial, Colorado
    Cool, thanks
  11. Cruiser804

    Cruiser804 SILVER Star

    Messages:
    1,374
    Romer

    Not sure if you have planned to use the factory harness as I mentioned above but I have some additional information.

    I opened up the DS kick panel this weekend and found the plug I referred to in post 7 in this thread: http://forum.ih8mud.com/showthread.php?t=140830&highlight=subtankre

    The 20 pin plug connects to the main chassis harness at the very front (see pic 2), its a little hard to get to. But the 3 pin female cavities are empty (pic 1), the male pins are present in the floor harness. You can see the empty cavities to the left the green wire on the lower right corner of the plug housing.

    So If you want to use this to connect the ECU and gauge to the sending unit it can be done easily. You will need 3 wire repair splices from Dan, PN 82998-12340. These will plug in the housing (pic 1) On the gauge/ecu end you can use a molex (or similar) plug to connect it to the gauge and ecu wires. Since there is a third wire available I am thinking this can be used for the 12v+ for the fuel pump.

    Also, I noticed on the ABS harness mentioned in the above thread that some relocation of the wires in the housings will be necessary. This shouldn't be a big deal since the 2 pin ABS plug and the sending unit plug need to be changed. (provided you do not get the factory harness)

    I have the factory wire harness repair manual that shows how to remove and replace the pins from/in the housing. I am happy to email you the sections you need to perform any of these operations. They also available at toyota techdoc web site for down load.
    Picture 002.jpg Picture 003.jpg

  12. Romer

    Romer fatherofdaughterofromer Moderator

    Messages:
    9,370
    Location:
    Centennial, Colorado
    Thanks for the tip. Can you clarify the below

  13. Cruiser804

    Cruiser804 SILVER Star

    Messages:
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    I also noticed this plug behind the ash tray. It contains a ground, 12v+ constant and a 12v+ ignition. I haven't done my homework on this on but if I can I plan to use this for my 12 volt ignition and ground for the switch. This will reduce the number of splices necessary.

    The housing itself is PN 90980-10997. Dan should be able to get the male housing for this and the repair splices needed to populate the appropriate cavities. Do don't want this PN but the one it mates to.

    The cavity on the left bottom corner is 12+ constant (it had power whether the ignition was on or not), the one next to it is 12v+ignition and the ground is top row forth from the left (brown wiring coming into it.) I checked all these with a multimeter. I did not check to see if one of these was connected to the dimmer for the lights. Didn't think of it until I have everything back together. And I am not really sure what to look for.

    Turns out this is one of three plugs for various radio options. There is also another plug hidden behind the radio. These 2 together have all the speaker connections, a 12v ACC, ground and both sides needed to add another dash light e.g. for the subtank switch. Bummer is, the white/green for the rheostat is in the 6 cavity plug and the green from the 10A dome 12v is in the 10 cavity plug.


    I think I remember a post on the purpose of this plug somewhere. I plan to look for it and post it here.
    Picture 001.jpg
    Last edited: Mar 19, 2007
  14. Romer

    Romer fatherofdaughterofromer Moderator

    Messages:
    9,370
    Location:
    Centennial, Colorado
    You may have missed my post above as it came between yours.

    Another piece of info is that I am not putting my switch where you are as my slots are all filled. I will be putting it over on the left side so I will take the power I need off of the fuse box.

    I could do this by reading the wiring diagram, but have you isolated the existing fuel sender line to splice the switch into?
  15. Cruiser804

    Cruiser804 SILVER Star

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    1,374
  16. Cruiser804

    Cruiser804 SILVER Star

    Messages:
    1,374
    No need to splice to get to the sending unit. I plan to call Dan to discuss and order the parts I need.
  17. is it possible to splice in sections of wire to the ABS harness where the stuff runs along the frame near the wheel?



  18. SWCruiser

    SWCruiser

    Messages:
    561
    Location:
    NY and AZ
    FYI

    I was trying to do the install using the existing harness and ran into some problems. My LX450 does not have the white plug behind the drivers side sill. Also the 3 plugs on the frontmost plug are occupied, WTF. :mad:

    I can tell you that the subtank harness originally connected to the main tank harness and plugged into the white plug behind the drivers sill. The wire gauge for the subtank pump is not as heavy as for the main tank so I believe the gauge of the 3 open wires that go to the DS kickpanel as described is probably sufficient. If my three were open thats the way I would have wired it.

    chris
  19. clownmidget

    clownmidget SILVER Star

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  20. george_tlc

    george_tlc SILVER Star

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