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I'm not so sure there is a logic module down there. Thinking it is just a microswitch perhaps. Anyway, the signal back to the TCCM on a blk/wht wire to pin B6 of Connector 2 of the TCCM is battery voltage when front axles locked and essentially zero (maybe 20 mV) when front axles unlocked.
 

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The main question is what is the HIGH voltage of the control signal from the TCCM (lt blu wire on pin C1/A2 of the TCCM)?
Just backprobed that one at the TCCM like I did the blk/wht. A little less accessible than the blk/wht but not real difficult. Same voltages seen but in reverse order. Battery voltage unlocked, up to 90mV locked.
 

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Not sure if this has any bearing on your plans but I tested something else and determined the battery voltage on the blk/wht appears to be sourced from the 4WD fuse in the rear fuseblock. I concluded this by removing the 4WD fuse while in A4WD. The backprobed voltage on the blk/wht went away and the mode switch changed from solid A4WD to A4WD flashing and a solid light at 2Hi. Without the 12 volt on the blk/wht I guess the TCCM reverted to a state of attempting a shift from 2Hi to A4WD??

Also, when the TCCM determines a successful shift has been made a message is sent in the class 2 data bus to the functional address 3B and is acknowledged by the PCM and the EBCM. I won't claim to have even the slightest idea of the purpose of this messaging.
 

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I have wiring diagrams but they only show the actuator as a simple block with no internals detailed.

What I was observing was that from the perspective of a driver, if the 4wd fuse were to fail, the mode switch will display identical conditions (lighting) to an attempted shift in progress from 2Hi to A4WD.

Incorporating a delay seems logical. Do you know if the TCCM calibration differs in the AWD models of the TCCM?
 

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OK, an update - I created a circuit that receives the 12V signal and inverts it after a delay. However, I am somewhat confused. In the first post here it is written that "the control signal from the TCCM goes high to command the actuator to extend its probe for 4WD, and goes low to command retraction for 2WD. There is a feedback signal that confirms to the TCCM that the actuator is working, and it sends a low for extended and a high for retracted". My circuit is working similarly. However, I just realized that Mr. TJBaker described the reverse situation: the control signal is "battery voltage unlocked, up to 90mV locked " and "the signal back to the TCCM ... is battery voltage when front axles locked and essentially zero (maybe 20 mV) when front axles unlocked". Which situation is correct?
Indeed I noted the same discrepancy and that was one reason why I worded my post using 'battery voltage' to be clear of my observations.

I will double check this evening but I am fairly certain my post on the state of voltages is what I observed.
 

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So I am now certain as I can be of my measurements. The only edit would be that the high voltage is not quite 'battery voltage' but some output of slightly lesser potential from the TCCM or actuator. Here are some pics of my latest backprobing of the blk/wht signal wire from actuator to TCCM C2,B6

42mVDC in 2Hi, unlocked axles

11.51 VDC in A4WD, locked axles

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I was noodling around with one a few months ago. There is a 12 volts source, a ground, a control signal and an output signal. The output signal is not needed to operate the actuator but is used to report the status. Grounding the control wire activates the unit...

 

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Another quick question; What rough diameter are the axle shafts themselves (not the splines) and are both sides of the 4x4 actuator the same axle splines or are they different
I am away from home until Saturday. I can chexk when I return.
 

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Not sure about any "switch" in the actuator that could click. There is a slider attached to the mechanism that is the only switching going on in there. Double check your connections/terminals??

Here is a look inside...

 

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how long is the stroke on that thing anyway?

Here it is fully extended. Note the coil spring inside the "pusher" cylinder. If something is misaligned or otherwise stuck in the gears and fork assembly the coil spring allows for the actuator motor and related circuitry to still travel the full extent but not engage the disconnect. If the gears then move slightly to a properly aligned state the coil spring will then extend and move the shift fork etc to engage the gearing. When I disassembled my disconnect in 2014 I found a thrust washer that is supposed to be between the two gears had worn and slipped down to a position that blocked the travel of the shift fork and collar gear. My actuator still travelled the full distance and sent the signal back to the TCCM indicating it was engaged but in fact only the coil spring was compressed and the gearing was inhibited by the misplaced thrust washer.

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when I ground the blue wire the actuator pushes out like it should, sounds like its under load (its not jamming the gears, they're engaged correctly) then slows to a stop. if I keep the blue wire grounded the actuator gets quite warm

What is the status of the feedback signal wire at this point? Would it indicate full engagement to the TCCM if you were using one?
 

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The actuator would be out all the way. It just didnt seem to stop trying to move. it was under load and got hot so I disconnected it and now it wont do anything.
Here is a look inside. There is a slider/jumper that travels with the actuator, making contacts across several strips on the circuit board. Wonder if something got fried there...

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