Stuck in 4WD

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wsteele

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That's exactly what that is, the range position sensor. Maybe it's the brains and the motor is the brawn. In the older TCs they're integrated.
That is what I was thinking. The TCCM knows exactly what position it has the TC in as the sensor is keyed. Likely you just pop the motor in and the TCCM displays whatever position the TC is in on the switch. You change the position selection and the TCCM tells the motor how many steps to go right or left and has the sensor to know when it got there.

Still wonder why the need for motor learn in that last bit of the shop manual that James displayed above. The guys making the video don't mention anything about starting in a particular position (like neutral) and no motor learn at the end...
 

wsteele

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After all this, I sure hope it turns out to be the motor and not just the sensor, or the TCCM or chafed wires from the harness coming loose and rubbing on the front axle drive shaft. I guess all that preliminary debug does make sense... ;)
 

Fless

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Who knows, maybe some or all of the tests will get done when the motor is replaced. If I was going under there, I'd be curious and would do the tests before changing the motor out. It's just a couple of readings with a DVOM.
 

wsteele

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Who knows, maybe some or all of the tests will get done when the motor is replaced. If I was going under there, I'd be curious and would do the tests before changing the motor out. It's just a couple of readings with a DVOM.
You know, thinking about it, I wonder if the shop manual fragments James posted are for the right year? With the setup in the video, the resistance range test would be on the sensor and if not within that rheostats proper range, it would call out replacing the sensor, not the actuator (motor).

Also, I think the OP better check RPO's before buying anything.
 

Fless

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You know, thinking about it, I wonder if the shop manual fragments James posted are for the right year? With the setup in the video, the resistance range test would be on the sensor and if not within that rheostats proper range, it would call out replacing the sensor, not the actuator (motor).

Also, I think the OP better check RPO's before buying anything.

Except that the component test is on the motor/actuator lock circuit, not the range selection. The lock circuit keeps the motor from moving when not changing modes.
 

wsteele

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Except that the component test is on the motor/actuator lock circuit, not the range selection. The lock circuit keeps the motor from moving when not changing modes.
So basically, with this fault code, it is just checking that the coil in the lock solenoid is OK. If the lock solenoid is not bad, then it has to be the TCCM at that point.

I definitely would be doing the multimeter checks called out in James post before buying parts, especially with the revelation of the separate sensor and motor.
 

wsteele

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I went out and doubled checked and I do have the old style (RPO NP8) on my 2007 Yukon (but also have the rotary switch, like the NQH), so have the old style TC Motor with the integrated position sensor ring. The new style with the separate sensor and motor assembly (RPO NQH) I guess actually started in 2008, at least in Yukons.
 
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