2005 Tahoe 4WD Question

[Bob Mac]

I have removed the 2 4WD Fuses, 1 - in engine compartment & 1 - inside cab, will this stop the 4WD from randomly selecting 4Lo? I need to be able to drive the Tahoe until I can get it fixed. I do not want to end up being a blocking disabled on I5.

 

[2591tdj]

I have removed the 2 4WD Fuses, 1 - in engine compartment & 1 - inside cab, will this stop the 4WD from randomly selecting 4Lo? I need to be able to drive the Tahoe until I can get it fixed. I do not want to end up being a blocking disabled on I5.

Did you ever solve your 4Wd low problem? If not, you may want to read some of the postings under Service 4WD light. Mine would randomly go from 2wd into 4 Low. I can’t remember the part name but it was a small circular sensor located on the Tcase almost under the driver’s seat.

 

[rockola1971]

Was the Tcase actually go into 4Lo or was the indicator on the dash showing it was in 4Lo even though it was actually in 4Hi. These are 2 very different problems.

 

[2591tdj]

Was the Tcase actually go into 4Lo or was the indicator on the dash showing it was in 4Lo even though it was actually in 4Hi. These are 2 very different problems.

It downshifted into 4 Low in a parking lot. I don’t recall even noticing what the indicator showed. And, it didn’t want to shift back out of 4 low. I kept shifting from forward to reverse until it made a loud pop and finally shifted back into 2wd.

 

[rockola1971]

It downshifted into 4 Low in a parking lot. I don’t recall even noticing what the indicator showed. And, it didn’t want to shift back out of 4 low. I kept shifting from forward to reverse until it made a loud pop and finally shifted back into 2wd.

You have to be in neutral and not moving to shift to or from 4low !

 

[2591tdj]

Yep. You are absolutely correct. It was bizarre. I was stopped in a parking lot because it would barely move and was making a racket. I thought the transfer case was coming apart. Another time when I started it in my driveway it was already in 4 low and did show such on the switch. I had never used 4L or even shifted into 4L before. I found that it only acted up and the Service 4Wd message only came on the DIC on cold, icy mornings or when I had driven in the rain. That was a clue to me that something electrical was getting wet and shorting out.

 

[rockola1971]

Id get that fixed. Cant imagine how much your butt would have to pucker going 55mph+ down a highway and the vehicle get a mind of its own and shift itself into 4lo ! Holy cow that would not be pretty! Id be afraid the Tcase chain would end up burried in the floorboard.

 

[2591tdj]

I did fix it. It was essentially not drivable. This little part was apparently shorting out and causing the problem.

 

[TJ Baker]

I did fix it. It was essentially not drivable.View attachment 233998 This little part was apparently shorting out and causing the problem.

If you were to closely inspect one of these encoder rings it can be seen that over time the little wipers that are intended to return a voltage signal to the TCM can both wear into the resistive material and also build up a load of debris on the wiper itself resulting in a fluctuating voltage return signal.