4WD Switch?

[mattt]

My 04 Tahoe has started up with this problem. Sometimes, the 4x switch shows 2HI as it should, other times it shows in neutral ( red light ) and runs like a dog, and other times it shows 4 LOW and runs like a beaten injured dog. When in 4 LOW the shifting of the transmission is so screwed up, but I've learned how to deal with driving it when it's stuck in that mode.

I do not believe it is going into 4wd at all. I see the problem could be the dash switch assy, or it could be the encoder motor position sensor.

My question.....how can I tell which of those two is causing the problem?

 

[destroyer1362]

My 04 Tahoe has started up with this problem. Sometimes, the 4x switch shows 2HI as it should, other times it shows in neutral ( red light ) and runs like a dog, and other times it shows 4 LOW and runs like a beaten injured dog. When in 4 LOW the shifting of the transmission is so screwed up, but I've learned how to deal with driving it when it's stuck in that mode.

I do not believe it is going into 4wd at all. I see the problem could be the dash switch assy, or it could be the encoder motor position sensor.

My question.....how can I tell which of those two is causing the problem?

You could grab a scan tool, I have a Autophix OM123, its cheap ($35) and it works. It will be able to show you what the encoder is seeing 4wd/2wd/hi/lo etc.. If you press 4hi, and the encoder info shows 4hi then you can rule that part out..

 

[mattt]

I have an Actron CP9145 OBD2, OBD1 code reader. Would you happen to know if this has the ability to read the encoders output?

 

[destroyer1362]

I have an Actron CP9145 OBD2, OBD1 code reader. Would you happen to know if this has the ability to read the encoders output?

I don't believe so, it looks like you can read some data but not 4x4 info..

Heres a vid to the data you should see if you can view 4x4 data. Skip to around 7:20

 

[speedmachine]

It's not the switch.

It's 99% the encoder motor position sensor.

Yep, I had the same problem along with "SERVICE 4WD" message on the dash. This was the cause, took about 2 hours to change. $50 or so for the part from Rockauto.

 

[ATIII]

Mine was doing the same things. Changed the switch and it seemed to correct it temporarily. End of story is the encoder motor was jacked and $1100.00 and a winter under its belt it's fixed.


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[SLCHOE]

Mine was doing the same things. Changed the switch and it seemed to correct it temporarily. End of story is the encoder motor was jacked and $1100.00 and a winter under its belt it's fixed.


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The encoder motor position sensor is a $40 part inside of the $500+ encoder motor. The motor itself either works or it doesn't in the majority of cases. The $40 sensor is what is the problem 9 times out of 10.

Pull the encoder motor down and open it up. Replace the sensor and save yourself $1060 next time. Literally a 60 minute job on your back in the driveway. I can do them on the lift in 25 minutes.

 

[ATIII]

The encoder motor position sensor is a $40 part inside of the $500+ encoder motor. The motor itself either works or it doesn't in the majority of cases. The $40 sensor is what is the problem. Pull the encoder motor down and open it up. Replace the sensor and save yourself $1060 next time.

It ended up being more damage inside the T Case as well. Bent Forks I believe.


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[SLCHOE]

Fork?

 

[SLCHOE]

ATIII who makes those nerf bars/steps on your rig? I like them.