No awd

[Rockridge]

Lol...

Storm dropped 4" today. The drive home was slow and at times quite interesting.

[packmule]

I know this post is over a year old, but I was wondering if you ever figured out the problem? I just purchased a 2004 chevy astro with the only problem being awd not working. I also am not getting a service awd light and the fuse is good. Really don't want to just throw parts at this. 233 swap out of budget as of right now, maybe at a later date. Any info would be extremely helpful. Thank you.

[Popsiclepete]

Very interesting and informative thread here. I am a Newby to astrosafari.com. Just joined yesterday. I’ve been having intermittent problems with the AWD on my 2005 Astro for a couple years and finally decided to fix it. I had a mechanic tell me that I may as well just replace both the transfer case shift motor encoder and the Transfer Case Control Module (TCCM). So, I decided to start with the shift motor encoder which was done a couple days ago and did not fix the problem. I still have no AWD when needed. The fuse is good but I pulled it yesterday after I read on this forum that permanent damage can be done to the transfer case if the codes are not cleared after installing a new shift motor encoder. My first question is what exactly can happen if the codes are not cleared to damage the transfer case? My second question is whether or not replacing the TCCM is the next logical step to fix the AWD? After reading some posts here, I am now wondering if the axel speed sensors might be the problem.

[Mmusicman]

My first question is what exactly can happen if the codes are not cleared to damage the transfer case? My second question is whether or not replacing the TCCM is the next logical step to fix the AWD?

Good questions.
(unfortunately I can't answer)

Is your AWD dash light on?

There's always a chance of numerous failures... TCCM, sensors, connections and wiring.. even internal clutches can be bad. (too many failure-points for me)

If I were going to guess throwing parts at it.. I'd start with the cheapest (or most likely) options first.

Also, are we sure new encoder is installed and working correctly?
To determine.. you "could" actually see if the encoder is getting signal
(wiring to encoder is available in DS kick panel)

When my AWD wasn't "up for the job".. I upgraded it to the manual 4x4 option! lol
(but sticking with AWD is the better option if you drive in snow)

Good luck.. keep us posted

[Popsiclepete]

The Service AWD light comes on intermittently. Seems to have a mind of its own. I’m beginning to like my 98 Astro AWD more and more but it bit the dust (engine) back in 2014. That’s when I bought this 05. Never had a problem with the 98 AWD. Better vehicle all around. I guess I’ll be looking into the 233 conversion or maybe just live with 2WD. Not sure if the new encoder is working. How would I know? Also, what about uncleared codes ruining the transfer case?

[Popsiclepete]

Now I’m going to show my ignorance. DS kick panel?

[Mmusicman]

Now I’m going to show my ignorance. DS kick panel?

Driver side kick panel (wiring harness behind panel left of parking brake)

There are a pair of heavier gauge (guessing 14-16 gauge maybe) black wires that send the signal to the encoder motor (from the TCCM). This would be a possible place to "measure" the signal while attempting to engage the AWD (you would have to pierce or strip back some insulation). Of course the other option (maybe simpler) is to measure the signal at the encoder motor itself directly.

The "signal" is PWM (pulse width modulated).. but should still be readable with test light or VOM.

This is just one option to see if encoder is getting a signal, which would tell you which direction needs possible repair.

Sorry.. still no answer on clearing the TCCM codes.. or if it's even an issue.

[Leeann_93]

I've never had any trouble with the AWD on any of my Astros, including my '05. But I have heard of people having trouble with replacement encoder motors not working out of the box.

So I guess I'd start there with testing, but make sure you put the AWD fuse back in first

[Rod's Trucks]

I believe;
From the diagram Leeann provided, it is obvious there is a 12v signal to operate the motor, but the signal could be a PWM one ( internally done in the module) and a short term one, which reverses the polarity to engage and dis-engage the encoder motor.
If you are going to try to operate the motor on a bench test, with a clip lead, it should only take a few seconds to determine the motor operation.
I would not plan to leave that constant 12v lead applied for more than a few minutes. It probably would not hurt anything, but I would not plan on leaving it connected.
A double-pole and double-throw ( DPDT ) momentary toggle switch with a center off position ( a relatively common switch) could be easily wired to do the task if desired. The momentary designation means you would have to hold your finger on it to keep any current applied to the motor.
You would have to manually switch the encoder ( momentarily )to the disconnect position when no longer needing the AWD function.
Rod J
Issaquah, WA

[Popsiclepete]

Thanks for the input. I’ll let you know what I find out or decide to do.

[packmule]

I believe;
From the diagram Leeann provided, it is obvious there is a 12v signal to operate the motor, but the signal could be a PWM one ( internally done in the module) and a short term one, which reverses the polarity to engage and dis-engage the encoder motor.
If you are going to try to operate the motor on a bench test, with a clip lead, it should only take a few seconds to determine the motor operation.
I would not plan to leave that constant 12v lead applied for more than a few minutes. It probably would not hurt anything, but I would not plan on leaving it connected.
A double-pole and double-throw ( DPDT ) momentary toggle switch with a center off position ( a relatively common switch) could be easily wired to do the task if desired. The momentary designation means you would have to hold your finger on it to keep any current applied to the motor.
You would have to manually switch the encoder ( momentarily )to the disconnect position when no longer needing the AWD function.
Rod J
Issaquah, WA

Could you wire a three way switch to engage AWD? Such as: up, then back to center, to turn on, down and back to center to turn off?

[AstroWill]

The Service AWD light comes on intermittently.

What codes are stored?

[Rockridge]

Wow, a year later and I'm still driving around with just 2wd. Too many projects and too little time! A great set of snow tires has helped me tackle the driveway most days this winter. Of we get alot of snow I just leave it at the bottom and hike.

I will be tackling the transfer case swap soon and will provide photos of my solution. Have a friend with a lift and talent so should be a good time.

Planning on opening up the awd transfer case to see whats up, if anything. Looking forward to 4 low for pulling the boat up the ramp, possibly plowing and whatever.