joe0072

I have a 03 Silverado that has been having 4 wheel problems for a year.I got in and started truck up one day and backed out and noticed 4 lo light was on, I stopped and put in neutral and pushed 2 hi and it shifted and all good,for a couple months.Then on start up it would be in 4 lo or 4 hi or auto and again I stop go to neutral push 2 hi and all good for a week or 2.And sometimes the red light comes on then I shut the truck off and restart and all is good, this has only happened 2 times in 6 months. Also 3 times the service 4 wheel drive warning came on, first time checked everything fluids ,electrical connections etc,I always stop go to neutral shut truck off restart red light or service 4 wheel drive is gone and all is good.Haven't had any problems for 6 weeks this mourning started up and was in 4 lo did the neutral trick and good to go.I don't just want to start throwing parts at it. I use 4 wheel drive a lot picking up hay pulling a trailer and hope some of you guys can help end this problem.
Thanks Joe C

burhead1

Looking at you name i am going to guess your 42 year old Joe

If possible you may want to first have it scanned for codes, the codes can help in diagnosing your problem.

A few things you can have a look at are the encoder motor (the motor attached to the transfer case). They are bad for corrosion on the backside of the motor, the side facing the transfer case. The corrosion can be so bad it may be split open. Also check the connections at the Transfer Case Shift Control Module.

joe0072

I had a guy scan it and he said it had no faults but he went in to the history and it had a code C0327. I looked at all the possibilities from the push button switch to the encoder sensor, motor connections ,to loose grounds. I have checked all the connections that I can without pulling the servo motor. And I ruled out the 4 wheel push button switch from what I read online because the red neutral light on the 4 wheel push button isn't on and the wheel drive works great. Am I over looking any thing? I would appreciate any advice or help.
Thanks Joe C

burhead1

DTC C0327

Circuit Description

The transfer case encoder is an analog sensor that returns a signal that represents the physical position of the transfer case sector shaft. This signal represents the mode or position that the transfer case is currently in. This sensor is made up of the following 3 circuits:

A 5-volt reference circuit.
An encoder signal circuit.
An encoder low reference circuit.
This DTC detects an out of range reading from the encoder signal, a short to voltage on the 5-volt reference circuit.

Conditions for Setting the DTC

The transfer case shift control module has a predefined range, 0.5-4.5 volts, in which the encoder feed back should stay within. The DTC sets if the encoder signal feed back falls out of this range.

Action Taken When the DTC Sets

All motor activity stops and the transfer case lock engages.
The SERVICE 4WD indicator remains illuminated for the remainder of the current ignition cycle.
Conditions for Clearing the DTC

The transfer case shift control module will clear the DTC if the condition for setting the DTC is not currently present.
A history DTC will clear after 100 consecutive ignition cycles without a fault present.
History DTCs can be cleared using a scan tool.
Diagnostic Aids

Check the mechanical condition of the shift lever detent shaft connected to the motor. If this shaft has too much mechanical play this can cause an under voltage or over voltage from the encoder causing the DTC to set.

Shaft may be binding on cold days? hard to find when it is so intermittent.

joe0072

I've been trying to find something else wrong causing the problem, but I think its time to take out the motor assembly and have a look. The only thing is that the service 4 wheel light has just come on 3 times in 1 year, and hasn't came on in 6 months. To cold right now in the pole barn. Thanks a lot for helping Joe C