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"service awd" light. Problem solved!

50K views 28 replies 18 participants last post by  AstroWill 
#1 ·
I thought I would share the solution to my problem since I have read other threads with similar issues. I just bought this 2005 AWD Astro Cargo Van for my business. I live in Iowa so the AWD is great! It has 170,000 miles on it, but they are highway miles from the previous leasee. From the start I noticed a kind of slight "grabby" feeling as I would accelerate from a stop on dry pavement going in a straight line. After reading threads about the Auto TrakII synthetic lube, I had the transfer case fluid changed. The mechanic said I already had the Auto trakII in the transfer case, but it was old and broken down. That fixed the problem with the "grabby" issue immediately! My main issue however has been that the "service awd" light would come on and off, and when the light was on, I had no awd. It would happen like this. When I go to start the van, most of the time I would hear a clicking noise in the kick panel by my left foot. About 4-5 clicks. Then the light comes on and stays on. Then, I get to my next job site, turn the van off, start it back up an hour later and no clicking sound or "awd light". More than half the time the light comes on though. I figured it could be the encoder motor, but didn't want to spend $581.00 on a hunch, "dealer price". So I found out I could get a non-OEM encoder motor at Oreilly's for 145.00 + 25.00 core, lifetime warranty. I just installed it today and it works PERFECT! I know this because we just got 6 inches of snow. I am curious to see how long this encoder motor lasts though. Thanks Astrosafari.com!
 
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#3 ·
That's a great write-up rubrbulits, thanks for posting it.

I'm sure this will definitely help others in the same situation that you had.:)
 
#4 ·
Yup, that's the problem with these electronically controlled drivetrains...the average guy can't just dive into them and figure out what the problem is without a proper scanner. I was just quoted $275 to have my van thrown on the computer and have the PCM and transmission gone over to have the proper parameters set. I could do it myself, but I'd have to spend $500 for the software and cables to hook up my own Laptop...crazy!
 
#5 ·
redfury said:
Yup, that's the problem with these electronically controlled drivetrains...the average guy can't just dive into them and figure out what the problem is without a proper scanner. I was just quoted $275 to have my van thrown on the computer and have the PCM and transmission gone over to have the proper parameters set. I could do it myself, but I'd have to spend $500 for the software and cables to hook up my own Laptop...crazy!
As soon as I have a little extra cash, I'm buying an UltraGauge, mentioned in another thread here. See http://www.ultra-gauge.com/ultragauge/index.htm

I wanted a tach, but this not only has a digital tach, but a full scanner, including the ability to reset codes. And only $60!
 
#7 ·
UPDATE! Since this post I've replaced the encoder motor twice. It originally lasted about 2 months, The next one made it about 3 months. Oreillys wont warranty the part anymore so I have been driving with the SERVICE AWD light on for a while now. Now that its almost December I crawled under my van to test the encoder motor and it of course is shot. I guess I will try an OEM part this time, it's really all I can do at this point.
 
#8 ·
Any idea what brand the Encoder Motor from O'Reilly's was? There are numerous brands of aftermarket and rebuilt units available through Rock Auto, Auto Zone, Advance etc. with a full range of prices as well. Just curious which brand you had the quality issue with. Thanks.
 
#9 ·
Disregard my last question. Looked at O'Reilly's website and for the price you quoted the motor was a Cardone which is a rebuilt motor. Just saw your other post where you thought it was a Dorman. The Dormans are over $ 200.00 but are new, not rebuilt.

I'm having a Dorman put on mine today, so will update if there are any issues or problems with that one as well. Keeping my fingers crossed. I've bought other Dorman products and had no issues, so hoping that hold true for the encoder motor as well.
 
#11 ·
I refurbished my transfer case motor and thought someone might like seeing what's inside. Yes, I have more time than money at the moment.

I'm not sure this is a worthwhile project but I was reluctant to buy a new motor based on the bad experience rubrbulits had with them. Worst case scenario the refurb would not work and I only lose a little time. The brushes and commutator looked like they had enough material left to last long enough to make a refurb worthwhile.

I don't like the design of this part. I think it could have been made so the motor could be replaced as a separate part rather than replacing the whole assembly. The planetary gearbox and the gears in the flat housing probably account for 90% of the cost of a new unit and they look like they would last forever. The electric motor itself is nothing more than you would see in a cheap toy and could be sold at low cost. As designed, you have to take everything apart to remove the motor. Dumb.

I had the typical symptoms discussed earlier and measured high resistance across the motor terminals. Light came on about 75% of the time when starting the van. Once I got it apart there was a lot of carbon floating around and the commutator was solid black instead of copper color. I cleaned them up with small needle files and contact cleaner then blew everything out with compressed air. Resistance after was .5 Ohm.

The hardest part of the project was putting the brushes and springs back in the motor. The front part of the motor holding the brushes can only be separated by about .5" so you are working through a small gap. The brushed are held against the commutator by some little springs. You need the dexterity of a three handed brain surgeon get them coiled up and back into place while keeping the brushes in position. Now that I have a technique figured out I could probably do it in 1/4 the time.

The planetary gearbox is held onto the front of the motor with three spiral tension pins. I drilled them out but in hindsight I maybe could have pressed them out and reused them. I ended up drilling and taping the holes and using screws to reattach the planetary housing to the motor.

So far my service AWD light is staying out since putting it back in. Time will tell if works long term.
 
#16 ·
Looking on rockauto.com I see two motors. One is listed as a 4wd actuator (listed under drivetrain) and has a yellow arm in the flat sided hole and the other is listed under " transfer case" (motor) and looks identical but without the yellow lever. $117 vs $301.

I just bought a '02 AWD with no light on dash and old owner reported won't go into AWD. They had computer swapped and still nothing. 82k miles. Now I am reading on what to look for.

Ron
 
#17 ·
Alaskastreamin said:
I just bought a '02 AWD with no light on dash and old owner reported won't go into AWD. They had computer swapped and still nothing. 82k miles. Now I am reading on what to look for.

Ron
Since this post was about a service AWD light being stuck on because of a bad motor, I would start or look for another post about no service AWD light. There is going to be a different cause for this problem.
 
#18 ·
Thread resurrection!

Long time lurker here; I appreciate the time you all have put into this excellent resource.

Does anyone have re-installation torque specs for the servo motor and front drive shaft bolts? Neither the Chilton or Hayes has the AWD parts, so not sure if they take a good 'uhmpf' or if they need a certain torque for proper function.

Thanks all!
 
#20 ·
Nice necro! I've been thinking of a similar mod. It would be nice to nix the motor but even a manual switch that controlled the motor would be better than the stock setup.

Jp400motox said:
I am thinking of trashing the motor off the unit and fabing a manual lever in its place with a cable or rod going into the cabbin. Like a parking brake hand lever... thoughts?
 
#21 ·
You guys are great! I'm not mechanically inclined, but I was able to find, RIGHT ON THIS FORUM, discussions about the clicking symptoms when turning key "on" in ignition, (1999 GMC Safari, AWD, just purchased a few weeks ago), along with "Service AWD" light going on, (on lower left of dashboard)---and those symptoms thanks to you guys, was apparently pointing towards my Safari having a bad "encoder motor" (of Transfer Case).

I was going to FIRST have the transfer case Auto Track II fluid changed, but a little voice in my head (thanks to you all!) said--ask my local mechanic to run his code machine on my minivan, BEFORE getting the new fluid put in:

So, this morning, I asked my local mechanic in Granby, CO (Mike) to check codes, and "voila!", his excellent code machine said:

C0310, Motor A/B Circuit Open!!! That was what others here have already kindly shared, about resistance problems (goes over my head, regarding exact particulars) between A & B on the transfer case "encoder motor"!!!

Mike ordered a NAPA re-manufactured (NOT Dorman!!) Transfer Case ENCODER MOTOR, and he will put it in, along with brand new transfer case fluid, tomorrow morning! He thinks the clicking sound, when key is turned on, in ignition, might be coming from the TCCM (Transfer Case Control Module), located low down on the left, near the interior fuse box.

I just want to thank you all, again, for your great and generous comments here! I too, will let you know how long the "new" Transfer Case ENCODER MOTOR lasts!
 
#22 ·
Carol said:
He thinks the clicking sound, when key is turned on, in ignition, might be coming from the TCCM (Transfer Case Control Module), located low down on the left, near the interior fuse box.
That clicking is the tell tale sign of a bad encoder motor. There are cheap bluetooth scanners that you can get for $20something from Amazon(even cheaper if you want to get it shipped from overseas) that will read those codes for you on your phone/tablet. I use Scan Gauge Pro ($4) from play.google.com on my Android tablet/phone, it has the extended codes as well as all the standard stuff.

JuneauCabbie said:
As soon as I have a little extra cash, I'm buying an UltraGauge, mentioned in another thread here. See http://www.ultra-gauge.com/ultragauge/index.htm

I wanted a tach, but this not only has a digital tach, but a full scanner, including the ability to reset codes. And only $60!
The wired one is a decent deal, but screw them on their bluetooth version they are freaking insane, $80 my ***. If you shop around you can get a bluetooth adapter for under $20 and then choose your own software.
 
#23 ·
I realize this is an old post. But just in case (no pun intended)

I have also been getting a Service AWD light on. Two questions:

1. Is it a encoder motor replacement a difficult repair to do?

2. At a local Oil and Lube place, I was told the differential and transfer case fluid are the same. Does not sound right? Please confirm.

Thanks.
 
#24 ·
romeroom said:
I realize this is an old post. But just in case (no pun intended)

I have also been getting a Service AWD light on. Two questions:

1. Is it a encoder motor replacement a difficult repair to do?

2. At a local Oil and Lube place, I was told the differential and transfer case fluid are the same. Does not sound right? Please confirm.

Thanks.
Yes it's fairly easy to do. You have to unbolt the front prop shaft to get at the 3 bolts.

10mm and 15mm iirc.

The transfer case takes autotracII, not gear oil, or atf.

Rear diff in my 2003 takes 75/90 synthetic and the front diff is standard 80/90 gear oil.
 
#25 ·
romeroom said:
I have also been getting a Service AWD light on.
Just having an AWD light on does not mean that the encoder motor is bad, even though their failure is quite common, you should always check the codes and do a diagnosis.

romeroom said:
2. At a local Oil and Lube place, I was told the differential and transfer case fluid are the same. Does not sound right? Please confirm.
This is why you should do your own work. This kind of information is in the user manual viewforum.php?f=110

Here is an example of one of mine:
example.png
 
#26 ·
Thanks to all of you who have responded.

The "Service AWD" light is on now all of the time. I have a cheap OBDII scanner and it says nothing about the Service AWD light. I also get the clicking in lower left near the driver's feet upon key ignition.

1. What else do I need to do to confirm it is a bad encoder motor? I don't really feel like taking it to the dealer to have them charge me $50 - $100 to connect a specialty scanner and read the code.

2. Major stupid question: If I end up replacing the encoder motor, do I need to remove the old transf fluid?
 
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