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I have a 2006 2AZ-FE with 4WD (ASA33L-ANPXKS). I'm checking for a bad wheel bearing or half-shaft and raised a front wheel off the ground (the wheel removed) so I can spin that hub without the car being able to move. To my surprise, both rear wheels are getting drive power even though the 4WD indicator was unlit/off. Does this mean the 4WD engagement is stuck engaged?

Is rear drive activated by an electric clutch ? If so, can I prevent 4WD by 'pulling the plug' ?

TIA
 

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The 4WD light is for errors only. It indicates the rear drive isn't working not that it is. If you're trying to spin the front hub with the engine the rear drive will be activated since it always is at takeoff. Disconnecting the plug at the 4WD ECM behind the glove box will disable it.
 
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Discussion Starter #3
No, the 4WD error light was -not- on. It seems that the vehicle is always in 4 wheel drive -mode ! When driving in 1st or 2nd gear pushing the 4WD mode button lights the 4-wheel-drive mode indicator, but I can't actually hear or feel anything to indicate that the rear drive is engaging. Going into 3rd gear turns off the rear drive indicator, but again, I can't hear or feel anything that suggests the rear driveline is disengaging. I'm thinking the rear wheels are always stuck in drive mode. Can this happen ? Is the engagement mechanism an electric clutch (like an A/C pulley clutch) or is there some kind of gear in the transmission that is engaged by a solenoid ?

"... the rear drive will be activated since it always is at takeoff." Really ?! When is it supposed to disengage ? Going into 2nd gear ? When put into 4WD mode it automatically disengages when going up into 3rd gear, that is, the rear drive mode indicator light goes out and stays off. How is this system supposed to work ?
 

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We've had many discussions on the operation of the 4.3's 4WD system and someone may provide links for your reading pleasure. But let me give you the basics.

The rear drive is activated by a variable electro-coupler mounted on the front of the rear differential. It's controlled by the 4WD ECM based on inputs from various sensors, several accelerometers and wheel speed sensors among them. Operation of the system is transparent to the driver, engagement and disengagement being imperceptible. Their are no clunks of solenoids or gears as on my F250 when I select 4X4 or 4X4-LO on the dash.

In fact the only way I know when the rear drive is active on our RAV4 is via a green LED I mounted on the dash and wired to the coupler drive signal. It comes on ASA I shift into any gear forward or reverse. Unless I'm V6-accelerating hard it fades off by 10-15 mph. On a slippery surface under a heavy right foot I might could keep it on another 10-15 mph.

Releasing the gas shuts it off instantly. That's effectively the only thing the 4WD Lock button does different. It holds the rear drive ON up to 25 mph regardless of acceleration or deceleration. Most members find it of little use.
 

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I don't want to hijack this thread, but I wonder if Dr Dyno posted instructions for the green LED which indicates that AWD is engaged?
If so...
TIA.
 

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No he didn't. It's not easy to do.
 

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But you're not a guy who is afraid of "not easy".
Give us a clue, please?
 

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