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Skyvisions, ASE Certified Technician
Category: Toyota
Satisfied Customers: 14324
Experience:  Toyota Master Diagnostic
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Tacoma 4x4: I have a 2003 Toyota Tacoma 4x4. When i engage

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I have a 2003 Toyota Tacoma 4x4. When i engage the 4WD system, normally i see the green 4WD light illuminates. Now when I engage the 4WD system, it only engages and the light does not illuminate. I have pulled out the cluster and checked the bulb and yes it is good. Need your help
Thank you for choosing JustAnswer and allowing me to help you resolve your Toyota questions! Are you 100% certain that the vehicle is in fact in four-wheel drive?
Customer: replied 3 years ago.

what kind of info

have you confirmed that it is definitely in four-wheel drive?
Customer: replied 3 years ago.

yes i have, u can feel the change when u start moving

Let me look into the wiring diagram and I'll see where the switch is that controls the power to that light. I will get back to you within the hour.
Customer: replied 3 years ago.

thank you



There is a detection switch for 4 WD on the left side of the transfer case there is a two wire connector going to it. The black wire with a yellow tracer and a white wire with a black tracer. If you disconnect the switch and place a jumper wire across the two female pins does the four-wheel drive light illuminate? It does then the switch is bad. If it does not then it requires extensive diagnostic testing of the automatic disconnecting differential mechanism and switch that is Incorporated into the unit. Typically though when this fails it will not shifting the four-wheel drive.

Customer: replied 3 years ago.

i am under the vehicle now and not seeing it. tell me where to look

Click the link below to enlarge.



Customer: replied 3 years ago.

base on the diagram I am seeing it looks like an engine bay overview. the only two pin connector i am seeing looks like a cam/crank angle sensor.

This is a shot of the engine bay but that harness that goes beyond and down underneath is how they show up for the connectors that go to the transmission.
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Customer: replied 3 years ago.

saw the only 2 pin connector, removed it and tried to clean it up with parts cleaner. as i said it looks like a crank sensor with a metal point protruding.

loop the pin into the female connector and still no light.

Customer: replied 3 years ago.

Look at T3


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T3 is a two – four select switch. You should not have this feature if you have the manual shift to manually shift the four-wheel-drive.
Customer: replied 3 years ago.

ok. not sure what else to do. any other suggestion..

Without getting into sensor diagnostics of the ADD actuator and the wiring harness provided it still shifting into four-wheel drive I would not be too concerned about the indicator light on the instrument panel. The bottom line is you know it's in four-wheel drive then you know when to take it out.
Customer: replied 3 years ago.

My sentiments exactly. You have been great help. Whenever u come to the Caribbean u can give me a call. I went underneath the vehicle and looked at the front prop shaft when the 4WD is engaged and i can see it twist and turn when u put the selector lever into either R or D.


When the 4WD drive is disengaged and put the selector lever into R or D, on the rear prop shaft twist.


So with all that being said and done, i am fully convinced that the 4WD is working.

You are welcome. Have a great weekend and I would love to get down there sometime have never been.
Customer: replied 3 years ago.

have a great one too.




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