2005 Silverado 4X4 problem

[lawdog]

Any idea what to expect when I bring my truck in after I got a "service 4wd" message and the thing wouldn't go into 4wd for me as I was dang near stuck down by the creek in the pasture last week??? Its got the auto 4wd and the regular on an electronic switch.

[Jeremy airjer W]

You'll have to see what codes are stored but if it didn't go into 4wd i would have to wonder if the encoder motor, shaft, t-case is bad. Have you ever had the transfer case serviced?

[lawdog]

Not that I recall. I do whatever they recommend on the intervals though so if was due for service it got it.

[KatoMike]

Every Chevy 4x4 I have had in the last 10 years (4 of them; some of the trucks did this several times) gave me this message - each time it was the actuator. Very common problem with Chevy 4x4s.

I now have a Super Duty with manual locking hubs and manual 4x4 lever - no more actuator issues.

[Macgyver55]

Every Chevy 4x4 I have had in the last 10 years (4 of them; some of the trucks did this several times) gave me this message - each time it was the actuator. Very common problem with Chevy 4x4s.

[KatoMike]

The actuator issue isn't why I went from Chevy to Ford, I have really liked all the Chevy trucks I have had and the issue was fixed under warranty on all the trucks.

[LMITOUT]

Bad 4x4 selector switch perhaps? Common problem.

If you know someone with a similar truck you might sweet talk them into letting them try their switch. It's a 5 min job to pop it out.

Pop the dash bezel off that surrounds the instrument cluster, radio, etc. I like to start at the corner above the radio. Usually can just grab with the tips of your fingers and give a gentle pull to start popping out the retainers. Tilt the steering wheel all the way down into your lap and keep working your way around the bezel. After releasing all the retainers you'll have to angle it towards you and wiggle it a bit to free it from the rubber seal on top of the steering console. Take your time and it'll come out with some maneuvering.

After you put that aside you'll see that the 4x4 selector switch "cube" is accessible. Shine a flashlight between the cracks around the cube and you'll see some retainers. Slide a flat screwdriver or butter knife for that matter to release the clips. It should pull out and then you can unhook the wiring harness. Reverse the process to complete the change out.

[LMITOUT]

I also found this service bulletin:

Quote:

Condition

Some customers may comment on intermittent illumination of the "Service 4WD" light. Upon investigation, the technician may find DTC C0374 set. The customer may also comment on intermittent erratic operation of the 4WD or AWD system after driving through rain/snow or simply going through a car wash.

Cause

The speed sensor signal may have become corrupted. Possible openings in the speed sensor wire insulation (twisted pairs) can allow water intrusion. Also, wire connections contaminated by water may result in short circuits and erroneous speed sensor readings. This most often occurs on the rear speed sensor circuit.

Correction

Inspect the wiring harness to the transfer case speed sensors. On Rainier, TrailBlazer, Envoy and 9-7X models, fabricate a replacement speed sensor harness between the C101 connector and the speed sensors. Refer to Speed Signal, Front Axle Actuator, and Indicators schematic in SI. Replace the affected twisted pairs. Do not over-twist the two wires in the replacement harness. Use service connector pack, P/N 88987183, at the speed sensor end and terminal, P/N 15326267, at C101.

On the full-size pickup and full-size utility models, replace the 2.2 m (88 in) pigtail harness that runs from the C151 connector under the hood to the transfer case. Use either harness, P/N 15224661 or 15224663, depending on vehicle equipment. Refer to Propshaft Speed Sensors, Front Axle Actuator and Transfer Case Shift Control Switch schematic in SI.

[aczr2k]

I'd bet money on the switch, it is VERY common.

[Scott K]

I'd bet money on the switch, it is VERY common.

So are the actuators, shift motors, and 4x4 modules.

Switches are the easiest to pull and test. Although, I would start with pulling codes, or testing the switch.

[lawdog]

We'll find out this afternoon it goes to the shop after lunch...

[lawdog]

And the Winner is...Actuator.

And the loser is me! $200.70 worth!!!