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4wd Actuator

Big T

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Did some electrical tests on the 4wd actuator in the front differential of the '99 and the actuator is not functioning. It is stuck in the 4wd position, yet I only get blinking lights on the switch at the dash. I changed that switch and no difference. I tested down at the plug and it is getting power down there. I can also hear the encoder motor working in in the transfer case.

So I ordered a new 4wd actuator. Initially ordered a Niyako Chinesium unit for $39 off Amazon, but tracking showed it had not yet shipped and I ordered it on Monday. So I cancelled that order and went on Rockauto. GM Genuine $122 with 24-month warranty, or Standard Motor Parts $84 with 36-month warranty. Not seeing much difference in the parts and I'm sure they're all made in China now, so I went with the Standard Motor Parts unit.
 

dbrannon79

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Does those actuators have plastic gears in them like the mode and temp actuators in the dash? there might be a repair kit available for them
 

RI Chevy Silveradoman

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Fuggin Spammers!!! 🤬

I have this same issue on my 2006 Duramax. Replaced front actuator, Tcase encoder motor, and switch. Checked grounds under drivers seat first. Still no 4wd. I tested switch. I was getting the 5v check. Just basically giving up.
 

Big T

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Fuggin Spammers!!! 🤬

I have this same issue on my 2006 Duramax. Replaced front actuator, Tcase encoder motor, and switch. Checked grounds under drivers seat first. Still no 4wd. I tested switch. I was getting the 5v check. Just basically giving up.
Can't give up as I need 4wd.

Lost 4Lo years ago and could never figure out the issue. When I replaced the transmission I also replaced the original transfer case to avoid the pump rub issue. New reman transfer case has an alumimum rear case vs the OEM Magnesium. Provided transmission, transfer case and new AC Delco Encoder Motor to my local Montana Mechanic to install. He said he could not get the AC Delco encoder motor to work (returned for refund), so he reinstalled the original which left me with just 2Hi, 4Hi, AWD. Then early this fall I lost 4Hi and AWD. Replaced the dash switch, nope. Just replaced the actuator as the old one was verified not working. New one verified as working. I can hear the Encoder Motor moving, but no 4wd. I have another new Encoder Motor from a canceled transfer case order, so my next step is to install that.

I do like the potential of the NP 246 transfer case as the AWD function is great on snow and ice. The reliability of the electronics on it has sucked.
 

Big T

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I gave up on getting the ABS braking to work. Previous Owner had it unplugged. I plugged it back in and it worked intermittently before going out. I tried a replacement ABS unit from an wrecking yard with no change. The ABS light is mostly on, though intermittently will be off for a short while after start-up. Then two weeks ago I was going slowly downhill on an icy dirt road and suddenly felt and heard the ABS work for a second or two. Obviously this is electrical and I’m wondering if it’s related to the encoder motor. I thought the rear wheel ABS is controlled by a sensor on the transfer case?
 
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dbrannon79

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Just curious on your rig, would there be a separate body control module from the ECM that controls parts or all of the 4x4 function? something that only a tech 2 or specialized scanner would be able to read codes and data from seeing if there is something preventing the 4x4 from working?
 

Big T

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Just curious on your rig, would there be a separate body control module from the ECM that controls parts or all of the 4x4 function? something that only a tech 2 or specialized scanner would be able to read codes and data from seeing if there is something preventing the 4x4 from working?
Yes it called the Transfer Case Control Module and it’s located under the dash between steering column and the body. I replaced this and the reman part was $140. No change. Doubt the original one was having issues.

I have the replacement encoder motor after canceling my transfer case rebuilder with a shop in Portland, OR. They would not refund the cost of the encoder motor, so I instructed them to ship it to me. It’s a Dorman part. Not ideal, but I’ve got it. I have had success with other Dorman parts. Like the old 4WD actuator was a Dorman part and it went 12 years.
 

Will L.

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I do have the CKO Tech II. I will plug that in and see what codes I can find……when it warms up over the weekend. Currently it is 1 F with howling wind and going down to -16 F tonight.
I was referring to a push/pull cable to eliminate the electrical controls.
Hilariously I am back to playing electrician for my nickels- but prefer mechanical items over electrical. Could be I have seen to many overly complicated electrical things (ds4) when a mechanical one does a better job (db2).
I wish I could remember the name of the cable system to use here but I forgot the name.
 
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