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Boxer54, Toyota Technician
Category: Toyota
Satisfied Customers: 1753
Experience:  ASE Master tech with L1 certification, Toyota Master Diagnostic Technician
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toyota: 4x4 light flashing on 2000 4 runner

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4x4 light flashing on 2000 4 runner
Thank you for trusting us with your Toyota question. Did this just suddenly start on its own, or is there anything that led up to it?
Customer: replied 3 years ago.

been acting up for the customer. im a shop. 4x4 lights flashed all the time no matter what position. put in the 3 switches on the t case. now the wheel indicators are green in 2x , supposed to be off and when switched to any 4x position thy flash

Remove the detent switch on the front differential and check it with an ohm meter. If that switch fails, you will get these symptoms.
Customer: replied 3 years ago.

youre talking the poppet switch on the front axle vac. motor correct?

Should be the only switch on the front axle.
Customer: replied 3 years ago.

switch retests fine. no matter where the lever or button is the vac is always applied to the pull side of the actuator

That makes me think even more that switch is likely the culprit. Run me through how you tested the switch. With it removed, you should have an open circuit that closes when the switch is depressed. Is this the result you got?
Customer: replied 3 years ago.


Are you familiar with how to backprobe a connector?
Customer: replied 3 years ago.


The 4 wd ecu is located behind the kick panel on the drivers side. Get to it and I will get the pinout locations for all the switches so we can check them at the computer. Give me a bit to put it together.
Customer: replied 3 years ago.


Which engine is in your 4 runner, the diagrams are slightly different.
Customer: replied 3 years ago.


Here's a link to download the connector view

I'm going to list the switch locations and what you should see when backprobed with everything in 2wd
Pin 19 ADD switch open in 2Wd
Pin 5 4wd detection switch open in 2wd
Pin 18 H4/L switch open in 2wd
Pin 7 center diff lock open in 2wd
Pin 4 2-4 select switch open in 2wd

Check those to see if any show a ground with everything in 2wd position.
Customer: replied 3 years ago.

thanks. link defective. will see if I can see #'s

Customer: replied 3 years ago.

thanks. link defective. will see if I can see #'s no #'s. can you get me 2 or 3 wire colors. I can orientate from there

That's odd. I just copied the link into a separate browser and it went straight to the download. Pin 19 is black with blue tracer and pin 5 is red with black tracer.
Customer: replied 3 years ago.

got link finally. my red / blk is pin 6 12v

4 pink 244 ohms

7 grey 12v

18 br/yl 12v

19 bk/bl gd

Can you clarify pin 19 and pin 4. If checking voltage it should be 0 volts or 12 volts.
Customer: replied 3 years ago.
>key on lever in 2wd. 0 v on both 19 and 4
Make sure the 2-4 select button is out, that is pin 4 and should not be grounded. The other is the ADD detection switch and should not be grounded in 2 wheel. Make sure the front wheels are not locked to the driveline.
Customer: replied 3 years ago.

front wheels are locked wont switch unless I swap vac lines side to side. pin 4 picks up voltage switch applied

Remove the pin from the connector at pin 4, leave vacuum lines off at vacuum valves, then try it and see if the lights stay off and it stays in 2wd.
Customer: replied 3 years ago.

made it worse. instead of the green wheel indicator lights on now everything flashes like when you would put it in 4x4

I see why. Use a vacuum pump and unlock the front differential.
Customer: replied 3 years ago.


Is the transfer case in 2 wheel orXXXXX check to see if the front driveline is locked together with the rear. Ill do some more research about that switch. The diagram shows it open in 2 wd position, but I will dig a little deeper.
Customer: replied 3 years ago.

they are locked together, I thought they were out, must have missed that

Customer: replied 3 years ago.

transfer case works manually in n and 4l. case is always locked except in n. front axle always locked. is the computer the only thing that commands the auto lock. I had previously pulled off the auto motor and tested it but couldn't test the commands to it

Did you disassemble the transfer case to remove the actuator?
Customer: replied 3 years ago.

no pulled the cover off the side of the actuator, pulled out the drive gear . bench tested the motor and re assembled. worked the same after as before. about ready to just get a computer and t case.

Those actuators are a BIG pain once you do this. Proper installation is done by disassembling the case. Here's what to do. Take it off and manually shift the case to 2wd. On the bench run the motor all the way counterclockwise (pulling the shaft out), then just tap the contacts to move it back just a little. Now the trick is to put it back on without pushing the shaft in and going back into 4 wd. Once done, make sure the ADD on the front diff is unlocked and try it again. If its still not right, your best option may be a complete, used case with the actuator attached.
Customer: replied 3 years ago.

did the retime, didn't work. ordered a t case thanks

Let me know if you run into any more trouble with this.
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