may be having trouble with awd

FROM AWD'S TO 2-SPEED MANUAL SHIFT, IF IT LINKS THE REAR AXLE TO THE FRONT AXLE, POST IT HERE.

Moderator: Cobra

Post Reply
astrojohn
I am smitten with my van
Posts: 38
Joined: Sat Oct 08, 2011 10:57 pm
antispam: No
How many wheels are on an Astro van? (4): 4

may be having trouble with awd

Post by astrojohn » Sun Jan 20, 2013 1:13 am

Does anyone have the schematic for the AWD system in a 2000 Astro van?
What sensors or...... tell the encoder motor to engage the front wheels when it is needed.
I want to do some troubleshooting on it, as I don't think it is working properly. I want to check out the electrical part of the system, before tackling the encoder motor.
My 95 Safari, had full time awd, and I have never gotten stuck with it, and I've pushed through some pretty deep snow drifts.
The rear tires seem to spin way too much on ice patches with the 2000, and I've noticed that places I went with the 95, I'm not sure I want to go with the 2000, because the traction does not seem to be there.
I'd appreciate anyone with some good advice, and answers to my questions.
Thanks to all who answer.

User avatar
timelessbeing
Site Admin
Site Admin
Posts: 2715
Joined: Fri Aug 08, 2008 7:55 pm
antispam: No
How many wheels are on an Astro van? (4): 4

Re: may be having trouble with awd

Post by timelessbeing » Sun Jan 20, 2013 3:05 am

The transfer case control module (near your left foot) monitors the front and rear driveshaft speed sensors (on the transfer case itself). Based on the difference in speed, the module drives the encoder motor with a PWM signal, varying between 0 to 95% duty cycle.

To check:
* ATC fuse
* sensors (unlikely) - they should produce faint (mV) pulses as the shaft turns. Measure with a DMM.
* encoder motor (likely) - apply 12V.
* control module (unlikely) - put a 12V bulb across the outputs.

If everything is OK electrically (obviously checking for continuity along all wires as well), the clutches are probably pooched.

Hope that helps. If you would still like the diagram, PM me your email address.

LiftedAWDAstro
Site Admin
Site Admin
Posts: 4430
Joined: Sat Sep 09, 2006 10:35 pm
How many wheels are on an Astro van? (4): 6
Location: New Haven, NY

Re: may be having trouble with awd

Post by LiftedAWDAstro » Sun Jan 20, 2013 3:23 am

If the fuse is ok, you have about a 99% chance it's the encoder motor or the clutches themselves. If it's the clutches, you will feel the front engage but it will be delayed by what seems like a second or 2. If it doesn't seem to engage at all it is most likely the encoder motor.
Current rides:
2013 Toyota Tundra DC 4x4
2008 Dodge Nitro 4x4
2005 Nissan Sentra 1.8S Special Edition

Mileage spreadsheet

Vans owned:
1986 Safari 2.5L 4 speed manual - scrapped
1995 Astro 2WD conversion 4.11 posi, shift kit, DHC rock rails - sold to Skippy
1998 Astro 4x4 D44, D60, NP231, full hydraulic system with 9k# Milemarker winch and snow plow - sold to Lockdoc
2003 Astro AWD all stock - traded for a 3/4 ton truck
2005 AWD, 4.10's - sold to skippy

User avatar
timelessbeing
Site Admin
Site Admin
Posts: 2715
Joined: Fri Aug 08, 2008 7:55 pm
antispam: No
How many wheels are on an Astro van? (4): 4

Re: may be having trouble with awd

Post by timelessbeing » Wed Jan 23, 2013 4:53 am

Thank you for your PM, John. If you don't mind, I'll reply here so the information can help others as well.
astrojohn wrote:When I bought this van, it was being sold because the rear end was out, and was being sold for scrap price. I couldn't let it go, so I bought it. I installed a different rearend ( spiders were out on the original)
Did the rear end you put in have the exact same gear ratio as the original one? Are all your tire diamaters exactly the same, within 1/4"? (don't just trust the numbers printed on the sidewall) Consistent tire pressure? If not, the TCCM will incorrectly sense that you are slipping and engage the AWD system, leading to damage.
astrojohn wrote:When I first started driving it, the AWD light would come on, and stay on. But if I shut it off, and re started it, the light would go off. I could always tell if it would stay on, because something would buzz about 5 times, down near my left foot. Must have been the module you are talking about.
This happened to me for the first couple weeks I drove it. Now it doesn't come on at all.
The buzzing doesn't sound normal. Did you test the encoder motor? Does the "Service AWD" light come on during the gauge cluster check at startup? Getting that code scanned could help immensely with your troubleshooting, and save you time and money.
astrojohn wrote:where I store my snowmobiles, I could back down the hill with a trailer, load up the sleds, and drive right back up the icy hill, and not spin.
I did it with this van, sans the trailer and sleds, and left a one wheel spin mark up the hill. Then the AWD light came on, but there were no indications of a front wheel spinning, or pulling...Does the AWD work in reverse, on these vans?
Yes, the AWD works in reverse, and any time front and rear wheel speeds differ.
Attachments
TC.gif

astrojohn
I am smitten with my van
Posts: 38
Joined: Sat Oct 08, 2011 10:57 pm
antispam: No
How many wheels are on an Astro van? (4): 4

Re: may be having trouble with awd

Post by astrojohn » Wed Jan 23, 2013 11:25 pm

The van has the GU6 code rearend, which is a 3:42. The donor van, was another astro van, but didn't have awd. I did check the rearend code on the passenger door, to be sure.
The tires are all brand new, and the same size, so I'm sure that is OK.
The buzzing, which seemed like it was coming from behind the dash on the driver side would only buzz or whatever noise it made, 5 times, then the service awd light would come on, and stay on. If I shut the van off and re started, if there wasn't 5 buzzes, the light would only come on during the dash light check, and then go out.
Never once, have I ever felt it engage, or feel like it has. The tires must be doing a teriffic job keeping me on the road, because I do not feel afraid of losing control on a snowy or icy road.
As I stated, the light only comes on now, when I first start up, when all the other lights come on, then goes out.
This morning was the first time I noticed any slip, after taking off from a stop light, I almost went sideways. Never had that happen in any of my other Astro/Safari's.
It probably is the encoder motor, and will have to change it. Will I lose any of the blue fluid out of the transfer case when I do it?
Just want to know so I have some on hand.
Thanks for the download pic, showing where the speed sensors are etc.
Would still like to have that copy of the AWD wiring schematic though, so I can add it to the rest of the ones I have. You do have my e-mail address.
It may not be a big thing, but it's nice to know that the awd works all the time, even in reverse. I've read through countless articles on awd, and never once read what you told me. Amazing! Now I know why it is so surefooted.
I do have the basic obdII scanner tool, but it doesn't read awd or aws, so will have to have it done somewhere else.
Thank you so much for the knowledge you shared with me, and anyone else who reads this.

User avatar
timelessbeing
Site Admin
Site Admin
Posts: 2715
Joined: Fri Aug 08, 2008 7:55 pm
antispam: No
How many wheels are on an Astro van? (4): 4

Re: may be having trouble with awd

Post by timelessbeing » Wed Jan 23, 2013 11:57 pm

Ideally, the AWD activation should be completely seamless and transparent to the driver. The TC should fully engage in about 75 milliseconds, therefore you should not feel it. However, if either of your rear wheels are slipping, you should see at least one front wheel turn.

I'm not sure if fluid will come out of the encoder motor hole or not. If it does, you could always drain it out first and then put it back in after. But you don't need to remove the motor to test it. Just unplug the connector, and give it 12V with some aligator clips or something. Try both polarities since it operates in both directions anyway.

User Drummernaut made an indicator light that illuminates when the TCCM sends power to the encoder motor. (he has even posted the schematic you're looking for) Something like that could help you see if the TCCM is working properly, but you don't even need anything that fancy. A plain 12v automotive bulbs with a couple long wire leads will accomplish the same thing for you. viewtopic.php?f=58&t=8948

Good luck and keep us posted on your progress. :cheers:

astrojohn
I am smitten with my van
Posts: 38
Joined: Sat Oct 08, 2011 10:57 pm
antispam: No
How many wheels are on an Astro van? (4): 4

Re: may be having trouble with awd

Post by astrojohn » Sun Feb 10, 2013 8:04 pm

The weather hasn't been cooperating around here lately, and I haven't gone underneith the van to check for faulty or corroded connections.
Twice now, I've had someone watch the front wheels, as I stepped on the gas, while on ice. The first time, the awd kicked in, and the front wheel spun. the next two times I tried it, neither front wheel spun. Trying again last night, on ice, the front end did not kick in.
The funny thing is, that other than a couple times turning a street corner, the van has felt as surefooted as a mountain goat. I am not afraid to drive it in any kind of weather.
Anyone have these symptoms, and have an answer to what fixed their problem?

LiftedAWDAstro
Site Admin
Site Admin
Posts: 4430
Joined: Sat Sep 09, 2006 10:35 pm
How many wheels are on an Astro van? (4): 6
Location: New Haven, NY

Re: may be having trouble with awd

Post by LiftedAWDAstro » Sun Feb 10, 2013 8:21 pm

Might be time for a shift motor. Usually a bad shift motor throws a code so maybe the clutches are worn enough you need to rebuild the t-case or install a used one.
Current rides:
2013 Toyota Tundra DC 4x4
2008 Dodge Nitro 4x4
2005 Nissan Sentra 1.8S Special Edition

Mileage spreadsheet

Vans owned:
1986 Safari 2.5L 4 speed manual - scrapped
1995 Astro 2WD conversion 4.11 posi, shift kit, DHC rock rails - sold to Skippy
1998 Astro 4x4 D44, D60, NP231, full hydraulic system with 9k# Milemarker winch and snow plow - sold to Lockdoc
2003 Astro AWD all stock - traded for a 3/4 ton truck
2005 AWD, 4.10's - sold to skippy

User avatar
timelessbeing
Site Admin
Site Admin
Posts: 2715
Joined: Fri Aug 08, 2008 7:55 pm
antispam: No
How many wheels are on an Astro van? (4): 4

Re: may be having trouble with awd

Post by timelessbeing » Sun Feb 10, 2013 9:44 pm

Maybe it's time to get your hands dirty. :poke:

Post Reply